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RE: [Cadillac_Performance_Association] Re: The '49-'62 V8... anything out there?

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  • Jerry Brown
    You have to be an old guy to remember crankcase breathers. All the cars had them until the smog nazis took control. Actually no one knew any better than to let
    Message 1 of 25 , Dec 8, 2004
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      You have to be an old guy to remember crankcase breathers. All the cars had
      them until the smog nazis took control. Actually no one knew any better than
      to let the vapors out. It relieved pressure in the crankcase from blowby on
      the cylinders. Now of course that is all handled and recycled back through
      the intake again and then out the exhaust. no doubt better now for our
      lungs. It used to be a really easy way to check engine condition to just put
      your hand over the breather tube with the engine at idle and if you felt the
      pressure you knew there was too much blow by. Rocker arm covers were also
      vented directly to the air back then.
      Jerry Brown (an old guy)

      PS...I'm looking at a 76 Cad 500 engine for my 36 Chev coupe. Engine tests
      out at 123-128 psi on all cyl. so I'm thinking its pretty good. Seller wants
      $375. I'm new to the cad engine market so don't know if this is a good buy
      or not. Any advice?

      -----Original Message-----
      From: dave [mailto:inanno@...]
      Sent: Wednesday, December 08, 2004 5:11 PM
      To: Cadillac_Performance_Association@yahoogroups.com
      Subject: Re: [Cadillac_Performance_Association] Re: The '49-'62 V8...
      anything out there?



      It's a long tube, about 1" diameter that runs from the
      back of the valley cover and down towards the ground.
      i believe it serves as a crankcase vent. i don't know
      if they had them on all years, but i had them on both
      my '62s, and a spare '59 motor i got.

      ..dave


      --- Cirilian <cirilian@...> wrote:

      >
      > You'll forgive my ignorance but what exactly is the
      > road draft tube?
      > I was considering one of these finned valey covers
      > for my "60.
      > Thanks,
      > Richard
      >


      =====
      '63-'64 Chrysler fans- we have a home! Check out
      http://groups.yahoo.com/group/63-64Chryslers
      - -
      "If elected mayor, my first act will be to kill the whole lot of you, and
      burn your town to cinders!"



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    • Pollorey
      Doesn t sound like a bad price. ... From: Jerry Brown [mailto:jerome@pacifier.com] Sent: Wednesday, December 08, 2004 11:01 PM To:
      Message 2 of 25 , Dec 9, 2004
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        Doesn't sound like a bad price.

        -----Original Message-----
        From: Jerry Brown [mailto:jerome@...]
        Sent: Wednesday, December 08, 2004 11:01 PM
        To: Cadillac_Performance_Association@yahoogroups.com
        Subject: RE: [Cadillac_Performance_Association] Re: The '49-'62 V8...
        anything out there?


        You have to be an old guy to remember crankcase breathers. All the cars had
        them until the smog nazis took control. Actually no one knew any better than
        to let the vapors out. It relieved pressure in the crankcase from blowby on
        the cylinders. Now of course that is all handled and recycled back through
        the intake again and then out the exhaust. no doubt better now for our
        lungs. It used to be a really easy way to check engine condition to just put
        your hand over the breather tube with the engine at idle and if you felt the
        pressure you knew there was too much blow by. Rocker arm covers were also
        vented directly to the air back then.
        Jerry Brown (an old guy)

        PS...I'm looking at a 76 Cad 500 engine for my 36 Chev coupe. Engine tests
        out at 123-128 psi on all cyl. so I'm thinking its pretty good. Seller wants
        $375. I'm new to the cad engine market so don't know if this is a good buy
        or not. Any advice?

        -----Original Message-----
        From: dave [mailto:inanno@...]
        Sent: Wednesday, December 08, 2004 5:11 PM
        To: Cadillac_Performance_Association@yahoogroups.com
        Subject: Re: [Cadillac_Performance_Association] Re: The '49-'62 V8...
        anything out there?



        It's a long tube, about 1" diameter that runs from the
        back of the valley cover and down towards the ground.
        i believe it serves as a crankcase vent. i don't know
        if they had them on all years, but i had them on both
        my '62s, and a spare '59 motor i got.

        ..dave


        --- Cirilian <cirilian@...> wrote:

        >
        > You'll forgive my ignorance but what exactly is the
        > road draft tube?
        > I was considering one of these finned valey covers
        > for my "60.
        > Thanks,
        > Richard
        >


        =====
        '63-'64 Chrysler fans- we have a home! Check out
        http://groups.yahoo.com/group/63-64Chryslers
        - -
        "If elected mayor, my first act will be to kill the whole lot of you, and
        burn your town to cinders!"



        __________________________________
        Do you Yahoo!?
        The all-new My Yahoo! - Get yours free!
        http://my.yahoo.com






        Yahoo! Groups Links













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      • Scott Pearson
        I m not an old guy and I know what a road vent tube is. That s not a bad price for a decent, even rebuildable, Caddy motor. It seems that alot of it depends on
        Message 3 of 25 , Dec 9, 2004
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          I'm not an old guy and I know what a road vent tube is.

