Loading ...
Sorry, an error occurred while loading the content.

Re: Carburetors

Expand Messages
  • winchesterman50
    Checked my reference book (http://www.cartechbooks.com/vstore/showdetl.cfm?st=0&st2=0&st3=0&CATID=23&Product_ID=3602&DID=6) There were 2 basic Q-jet bodies.
    Message 1 of 14 , Oct 29, 2010
    • 0 Attachment
      Checked my reference book (http://www.cartechbooks.com/vstore/showdetl.cfm?st=0&st2=0&st3=0&CATID=23&Product_ID=3602&DID=6)
      There were 2 basic Q-jet bodies. One was rated at 750 CFM, the other at 800 CFM. The 750 (1 3/8" primary) is the one you typically see.

      This is also supported by this site:
      http://www.carburetor.ca/carbs/tech/Rochester/Quadrajet-index.html
      Which says:
      The QJet is a large 4 barrel carburetor that has a small primary side for fuel economy and good emissions and a large secondary side for good performance. QJets have a maximum airflow of from 750-800 cfm. Because the secondary side of the Qjet opens according to the airflow requirements of the engine, the same basic carburetor size can be used on a large range of engine sizes. The basic 750 cfm QJet casting is used from 231 CID to over 400 CID - the big secondary air valves open only as the engine breathes. For example, on a mild 350 Chevy the air valve will never open all the way - because the motor can't use more than 600 cfm or so.

      You will also notice that the rebuilt Q-jets at Summit are also rated at 750 CFM.
      http://www.summitracing.com/search/Product-Line/Summit-Racing-Remanufactured-Quadrajet-Carburetors/?keyword=Q-jet&autoview=SKU

      I have no reason to doubt these sources. Please make your own deductions from them.

      Dave
    • gmmullins4
      very rarely would you find the 4MV carb on a vehicle engine, it was mainly developed for boats, but was used on 396 engines and some 403 and dodge vehicles.
      Message 2 of 14 , Oct 30, 2010
      • 0 Attachment
        very rarely would you find the 4MV carb on a vehicle engine, it was mainly developed for boats, but was used on 396 engines and some 403 and dodge vehicles. m4m started in 75 went through 79.e4m started in 79 and went through till they were no longer used.

        m4v have the coil in the intake, 4mc/m4mc have a tube to take heat from the intake and coil on the carb, the m4me is the first to use an electric coil on the carb.

        a 4mv has a shorter butterfly shaft for primaries than the other carbs as well and bolt pattern is ever so slightly smaller. and had a smaller fuel inlet as well, 7/8" by 20

        in 1980 you will find e4me carbs starting to be used. (computer controlled carbs

        in 85 the m4med which had a dual capacity pump solenoid used on fed trucks and canadian vehicles

        also in 85 you will find a m4mef used on 454 with hd emissions and california only truck frames

        for older 73-78 carbs used on gmc motorhomes since they have a different set up, here is a place to look up info on them. http://www.newagemetal.com/pages/GMC/73-78GMC.pdf

        for 63-70 truck chassis:
        http://www.newagemetal.com/pages/ChevroletTruck/63-70Chev.pdf

        for 71-80 truck chassis:
        http://www.newagemetal.com/pages/ChevroletTruck/71-80Chev.pdf

        for 63-80 parts lists:
        http://www.newagemetal.com/pages/ChevroletTruck/servicecarbs.pdf

        what you will find for variations is every year might have an extra vacuum control off the carb, or the placement of different tubes and the way the throttle is made. you would be hard pressed to use a 73 carb on a 84, and vice versa. but if you were savy enough with engine could remove the smog off a newer one and gain some horsepower. of course computer controlled carbs are not adjustable in any manner, and finicky at best.




        --- In classicrv@yahoogroups.com, "winchesterman50" <winchesterman50@...> wrote:
        >
        > 4MV style Quadrajet (spreadbore) had the coil portion of the choke embedded in the intake manifold. Linkage from the choke coil attached to the carburator.
        >
        > 4MC style Quadrajet (spreadbore with Climatic Choke) had the choke coil mounted in a housing attached to the side of the carburator. A heat riser tube attached to the choke housing.
        >
        > Edelbrock 1406 is a square bore carb (requires an adaptor to mount on spreadbore manifold) with electric choke. You would have to add a wire from ignition side to make the choke work. Edelbrock no longer makes a spreadbore version (1900 series). You can pick them up rebuilt/used on EBAY.
        >
        > If memeory serves me correctly, most quadrajets were rated around 750-800 CFM. The Edlebrock 1406 is only rated at 600 CFM. I will check my Rochester reference book when I get home.
        >
        > Dave
        >
      • gmmullins4
        in that year the climatic choke was only used on dodge, not chevy, yours should have an electric choke and thats what the e means on the end. i posted the
        Message 3 of 14 , Oct 30, 2010
        • 0 Attachment
          in that year the climatic choke was only used on dodge, not chevy, yours should have an electric choke and thats what the 'e' means on the end. i posted the different uses in another post so you can look at them there.

