VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1929-1932 I have a 30 with a 32 intake and 28B Zenith downdraft

I have a 30 with a 32 intake and 28B Zenith downdraft. It has been rebuilt. For the life of me I can't adjust it where it is not rich at idle. It runs great on the road, but it fumes me out almost to the point of being drunk. I don't know what I am doing wrong. Any help would be greatly appreciated.

Thank you

I'd check the float level and make sure that the float actually floats.

I once had a car that had that exact problem. Ran like crap and blew black smoke at idle and low speed. Ran fine on the highway. Turns out that the float didn't. Replaced the float and the car fan like it should.

Thank you. Unfortunately, my float floats.

define rebuilt... (rebuilt is a relative term)
and by whom ??

I bought a kit for it and it was rebuilt by a Harley-Davidson motorcycle mechanic.

Try to see if you can find a later W-1 carter as you may be over jetted on the zenith, and it is just allowing too much fuel in, A carter 569-S. Is what is the recommended replacement carburetor for a 1932 . If you can find one with the Zee throttle arm it can be straightened to make it flat and redrill the end hole.

SOME of the Zenith downdraft carbs have an inverse idle circuit. Clockwise (in) is RICH, counter-clockwise (out) is lean.

Since it runs well on the road, and is just rich at idle, you might check for the above.

Jon.

Steve messaged me asking if he could bring the carb to me.

Unfortunately, government regulations (insurance) has forced us to be mail order only (no walk-in customers).

However, will still try to help.

Lots of folks confuse the Zenith 28 series (inverse idle circuit)

https://www.thecarburetorshop.com/Zenith_type_28_exploded_view.jpg

with the Zenith 228 series (normal idle circuit)

https://www.thecarburetorshop.com/Zenith_type_228_exploded_view.jpg

Note that item number 20 is the idle mixture control screw in each view. The type 28 has the screw at the top, whereas the type 228 (improved) has the screw at the bottom. The 28 idle mixture screw meters air only, whereas the 228 idle mixture screw meters a fuel/air mixture.

Jon.

Thank you. That clears things up for me. Let me ask you this. Do you think that is the correct carburetor for a 194 cu. in. Chevrolet motor?

Without knowing exactly which Zenith carburetor and how it is jetted all we can do is guess. We do know that a Carter W-1 569s is the replacement carburetor for 1932-36 Chevy engines. It is a little leaner than the original W-1 212s or 222s or 235s so should work well. The '32 is a 194 the others 207.

Don't happen to have one, do you?

Zenith carburetors (mostly) are identified with a round tag approximately the size of a dime which is riveted to the body of the carburetor. Often, there are two circles of number, with the outer circle being an O.E. part number (for example, G.M.C. or I.H.C.) and the inner number being the Zenith part number.

If we knew the number, we would have a better idea of the applicability of the Zenith to your engine.

Personally, I like the Carter W-1 which others have mentioned in this thread; but Zenith made excellent carburetors. It just remains to be seen if yours is applicable, or not.

Jon.

Jon

The outer no. is 76560 R92
Them inner no. is 10738A

Hope that means something to you.

Steve

I would not suggest this one for your application.

It should run really well on a pressure 235.

Jon.

Jon

Do you have anything that will fit my application properly? 32 intake on a 194 cu.in., or is there any way to re jet this one?

Steve

Steve - well actually, after my second cup of coffee, and changing the battery in my calculator, I think what you have will work OK, you just need to adjust it. And please delete my comment about it working on a 235 from your memory.

EDIT: Carter uses S.A.E. measurement, and Zenith uses metric. Either the calculator battery, my artificial eyes, or my fingers which are bowed from hauling too much hay (good excuses, right - I screwed up ) caused me to see an incorrect figure when doing the conversion.

Jon

Jon

I think I have tried every combination and it is still idling rich. Can you tell me if it has a main jet, if so, can you tell me where it is located?
Do you have a Carter1 569s?

Steve

The main jet has nothing to do with idle. How far out is the idle mixture screw?

Jon.

Almost all of the way. Maybe two turns from coming out.

Fuel pressure? Electric fuel pump?

Pertronix conversion in distributor and still running a generator?

Factory fuel pump. Haven't checked the pressure