          That's not a bad price for a decent, even rebuildable, Caddy motor. It seems
          that alot of it depends on where you live. In my area there's not much
          demand, so prices are quite low. I've bought several for $100 or even 'you
          take it out, it's yours'

          Scott

          ----- Original Message -----
          From: "Jerry Brown" <jerome@...>
          To: <Cadillac_Performance_Association@yahoogroups.com>
          Sent: Wednesday, December 08, 2004 10:00 PM
          Subject: RE: [Cadillac_Performance_Association] Re: The '49-'62 V8...
          anything out there?


          >
          > You have to be an old guy to remember crankcase breathers. All the cars
          > had
          > them until the smog nazis took control. Actually no one knew any better
          > than
          > to let the vapors out. It relieved pressure in the crankcase from blowby
          > on
          > the cylinders. Now of course that is all handled and recycled back through
          > the intake again and then out the exhaust. no doubt better now for our
          > lungs. It used to be a really easy way to check engine condition to just
          > put
          > your hand over the breather tube with the engine at idle and if you felt
          > the
          > pressure you knew there was too much blow by. Rocker arm covers were also
          > vented directly to the air back then.
          > Jerry Brown (an old guy)
          >
          > PS...I'm looking at a 76 Cad 500 engine for my 36 Chev coupe. Engine tests
          > out at 123-128 psi on all cyl. so I'm thinking its pretty good. Seller
          > wants
          > $375. I'm new to the cad engine market so don't know if this is a good buy
          > or not. Any advice?
          >
          > -----Original Message-----
          > From: dave [mailto:inanno@...]
          > Sent: Wednesday, December 08, 2004 5:11 PM
          > To: Cadillac_Performance_Association@yahoogroups.com
          > Subject: Re: [Cadillac_Performance_Association] Re: The '49-'62 V8...
          > anything out there?
          >
          >
          >
          > It's a long tube, about 1" diameter that runs from the
          > back of the valley cover and down towards the ground.
          > i believe it serves as a crankcase vent. i don't know
          > if they had them on all years, but i had them on both
          > my '62s, and a spare '59 motor i got.
          >
          > ..dave
          >
          >
          > --- Cirilian <cirilian@...> wrote:
          >
          >>
          >> You'll forgive my ignorance but what exactly is the
          >> road draft tube?
          >> I was considering one of these finned valey covers
          >> for my "60.
          >> Thanks,
          >> Richard
          >>
          >
          >
          > =====
          > '63-'64 Chrysler fans- we have a home! Check out
          > http://groups.yahoo.com/group/63-64Chryslers
          > - -
          > "If elected mayor, my first act will be to kill the whole lot of you, and
          > burn your town to cinders!"
          >
          >
          >
          > __________________________________
          > Do you Yahoo!?
          > The all-new My Yahoo! - Get yours free!
          > http://my.yahoo.com
          >
          >
          >
          >
          >
          >
          > Yahoo! Groups Links
          >
          >
          >
          >
          >
          >
          >
          >
          >
          >
          >
          >
          >
          > Yahoo! Groups Links
          >
          >
          >
          >
          >
          >
          >
          >
        • jvandecreek25
          ... Engine tests ... Seller wants ... good buy ... That s not a bad price if it is complete, if you have to spend extra to replace missing accessories, like
          Message 4 of 25 , Dec 9, 2004
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            > Jerry Brown (an old guy)
            >
            > PS...I'm looking at a 76 Cad 500 engine for my 36 Chev coupe.
            Engine tests
            > out at 123-128 psi on all cyl. so I'm thinking its pretty good.
            Seller wants
            > $375. I'm new to the cad engine market so don't know if this is a
            good buy
            > or not. Any advice?

            That's not a bad price if it is complete, if you have to spend
            extra to replace missing accessories, like manifolds, brackets and
            pulleys, the price could easily double, so try to find as complete a
            package as you can, Does it include the trans? most DeVills (RWD)
            will come with the trans, but Eldos usually don't.
          • Jerry Brown
            PS...I m looking at a 76 Cad 500 engine for my 36 Chev coupe. Engine tests ... Seller wants ... good buy ... That s not a bad price if it is complete, if you
            Message 5 of 25 , Dec 9, 2004
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              PS...I'm looking at a 76 Cad 500 engine for my 36 Chev coupe.
              Engine tests
              > out at 123-128 psi on all cyl. so I'm thinking its pretty good.
              Seller wants
              > $375. I'm new to the cad engine market so don't know if this is a
              good buy
              > or not. Any advice?

              That's not a bad price if it is complete, if you have to spend
              extra to replace missing accessories, like manifolds, brackets and
              pulleys, the price could easily double, so try to find as complete a
              package as you can, Does it include the trans? most DeVills (RWD)
              will come with the trans, but Eldos usually don't.