          --- In classicrv@yahoogroups.com, "DanielM" <dmiller_nowlin@...> wrote:
          >
          > Well, since I'm in the market for a new Quadrajet for my 1984 Holiday Rambler,I went to their website and was quite impressed. My truck center installed a new Edelbrock Performer Series 1406 on my 454Chevy engine. But, the Edelbrock just doesn't put out the power the Quadrajet did. The NationalCarburetors site says my Quadrajet should have a Climatic Choke. I don't know what that is and I thought I just had an electric choke. Could someone enlighten me on the difference? It is supposed to be an M4ME carb.
          >
          > --- In classicrv@yahoogroups.com, "Sirrobyn0" <sirrobyn0@> wrote:
          > >
          > > Just wanted to give you all a quick heads up. First let me start by saying that I am the kind that always rebuilds his old carburetor himself. I have never had much luck with parts store rebuilds and find that my own job is usually a better one. I use to take my carburetors to a special carb. shop in the area if there work needed to be done and that was beyond what I could do at home but the old guy that ran the place retired and closed the business, so that is no longer an option. Well recently I decided to rebuild the carburetor on the motorhome (Dodge 360 Holley) and found that the throttle shaft bushings were shot. Not wanting to buy a typical parts store reman unit I looked to the internet and after some looking around decided to give National Carburetors a try http://nationalcarburetors.com/, I figured it wouldn't be any worse than a parts store carb and it was cheaper, if it was a total bomb I could just use there base plate on my carb. Well guess what, it was a top notch carburetor. I feel like I couldn't have done it better myself, and that is saying a lot because I like my rigs to run near perfect. Just had to set the idle mixture, tweak the choke and go. I'd highly recommend there guys based on this experience. Oh, I'll be taking the motorhome on a 400 mile round trip this coming weekend (towing a trailer loaded with Halloween stuff of course)to the Olympic peninsula so that will be the real test. Anyhow, I just thought I would pass on a good experience.
          > >
          > > Rob
          > >
          >
        • gmmullins4
          if you had looked farther you would have found what most carbs guys do is install larger bushings to restore tightness of the throttle shaft, this happens alot
          Message 4 of 14 , Oct 30, 2010
          • 0 Attachment
            if you had looked farther you would have found what most carbs guys do is install larger bushings to restore tightness of the throttle shaft, this happens alot with carbs whne they wear out the metal around the shaft.

            --- In classicrv@yahoogroups.com, "Sirrobyn0" <sirrobyn0@...> wrote:
            >
            > Just wanted to give you all a quick heads up. First let me start by saying that I am the kind that always rebuilds his old carburetor himself. I have never had much luck with parts store rebuilds and find that my own job is usually a better one. I use to take my carburetors to a special carb. shop in the area if there work needed to be done and that was beyond what I could do at home but the old guy that ran the place retired and closed the business, so that is no longer an option. Well recently I decided to rebuild the carburetor on the motorhome (Dodge 360 Holley) and found that the throttle shaft bushings were shot. Not wanting to buy a typical parts store reman unit I looked to the internet and after some looking around decided to give National Carburetors a try http://nationalcarburetors.com/, I figured it wouldn't be any worse than a parts store carb and it was cheaper, if it was a total bomb I could just use there base plate on my carb. Well guess what, it was a top notch carburetor. I feel like I couldn't have done it better myself, and that is saying a lot because I like my rigs to run near perfect. Just had to set the idle mixture, tweak the choke and go. I'd highly recommend there guys based on this experience. Oh, I'll be taking the motorhome on a 400 mile round trip this coming weekend (towing a trailer loaded with Halloween stuff of course)to the Olympic peninsula so that will be the real test. Anyhow, I just thought I would pass on a good experience.
            >
            > Rob
            >
          • Sirrobyn0
            Gmmullins, I would have gone that route if I could have, unfortunately the last carb. shop in my area closed down last year. So I thought rather than driving
            Message 5 of 14 , Oct 31, 2010
            • 0 Attachment
              Gmmullins,
              I would have gone that route if I could have, unfortunately the last carb. shop in my area closed down last year. So I thought rather than driving 75 miles to the next nearest place that I don't know the reputation of I'd go this other route. I can do the actual overhaul myself but I've never tried replacing the bushings before, maybe I'll try it next time but probably not as National Carbs did well for me.

              Rob

              --- In classicrv@yahoogroups.com, "gmmullins4" <gmmullins4@...> wrote:
              >
              > if you had looked farther you would have found what most carbs guys do is install larger bushings to restore tightness of the throttle shaft, this happens alot with carbs whne they wear out the metal around the shaft.
              >
              > --- In classicrv@yahoogroups.com, "Sirrobyn0" <sirrobyn0@> wrote:
              > >
              > > Just wanted to give you all a quick heads up. First let me start by saying that I am the kind that always rebuilds his old carburetor himself. I have never had much luck with parts store rebuilds and find that my own job is usually a better one. I use to take my carburetors to a special carb. shop in the area if there work needed to be done and that was beyond what I could do at home but the old guy that ran the place retired and closed the business, so that is no longer an option. Well recently I decided to rebuild the carburetor on the motorhome (Dodge 360 Holley) and found that the throttle shaft bushings were shot. Not wanting to buy a typical parts store reman unit I looked to the internet and after some looking around decided to give National Carburetors a try http://nationalcarburetors.com/, I figured it wouldn't be any worse than a parts store carb and it was cheaper, if it was a total bomb I could just use there base plate on my carb. Well guess what, it was a top notch carburetor. I feel like I couldn't have done it better myself, and that is saying a lot because I like my rigs to run near perfect. Just had to set the idle mixture, tweak the choke and go. I'd highly recommend there guys based on this experience. Oh, I'll be taking the motorhome on a 400 mile round trip this coming weekend (towing a trailer loaded with Halloween stuff of course)to the Olympic peninsula so that will be the real test. Anyhow, I just thought I would pass on a good experience.
              > >
              > > Rob
              > >
              >
            Your message has been successfully submitted and would be delivered to recipients shortly.