Carb. Adjustment

[Cape Codder]

The car is running rather well EXCEPT when I go to stop at a light/stop sign it quits on me. Is this a float problem and if so do I put a gasket under the float shut off or add one?

[Synchro909]

Originally Posted by Cape Codder

The car is running rather well EXCEPT when I go to stop at a light/stop sign it quits on me. Is this a float problem and if so do I put a gasket under the float shut off or add one?

I will assume you are running a Zenith carburettor.
Your problem might be float level. It might be an air leak. It will almost certainly be one or the other. I believe in checking the easy things first. I suggest you try spraying some starter fluid around the manifold, carb flange etc - anywhere there may be a leak and listen for a change in the sound of the engine. If it changes, you have found the problem. If that is negative, go to the carburettor and check the float level. It may be too high, in which case, you should correct it by adding a washer under the valve.
I'm sure other will also rrespond.

[1930artdeco]

When I run zenith I make sure to leaver her at least 1/4 open or she will stall out! On the freeway I close her down but around I leave her 1/4 open. It is a design issue with the bowl.

Mike

[JD 1931]

It might be float level, add another gasket to float valve then check float so it is parallel to top body when upside down.

[JD 1931]

Above post is for a Zenith Model A carb.

[MALAK]

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Tom Endy did a great article on this.

My A used to do the same thing. Cleaned out the idle passages per the article and no more problem.

http://www.santaanitaas.org/wp-conte...p-Oct-2011.pdf

http://www.santaanitaas.org/wp-conte...-At-a-Stop.pdf

[Cape Codder]

Thanks to all for your suggestions. I first took Synchro909sugestion about spraying starter fluid and found a change in sound in the front & rear of the exhaust manifold, the area of the carb. gasket and exhaust manifold to the exhaust pipe. BUT my question to you is it seemed as though it was losing RPM rather than gaining RPM. Does it matter? I have just a little over 10,000 miles on the rebuilt engine and had the exhaust/intake manifolds and intake where the carb. is installed with NEW gaskets!

[Brentwood Bob]

Snug up the manifold bolts and a new gasket for carb to intake.
The manifold gaskets could now need replacement.

[duke36]

Blocking the leaks with spray perhaps could richen the mixture slowing down the idle, etc. without adjusting the carb. Check all areas as mentioned by others, and so as not to burn valves with too lean a mixture. Check if there is any tell tale black/gray exhaust blowby at the manifold to tailpipe clamp also and the rear tailpipe clamp is loose enough to allow expansion..

[Jacksonlll]

Use a big file and clean up the two flanges. Carb and where it attaches to manifold. You will probably find them not flat. File them until the whole surface is shiny. I have fixed many this way.

[Cape Codder]

As I said in an earlier post I took Synchro99 suggestion and changed the Exhaust Manifold Gasket after finding it had couple area's of leakage and also the Carb. gasket. Car does run really nice now. Just hope it stays that way as I will be on my way to the New England Meet in two weeks from tomorrow, Wednesday!

Thanks to all for your input and suggestions.

[Dino's A]

Did it run good before or has it always did this?

[Brentwood Bob]

Heat cycles and steel manifold nuts will lead to loose manifolds. Brass nuts are available thru snyder’s. The head nuts are another place to check, especially if you pulled the head.

[Cape Codder]

I had problems with it at Gettysburg last year but was able to drive it home. Prior to that I hadn't had a problem since I had the motor rebuilt approx 10,300 miles ago.

I have always used brass nuts on the manifold studs and always thought that was the only way it was.