              Its complete right down to A/C compressor, alternator, belts, carb,
              manifolds and some wiring. No transmission but that is no problem as I have
              a recently rebuilt TH400 from a 74 472 engine that is a basket case. I
              assume the bell housing is the same whether DeVille or Eldorado. Am I
              correct?

              I looked up the HP and Torque for this engine and have to say its less than
              impressive for the displacement. I can see why so many go to higher
              compression, performance cam, headers and different intake.

              Nother question: Is it acceptable practice to mill the heads to raise
              compression a point to a point-and-a-half? If so do you have to go to
              different length pushrods or will there still be sufficient clearance
              between valves and piston? I'm looking for about 9.5:1 CR to help out
              performance. I know the best way to go is usually different pistons but I'm
              trying to keep the costs reasonable.

              Thanks. You guys have been great with the information and advice.

              Jerry Brown
            • jvandecreek25
              ... a ... as I have ... case. I ... Am I ... less than ... raise ... to ... clearance ... out ... pistons but I m ... Don t worry too much about the seemingly
              Message 6 of 25 , Dec 9, 2004
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                --- In Cadillac_Performance_Association@yahoogroups.com, "Jerry
                Brown" <jerome@p...> wrote:
                > PS...I'm looking at a 76 Cad 500 engine for my 36 Chev coupe.
                > Engine tests
                > > out at 123-128 psi on all cyl. so I'm thinking its pretty good.
                > Seller wants
                > > $375. I'm new to the cad engine market so don't know if this is a
                > good buy
                > > or not. Any advice?
                >
                > That's not a bad price if it is complete, if you have to spend
                > extra to replace missing accessories, like manifolds, brackets and
                > pulleys, the price could easily double, so try to find as complete
                a
                > package as you can, Does it include the trans? most DeVills (RWD)
                > will come with the trans, but Eldos usually don't.
                >
                >
                > Its complete right down to A/C compressor, alternator, belts, carb,
                > manifolds and some wiring. No transmission but that is no problem
                as I have
                > a recently rebuilt TH400 from a 74 472 engine that is a basket
                case. I
                > assume the bell housing is the same whether DeVille or Eldorado.
                Am I
                > correct?
                >
                > I looked up the HP and Torque for this engine and have to say its
                less than
                > impressive for the displacement. I can see why so many go to higher
                > compression, performance cam, headers and different intake.
                >
                > Nother question: Is it acceptable practice to mill the heads to
                raise
                > compression a point to a point-and-a-half? If so do you have to go
                to
                > different length pushrods or will there still be sufficient
                clearance
                > between valves and piston? I'm looking for about 9.5:1 CR to help
                out
                > performance. I know the best way to go is usually different
                pistons but I'm
                > trying to keep the costs reasonable.
                >
                > Thanks. You guys have been great with the information and advice.
                >
                > Jerry Brown
                Don't worry too much about the seemingly low hp. ratings, in actual
                performance in a light vehicle there is not of much noticable
                difference, you could mill the heads but a better choice is to swap
                on a set of 425 heads, compression will be about 10:5 and will give
                you and easy 40 hp more, not the best breathing for all out racing,
                but fine up to around 4500 rpm, making for strong street performance
                cheap, next best change is a good cam, then an Edelbrock intake.
                Your 472 Trans will bolt right up.
              • Jerry Brown
                Thanks for the additional information re. 425 heads on 500 engine. Are the differences in the combustion chamber so that I don t need to change out valve train
                Message 7 of 25 , Dec 9, 2004
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                  Thanks for the additional information re. 425 heads on 500 engine. Are the
                  differences in the combustion chamber so that I don't need to change out
                  valve train etc.?

                  Don't worry too much about the seemingly low hp. ratings, in actual
                  performance in a light vehicle there is not of much noticable
                  difference, you could mill the heads but a better choice is to swap
                  on a set of 425 heads, compression will be about 10:5 and will give
                  you and easy 40 hp more, not the best breathing for all out racing,
                  but fine up to around 4500 rpm, making for strong street performance
                  cheap,
                • jvandecreek25
                  ... Are the ... change out ... The late 500 heads have 120cc chambers, while the 425 heads have 96cc chambers, this is where the increase in compression comes
                  Message 8 of 25 , Dec 9, 2004
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                    --- In Cadillac_Performance_Association@yahoogroups.com, "Jerry
                    Brown" <jerome@p...> wrote:
                    > Thanks for the additional information re. 425 heads on 500 engine.
                    Are the
                    > differences in the combustion chamber so that I don't need to
                    change out
                    > valve train etc.?

