Re: Zenith/Bendix Carburetor
- Here's the book I have:
And here is another one:
Order them by going here:
and drilling down to Model A books.
It depends on how much fussing you want to do in the shop. Fixing the
needle on your Ultracarb will take about 3 hours. Installing the new carb
will take - who knows!? But 3 days or more is as good a guess as I can
manage. You'll NEED carb heat if you don't already have it. An air filter.
The manifold may need to be changed and the engine controls certainly will.
You sound committed, just reminding you what you're in for.
Ryan R Young
> From: "Bernard Melendez, Jr."
> You're a life saver and I really appreciate your
> prompt response. I'll try Google to try and find more
> poop on this carb. Mine is not cast iron but looks
> like cast aluminum. It also appears to be the same one
> that GPAS sells. I'd just like to get my Corby's VW
> running smooth and dependably. Seems like the Ultra
> carbs are finicky and who needs that? Sometimes I wish
> that I had built something with a Continental or Lyc.
> Anyway, Thanks for responding so soon. By the way, if
> you have an Aircraft Spruce catalog, there's a pic of
> my Starlet in it under the section that shows the
> material kits that they sell. Also there's some pics
> of it in some of the Corby Starlet sites. As they say
> here in Texas, "you'all have a good day, you hear?"
> Best regards,
> Bernardo Melendez, jr.
- I have a Zenith industrial carburetor (which is the replacement for the Model A)
on my 1700 cc VW. Setting the mixture is quite simple. If you have ever
adjusted the mixture on a lawn mower then you know how to tune the Zenith. An
in flight mixture modification would be to add an arm to the mixture screw but I
do not think it is necessary with the kind of flying we do with a VW engine.
Fri, 31 Jan 2003 22:09:00 -0800, you wrote:
>The true, original model A carbs had cast iron bodies and were quite heavy.
>I'm not sure what you have, it doesn't really sound like a model A carb.
>I have a book on model A carbs that covers the original Bendix and the
>Tillotson X, which is what I have, but haven't overhauled, installed, or
>tuned. You can get the book (and rebuild kits) from any of the several
>parts houses that stock stuff for Model A's, a few of which are online. See
>Dr. Google to find them. The book is $5 and is worth it.
>The mixture adjustment is NOT on the levers, which control the choke and
>throttle butterfly valves. The mixture adjustment is a screw deal on these
>carbs. Poke around a bit - there may be an idle air screw as well, which
>will affect the idle mixture and speed.
>If you need a broader mixture adjustment, get a set of tiny number drills.
>Take the carb apart to find the main jet. Use the drills as gauges to see
>what size the jet is, then either drill it out (richer), or fill the whole
>with silver solder, and drill it smaller. Be careful when re-assembling the
>carb to make sure the jet stays put, use the weakest Loctite (you will
>probably need to take the thing apart again sooner or later...).
>As far as tuning goes, I think the easiest would be to get a mixture gauge
>that runs off the exhaust, and set the deal well rich of stoichometric. A
>Colortune (brand name) is a cheaper way to go - runs in a sparkplug, but it
>would be tricky trying to read it with a spinning prop inches away.
>The real problem is getting a carb that runs well at ALL throttle settings.
>Have you looked at my POSA page?
>It applies to Ultra Carbs too - same issue, linear taper of the needle on a
>hole that opens in a non-linear manner.
>But then there is the starting ritual with the POSA - both the cold start,
>and the hot start. I used to have Ed Sterba's ritual for his Sonerai, but
>no longer. Perhaps you can get it from the Sonerai Newsletter editor, Fred
>Keip, contact Fred at 11428 Six Mile Road, Franksville, WI 53126.