                    The late 500 heads have 120cc chambers, while the 425 heads have
                    96cc chambers, this is where the increase in compression comes from.
                    The 425 head has the same valve sizes, and the same intake and
                    exhaust ports as the late 500 head, the factory did remove some
                    weight by opening up the area where the push-rods pass through, but
                    this change has no effect on performance or durability.
                    Earlier '69-'73 heads do have better, more direct exhaust ports and
                    work better on a race type engine, but the compression goes to over
                    12:1 when used with the flat top pistons of a '74-'76 500(and 472)
                    and these stock cast pistons are prone to disintegrating at those
                    compression ratios, this combination is not at all streetable on
                    available pump gas.
                    So for "Bang for the buck",
                    Install the 425 heads, use a 425 head gasket(can be an old used
                    one) to locate the positions of the extra steam holes that will need
                    to be drilled in the block deck of the 500, a 3/8" electric drill
                    with the appropriate size bit is all that will be required, assemble
                    the heads to the block using 500 head gaskets. no other
                    modifications or non stock parts are needed.
                  • david brode
                    Jerry, The 74- 76 500s have 120+ cc chambers and a very small dish. If the bores look good, you could just deck the block for a .040 or so assembled quench,
                    Message 9 of 25 , Dec 11, 2004
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                      Jerry,

                      The '74-'76 500s have 120+ cc chambers and a very small dish. If the
                      bores look good, you could just deck the block for a .040" or so
                      assembled quench, and whack the heads to get to *maybe* 9.5-1. Fyi -
                      KB makes no dish flat tops for it if it needs bored [which I doubt it
                      will].

                      Another option would be dished KB designed for the early heads. They
                      give 10-2-1 or so with the '68-'73 heads [76cc]. Another option is to
                      use 107cc 425 heads on your shortblock. They'll put you a little over
                      9.5-1. The 425 heads don't flow as well as yours, but a little work
                      and they'll do ok. The 76cc heads flow better than yours, btw, but
                      not much in stock form. More fyi - 2.11"/1.66&1.77" pontiac valves
                      fit the 107 and 120cc heads perfectly. For larger valves on the 76cc,
                      aftermarket valves are available from the caddy
                      parts vendors.
                      Dave




                      > Nother question: Is it acceptable practice to mill the heads to
                      raise
                      > compression a point to a point-and-a-half? If so do you have to go
                      to
                      > different length pushrods or will there still be sufficient
                      clearance
                      > between valves and piston? I'm looking for about 9.5:1 CR to help
                      out
                      > performance. I know the best way to go is usually different pistons
                      but I'm
                      > trying to keep the costs reasonable.
                      >
                      > Thanks. You guys have been great with the information and advice.
                      >
                      > Jerry Brown
                    • david brode
                      jvandecreek25, The 425 heads will not gain near that much in compression. It has been said that they are 96cc, but I believe they are more like 107cc or so.
                      Message 10 of 25 , Dec 11, 2004
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                        jvandecreek25,

                        The 425 heads will not gain near that much in compression. It has
                        been said that they are 96cc, but I believe they are more like 107cc
                        or so. That figure comes from experts that I trust.

                        CR on a stock engine can vary. Assuming a stock late 500 is 8-1, and
                        the heads are 120cc, the 13cc reduction in combustion space would
                        raise the CR to 8.7-1. Assuming the stock engine was 8.5-1, the
                        change would give 9.25-1.

                        It would take a change in combustion space of apx 27.5cc to raise
                        compression of an 8.5-1 engine to 10.5-1.
                        Dave




                        much about the seemingly low hp. ratings, in actual
                        > performance in a light vehicle there is not of much noticable
                        > difference, you could mill the heads but a better choice is to swap
                        > on a set of 425 heads, compression will be about 10:5 and will give
                        > you and easy 40 hp more, not the best breathing for all out racing,
                        > but fine up to around 4500 rpm, making for strong street
                        performance
                        > cheap, next best change is a good cam, then an Edelbrock intake.
                        > Your 472 Trans will bolt right up.
                      • jvandecreek25
                        ... 107cc ... and ... After I posted I realised I had over-shot on the amount of compression increase, the figure I gave was one I had seen posted
                        Message 11 of 25 , Dec 12, 2004
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                          --- In Cadillac_Performance_Association@yahoogroups.com, "david
                          brode" <dbrode@h...> wrote:
                          >
                          > jvandecreek25,
                          >
                          > The 425 heads will not gain near that much in compression. It has
                          > been said that they are 96cc, but I believe they are more like
                          107cc
                          > or so. That figure comes from experts that I trust.
                          >
                          > CR on a stock engine can vary. Assuming a stock late 500 is 8-1,
                          and
                          > the heads are 120cc, the 13cc reduction in combustion space would
                          > raise the CR to 8.7-1. Assuming the stock engine was 8.5-1, the
                          > change would give 9.25-1.
                          >
                          > It would take a change in combustion space of apx 27.5cc to raise
                          > compression of an 8.5-1 engine to 10.5-1.
                          > Dave

                          After I posted I realised I had over-shot on the amount of
                          compression increase, the figure I gave was one I had seen posted
                          elsewhere,and I never took time to confirm it.
                          However the figure for the 40 hp increase did come directly from Al
                          Betker of MTS,one of the most experienced Cadillac builders to be
                          found.
                          If this 40 hp improvement comes from an increase to only 9.25-1,
                          then so much the better.
                        • jvandecreek25
                          ... the ... Fyi - ... it ... They ... to ... over ... work ... 76cc, ... I m looking for about 9.5:1 CR to help out performance. I know the best way to go is
                          Message 12 of 25 , Dec 12, 2004
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                            --- In Cadillac_Performance_Association@yahoogroups.com, "david
                            brode" <dbrode@h...> wrote:
                            >
                            > Jerry,
                            >
                            > The '74-'76 500s have 120+ cc chambers and a very small dish. If
                            the
                            > bores look good, you could just deck the block for a .040" or so
                            > assembled quench, and whack the heads to get to *maybe* 9.5-1.
                            Fyi -
                            > KB makes no dish flat tops for it if it needs bored [which I doubt
                            it
                            > will].
                            >
                            > Another option would be dished KB designed for the early heads.
                            They
                            > give 10-2-1 or so with the '68-'73 heads [76cc]. Another option is
                            to
                            > use 107cc 425 heads on your shortblock. They'll put you a little
                            over
                            > 9.5-1. The 425 heads don't flow as well as yours, but a little
                            work
                            > and they'll do ok. The 76cc heads flow better than yours, btw, but
                            > not much in stock form. More fyi - 2.11"/1.66&1.77" pontiac valves
                            > fit the 107 and 120cc heads perfectly. For larger valves on the
                            76cc,
                            > aftermarket valves are available from the caddy
                            > parts vendors.
                            > Dave


                            I'm looking for about 9.5:1 CR to help out performance. I know the
                            best way to go is usually different pistons but I'm trying to keep
                            the costs reasonable.
                            Jerry Brown


                            Jerry wanted to keep the costs reasonable, to "deck the block "
                            will require a complete disassembly, and is hardly a way to keep the
                            cost down, and as he stated he did not want to get into piston
                            changes.
                            I made my recommendation based on the premise that he wanted an
                            inexpensive power increase for a engine that was going into a street
                            rod, no it is not the 'ultimate' performance build up, but if it is
                            not being used as a race car, there is no need to pursue a lot of
                            expensive modifications that are unnecessary for strong street
                            performance. Jessie
                          • Jerry Brown
                            Actually I was speculating about just milling the 500 heads to get the increased compression ratio. Since the engine would be out of the car its no big deal to
                            Message 13 of 25 , Dec 12, 2004
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                              Actually I was speculating about just milling the 500 heads to get the
                              increased compression ratio. Since the engine would be out of the car its no
                              big deal to pull the heads and have a valve job done and to mill them for
                              increased compression...So long as you don't booger up the valve train
                              ratios. It seems to me that if you mill the heads, say .040, that it would
                              drop the head lower with respect to the valve train i.e., closer to the
                              center of the camshaft, and might result in any of a number of unintended
                              results.
                              In order to keep everything in the same ratio you would have to account for
                              being .040 closer. Seems to me that pushrods that are .040 shorter should
                              compensate or taking .040 off the top of the valve stem might as long as the
                              keepers would still fit. Doesn't seem right that you wouldn't have to do
                              anything but mill to do the job right. Likewise decking the block would have
                              the same result of moving the head closer to the center of the cam. I guess
                              the right question is can milling or decking be done without unintended
                              catastrophic consequences and if so how should one compensate for the
                              changes.

                              Jerry Brown


                              -----Original Message-----
                              From: jvandecreek25 [mailto:jvandecreek@...]
                              Sent: Sunday, December 12, 2004 1:15 PM
                              To: Cadillac_Performance_Association@yahoogroups.com
                              Subject: [Cadillac_Performance_Association] Re: The '49-'62 V8...
                              anything out there?




                              --- In Cadillac_Performance_Association@yahoogroups.com, "david
                              brode" <dbrode@h...> wrote:
                              >
                              > Jerry,
                              >
                              > The '74-'76 500s have 120+ cc chambers and a very small dish. If
                              the
                              > bores look good, you could just deck the block for a .040" or so
                              > assembled quench, and whack the heads to get to *maybe* 9.5-1.
                              Fyi -
                              > KB makes no dish flat tops for it if it needs bored [which I doubt
                              it
                              > will].
                              >
                              > Another option would be dished KB designed for the early heads.
                              They
                              > give 10-2-1 or so with the '68-'73 heads [76cc]. Another option is
                              to
                              > use 107cc 425 heads on your shortblock. They'll put you a little
                              over
                              > 9.5-1. The 425 heads don't flow as well as yours, but a little
                              work
                              > and they'll do ok. The 76cc heads flow better than yours, btw, but
                              > not much in stock form. More fyi - 2.11"/1.66&1.77" pontiac valves
                              > fit the 107 and 120cc heads perfectly. For larger valves on the
                              76cc,
                              > aftermarket valves are available from the caddy
                              > parts vendors.
                              > Dave


                              I'm looking for about 9.5:1 CR to help out performance. I know the
                              best way to go is usually different pistons but I'm trying to keep
                              the costs reasonable.
                              Jerry Brown


                              Jerry wanted to keep the costs reasonable, to "deck the block "
                              will require a complete disassembly, and is hardly a way to keep the
                              cost down, and as he stated he did not want to get into piston
                              changes.
                              I made my recommendation based on the premise that he wanted an
                              inexpensive power increase for a engine that was going into a street
                              rod, no it is not the 'ultimate' performance build up, but if it is
                              not being used as a race car, there is no need to pursue a lot of
                              expensive modifications that are unnecessary for strong street
                              performance. Jessie








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                            • david brode
                              jvandecreek25, [bottom post] ... Al ... I have never CC d a pair myself. Al claims they re 96cc, iirc. Other experts claim 107cc. Dave
                              Message 14 of 25 , Dec 12, 2004
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                                jvandecreek25,

                                [bottom post]

                                <dbrode@h...> wrote:
                                > >
                                > > jvandecreek25,
                                > >
                                > > The 425 heads will not gain near that much in compression. It has
                                > > been said that they are 96cc, but I believe they are more like
                                > 107cc or so. That figure comes from experts that I trust.
                                > >
                                > > CR on a stock engine can vary. Assuming a stock late 500 is 8-1,
                                > and
                                > > the heads are 120cc, the 13cc reduction in combustion space would
                                > > raise the CR to 8.7-1. Assuming the stock engine was 8.5-1, the
                                > > change would give 9.25-1.
                                > >
                                > > It would take a change in combustion space of apx 27.5cc to raise
                                > > compression of an 8.5-1 engine to 10.5-1.
                                > > Dave
                                >
                                > After I posted I realised I had over-shot on the amount of
                                > compression increase, the figure I gave was one I had seen posted
                                > elsewhere,and I never took time to confirm it.
                                > However the figure for the 40 hp increase did come directly from
                                Al
                                > Betker of MTS,one of the most experienced Cadillac builders to be
                                > found.
                                > If this 40 hp improvement comes from an increase to only 9.25-1,
                                > then so much the better.

                                I have never CC'd a pair myself. Al claims they're 96cc, iirc. Other
                                experts claim 107cc.
                                Dave
                              • david brode
                                Jessie, [bottom]
                                Message 15 of 25 , Dec 12, 2004
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                                  Jessie,

                                  [bottom]


                                  <snip

                                  > Jerry wanted to keep the costs reasonable, to "deck the block "
                                  > will require a complete disassembly, and is hardly a way to keep
                                  the
                                  > cost down, and as he stated he did not want to get into piston
                                  > changes.
                                  > I made my recommendation based on the premise that he wanted an
                                  > inexpensive power increase for a engine that was going into a
                                  street
                                  > rod, no it is not the 'ultimate' performance build up, but if it is
                                  > not being used as a race car, there is no need to pursue a lot of
                                  > expensive modifications that are unnecessary for strong street
                                  > performance. Jessie

                                  Well, the reason I suggested decking the block for a tight quench and
                                  whacking the heads a bit, was because he said that money was an
                                  issue. Decking the block 20-30 thou costs just $65-$80 around here.
                                  Cutting the heads .050" or so would be a few more bucks, but not too
                                  much. Of course, once it's apart, hot tanmk, cam bearings, etc would
                                  cost him some. Personally, I would want to ring and bearing it
                                  anyway.

                                  The 425 head swap might be a much better bang per buck, I admit. As I
                                  see it, for a '74-'76 500, other than the 425 heads, the only other
                                  affordable option is to change to the dished KBs and 76cc heads to
                                  get any decent compression increase. Even the true flat top KBs on
                                  the 120cc heads aren't going to gain much over the very small dish
                                  stock late pistons.
                                  Dave
                                • Preston III
                                  I ve never decked the block, or shaved the heads of a Caddy engine, but if it s anything like a Chevrolet small block, there s a limit that you can go before
                                  Message 16 of 25 , Dec 12, 2004
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                                    I've never decked the block, or shaved the heads of a Caddy
                                    engine, but if it's anything like a Chevrolet small block,
                                    there's a limit that you can go before you have to do some
                                    machining to the intake manifold too. I expect that if you
                                    go past a certain extent, then you'll be in for spending
                                    even a few dollars more!

                                    Don't forget to inquire as to whether the changing geometry,
                                    and clearances of the intake/head surfaces may require a
                                    specific gasket, such as something extra thick.

                                    Also, in a true performance application, you may consider
                                    port matching the intake manifold to the intake side of
                                    the cylinder heads, as this is the dimension that will change
                                    as you go shaving things.


                                    Preston III


                                    --- david brode <dbrode@...> wrote:

                                    >
                                    > Jessie,
                                    >
                                    > [bottom]
                                    >
                                    >
                                    > <snip
                                    >
                                    > > Jerry wanted to keep the costs reasonable, to "deck the block "
                                    > > will require a complete disassembly, and is hardly a way to keep
                                    > the
                                    > > cost down, and as he stated he did not want to get into piston
                                    > > changes.
                                    > > I made my recommendation based on the premise that he wanted an
                                    > > inexpensive power increase for a engine that was going into a
                                    > street
                                    > > rod, no it is not the 'ultimate' performance build up, but if it is
                                    > > not being used as a race car, there is no need to pursue a lot of
                                    > > expensive modifications that are unnecessary for strong street
                                    > > performance. Jessie
                                    >
                                    > Well, the reason I suggested decking the block for a tight quench and
                                    > whacking the heads a bit, was because he said that money was an
                                    > issue. Decking the block 20-30 thou costs just $65-$80 around here.
                                    > Cutting the heads .050" or so would be a few more bucks, but not too
                                    > much. Of course, once it's apart, hot tanmk, cam bearings, etc would
                                    > cost him some. Personally, I would want to ring and bearing it
                                    > anyway.
                                    >
                                    > The 425 head swap might be a much better bang per buck, I admit. As I
                                    > see it, for a '74-'76 500, other than the 425 heads, the only other
                                    > affordable option is to change to the dished KBs and 76cc heads to
                                    > get any decent compression increase. Even the true flat top KBs on
                                    > the 120cc heads aren't going to gain much over the very small dish
                                    > stock late pistons.
                                    > Dave
                                    >
                                    >
                                    >
                                    >
                                    >




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                                  • david brode
                                    Jerry, I ve only seen a few late 500s apart, but they all were pretty decent as far as deck to piston. Assuming you have eom pistons and they re good shape,
                                    Message 17 of 25 , Dec 12, 2004
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                                      Jerry,

                                      I've only seen a few late 500s apart, but they all were pretty decent
                                      as far as deck to piston. Assuming you have eom pistons and they're
                                      good shape, and a 40-50 thou gasket is used, a .020" to *maybe .025"
                                      deck cut will give you a nice tight assembled quench. El-cheapo cast
                                      replacement pistons are often 20+ thou shorter than oem. I would
                                      shoot for 040" assembled quench, regardless. Experts use either
                                      Felpro of Corteco gaskets. The Coretcos are a little better, but
                                      thicker, btw. .044"-.048" installed, iirc. You may need to stick the
                                      piston out of the hole a bit wioth those. The 472/500 heads can be
                                      cut way down. 050" is nothing on those, afaik. The 425 heads' deck
                                      isn't as thick, and experts say not to cut them much over 040".

                                      As far as rocker geometry, you can use shorter pushrods. You can also
                                      have a good stock cam re-ground, and that'll reduce the base circle a
                                      bit. Maybe enough to make up for the head/block cut. Most of the
                                      caddy parts vendors offer re-ground cams, btw, but most grinders will
                                      do one for you if you have a decent stock core. A note on that; most
                                      grinders want to use profiles with 10+ extra exhaust duration. Afaik,
                                      it's not needed on a caddy, esp with the 76cc heads. Even the 120cc
                                      heads' stock exhaust port flows well enough to allow same duration on
                                      intake and exh. Some experts even say that when ported, the caddy
                                      heads flow so well on exhaust side that they use a little less
                                      exhaust duration!

                                      As far as higher lift cams, you may need to snip a little from the
                                      top of the guides for clearance there. The '68 up seals are a joke.
                                      You can use the normal old umbrella valve seals from the '67 429
                                      caddys. SBchevy springs can be used, but you'll need to get creative
                                      with shimming. The caddy springs are very tall. The new behive
                                      springs offered for fords and LS1 chevs work better, with a retainer
                                      change, as they fit the caddy spring pad, and are taller than std sbc
                                      springs. If you have a freindly machine shop, they'll probably have
                                      some larger diameter used retainers from something that'll fit the
                                      behive springs. Just make sure they fit with the 11/32" valve
                                      keepers. Unlike the sbc or behive springs, larger o.d. springs will
                                      require pricey spring seats and more machine work. If you don't have
                                      a machine shop that you can trust, you might want to buy a spring
                                      package from one of the vendors. If you use stock rockers, choose a
                                      cam grind with nice slow ramps, as quick ramps are hard on the stock
                                      stuff. When cam shopping, make sure to tell them that you want slooow
                                      ramps. Fast ramps are hard on the stock T pedistals and rockers.
                                      Dave

                                      Brown" <jerome@p...> wrote:
                                      > Actually I was speculating about just milling the 500 heads to get
                                      the
                                      > increased compression ratio. Since the engine would be out of the
                                      car its no
                                      > big deal to pull the heads and have a valve job done and to mill
                                      them for
                                      > increased compression...So long as you don't booger up the valve
                                      train
                                      > ratios. It seems to me that if you mill the heads, say .040, that
                                      it would
                                      > drop the head lower with respect to the valve train i.e., closer to
                                      the
                                      > center of the camshaft, and might result in any of a number of
                                      unintended
                                      > results.
                                      > In order to keep everything in the same ratio you would have to
                                      account for
                                      > being .040 closer. Seems to me that pushrods that are .040 shorter
                                      should
                                      > compensate or taking .040 off the top of the valve stem might as
                                      long as the
                                      > keepers would still fit. Doesn't seem right that you wouldn't have
                                      to do
                                      > anything but mill to do the job right. Likewise decking the block
                                      would have
                                      > the same result of moving the head closer to the center of the cam.
                                      I guess
                                      > the right question is can milling or decking be done without
                                      unintended
                                      > catastrophic consequences and if so how should one compensate for
                                      the
                                      > changes.
                                      >
                                      > Jerry Brown
                                      >
                                      >
                                      > -----Original Message-----
                                      > From: jvandecreek25 [mailto:jvandecreek@c...]
                                      > Sent: Sunday, December 12, 2004 1:15 PM
                                      > To: Cadillac_Performance_Association@yahoogroups.com
                                      > Subject: [Cadillac_Performance_Association] Re: The '49-'62 V8...
                                      > anything out there?
                                      >
                                      >
                                      >
                                      >
                                      > --- In Cadillac_Performance_Association@yahoogroups.com, "david
                                      > brode" <dbrode@h...> wrote:
                                      > >
                                      > > Jerry,
                                      > >
                                      > > The '74-'76 500s have 120+ cc chambers and a very small dish. If
                                      > the
                                      > > bores look good, you could just deck the block for a .040" or so
                                      > > assembled quench, and whack the heads to get to *maybe* 9.5-1.
                                      > Fyi -
                                      > > KB makes no dish flat tops for it if it needs bored [which I doubt
                                      > it
                                      > > will].
                                      > >
                                      > > Another option would be dished KB designed for the early heads.
                                      > They
                                      > > give 10-2-1 or so with the '68-'73 heads [76cc]. Another option is
                                      > to
                                      > > use 107cc 425 heads on your shortblock. They'll put you a little
                                      > over
                                      > > 9.5-1. The 425 heads don't flow as well as yours, but a little
                                      > work
                                      > > and they'll do ok. The 76cc heads flow better than yours, btw, but
                                      > > not much in stock form. More fyi - 2.11"/1.66&1.77" pontiac valves
                                      > > fit the 107 and 120cc heads perfectly. For larger valves on the
                                      > 76cc,
                                      > > aftermarket valves are available from the caddy
                                      > > parts vendors.
                                      > > Dave
                                      >
                                      >
                                      > I'm looking for about 9.5:1 CR to help out performance. I know the
                                      > best way to go is usually different pistons but I'm trying to keep
                                      > the costs reasonable.
                                      > Jerry Brown
                                      >
                                      >
                                      > Jerry wanted to keep the costs reasonable, to "deck the block "
                                      > will require a complete disassembly, and is hardly a way to keep the
                                      > cost down, and as he stated he did not want to get into piston
                                      > changes.
                                      > I made my recommendation based on the premise that he wanted an
                                      > inexpensive power increase for a engine that was going into a street
                                      > rod, no it is not the 'ultimate' performance build up, but if it is
                                      > not being used as a race car, there is no need to pursue a lot of
                                      > expensive modifications that are unnecessary for strong street
                                      > performance. Jessie
                                      >
                                      >
                                      >
                                      >
                                      >
                                      >
                                      >
                                      >
                                      > Yahoo! Groups Links
                                    • david brode
                                      Preston, Good point. I ve decked a couple of them, but only 10-20. There was no need to cut the intake, or intake side of head. The intake may ride up on the
                                      Message 18 of 25 , Dec 12, 2004
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                                        Preston,

                                        Good point. I've decked a couple of them, but only 10-20. There was
                                        no need to cut the intake, or intake side of head. The intake may
                                        ride up on the heads a wee bit, but unless a large amount of mat'l
                                        was cut, the ports can be re-aligned when port matching.

                                        If it was a problem, the intake could be cut, or the intake side of
                                        the head, although the valve cover bolt hole bosses there make it a
                                        bit tricky.

                                        I know that this issue is common, as the .015" shorter 6.735" forged
                                        olds rods are often used in the caddy. Another old combo is 7" olds
                                        rods and 403" olds pistons. That combo is 40-50 thou short, so I'm
                                        sure it's been addressed.
                                        Dave


                                        III <prestoniii2002@y...> wrote:
                                        > I've never decked the block, or shaved the heads of a Caddy
                                        > engine, but if it's anything like a Chevrolet small block,
                                        > there's a limit that you can go before you have to do some
                                        > machining to the intake manifold too. I expect that if you
                                        > go past a certain extent, then you'll be in for spending
                                        > even a few dollars more!
                                        >
                                        > Don't forget to inquire as to whether the changing geometry,
                                        > and clearances of the intake/head surfaces may require a
                                        > specific gasket, such as something extra thick.
                                        >
                                        > Also, in a true performance application, you may consider
                                        > port matching the intake manifold to the intake side of
                                        > the cylinder heads, as this is the dimension that will change
                                        > as you go shaving things.
                                        >
                                        >
                                        > Preston III
                                        <snipped
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