I give up

[Woodie1]

Our 1930 A will not idle down without quitting. I have plugged the vacuum wiper connection at the manifold & it made no difference. I removed the intake manifold & filed the connection for the carb flatter & installed new carb gaskets at the bowl & mounting flange. I have removed all jets & made sure they were clear. The float level looks correct. With the upper half upside down I measure 1 1/4" to the gasket surface from the solder line & it measures even on sides & front of float. The timing is good. The engine is a touring engine with high compression head & has about 5ooo miles on it. The throttle shaft is free in the housing with no slop. It's been dying at stops lately. It wasn't doing this before. I have always had it idling a bit fast but now it's worse. I just don't know what else to try. The carb was rebuilt by a reputable Model A parts supplier about 4 years ago. It doesn't drip gas when sitting. I do shut the gas off. when done driving it.

[bobbader]

Easy answer #1. If he's still around, contact the carburetor rebuilder (or the vendor you bought the rebuild from). Hopefully, they can make suggestions.

If you just bought a new Ford, I'm assuming for the first servicing, you would not call the Chevy dealer.

Not trying to be a wise ass and I mean no disrespect, but a good rule of thumb ............ if the item functioned properly until now and you were pleased with the work done, why not go back to the guy that did the work?

[1930artdeco]

You said that you removed the intake. But did you remove the exh. and have them both planed? Is either of them cracked? What about gland rings to keep the exh. manifold from sagging?

Just my 2 cents,

Mike

[Woodie1]

The manifolds were machined together a number of years ago. No gland rings though. Never had luck getting them to seat well. I'm not convinced the carb is the issue. I can put another carb on & the car runs the same way.

[Gary WA]

Originally Posted by Woodie1

Our 1930 A will not idle down without quitting. I have plugged the vacuum wiper connection at the manifold & it made no difference. I removed the intake manifold & filed the connection for the carb flatter & installed new carb gaskets at the bowl & mounting flange. I have removed all jets & made sure they were clear. The float level looks correct. With the upper half upside down I measure 1 1/4" to the gasket surface from the solder line & it measures even on sides & front of float. The timing is good. The engine is a touring engine with high compression head & has about 5ooo miles on it. The throttle shaft is free in the housing with no slop. It's been dying at stops lately. It wasn't doing this before. I have always had it idling a bit fast but now it's worse. I just don't know what else to try. The carb was rebuilt by a reputable Model A parts supplier about 4 years ago. It doesn't drip gas when sitting. I do shut the gas off. when done driving it.

Have you checked Idle Air adjustment screw(mis-adjusted or too short) or dirt/rust. Next time it dies stop and remove gas line to ensure it is getting fuel and not plugged with rust??

[Woodie1]

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I don't see any trouble with the air idle adjustment. The threads seem snug. As for the length, I don't know if it's too short or long.

[Gary WA]

Originally Posted by Woodie1

The manifolds were machined together a number of years ago. No gland rings though. Never had luck getting them to seat well. I'm not convinced the carb is the issue. I can put another carb on & the car runs the same way.

Just saw another carb installed doing the same thing.! Cast iron fuel filter or glass bowl? Also installing fuel line into carb too far will restrict fuel flow!

[mleder]

Woodie: You kind of answerd most of the problem in your post #6. 2 different carbs runs same way. Unlikely its the carburetor, could be a valve issue but leaks in and around manifold deserve a good second or third look

[JayJay]

Originally Posted by Woodie1

The manifolds were machined together a number of years ago. No gland rings though. Never had luck getting them to seat well. I'm not convinced the carb is the issue. I can put another carb on & the car runs the same way.

This ought to be a clue that the problem is likely not carburetor. This sounds to me like a vacuum leak, not a fuel starvation (that would tend to be apparent under load, not at idle). Are you sure you're not leaking around the intake manifold? If I was in your shoes that would be the next thing I'd try - pull the intake/exhaust manifold assembly, check for flatness, and install new copper gaskets (I like the two-piece '31 style). Also check for exhaust manifold sag, this can pull the rear of the manifold down and expose both intake and exhaust ports. Your difficulty with gland rings might point to a sagging manifold...

Also, carb to manifold gasket should be the thick copper style. I've had limited success with the pressed ones.

[Banditorama]

Run the engine as low as you can where it runs smooth, take a can of starter fluid and give a quick spray where the intake meets the engine. If the RPMs change you've found your culprit.

[Woodie1]

The engine was rebuilt as a touring engine 3 years ag. I wouldn't think there are valve issues yet after 5000 miles. I did replace the manifold gaskets a couple of days ago with the copper round gaskets. The exhaust manifold was new maybe 8 years ago & I had the exhaust & intake manifolds trued up at that time. I did not check for a good match of the manifolds this time. Vacuum leaks are associated with the intake only or am I wrong one this?

[1crosscut]

Do as mentioned in post #10.
Spray starter fluid all around the manifolds when it is running and listen for a change in engine speed.

When installing manifolds I loosen the two bolts that hold the intake manifold to the exhaust manifold and tighten them after the manifolds are tightened to the block. This allows them to float a bit and seat better.
Be sure to tighten the four manifold bolts a time or three after the engine runs through a few heat cycles.

If the carburetor you switched to came off a good running car then the carburetor is not your problem.

Do you have a plastic inline fuel filter installed. They can cause problems.

Does your fuel line run downhill all the way to the carburetor? I've found having a fuel line loop down and then run uphill to the carburetor can cause problems.

[Woodie1]

The fuel line is an original style. No rubber hose & no up hill bends. I have a glass sediment bowl & keep it clean. I tried a propane torch unlit around the manifolds & heard no change in speed.

[Gary WA]

Originally Posted by Woodie1

The fuel line is an original style. No rubber hose & no up hill bends. I have a glass sediment bowl & keep it clean. I tried a propane torch unlit around the manifolds & heard no change in speed.

Just for idea? Gas cap properly vented!

[Woodie1]

Gas cap is vented.

[Rob Doe]

Where does the term 1-1/4" come from? I've never seen that before, anywhere. All I've ever seen is 1" or 15/16". Verify that the fuel level (not the float height) in the float bowl is correct. Measure and set the fuel level 5/8" below the fuel bowl gasket surface using an external sight gauge.

Stalling on stop has a lengthy list of things that can be the cause. Has the idle speed adjustment screw backed out, allowing the throttle plate to close completely?

[1crosscut]

Propane torch might show a leak with the fan belt off so there is no airflow from the fan.
Starting fluid is much more telling. Never had a problem with it flaming up while testing with it.

[CT Jack]

I would try adjusting the float valve by using various shim thicknesses. Sometimes a small shim thickness change will improve low speed performance especially when abrutly stopping.
I would also check the distributor rotor runout. It might be in need of new bushings. If runout is significant it can change the point gap which could be most noticeable at low rpm.

[Woodie1]

I'll have to check the distributor run out. I was sure I rebuilt it when I had the engine rebuilt.

[Woodie1]

I just checked the distributor. There isn't any wobble of the shaft but there is about .018 up & down movement of the shaft. Could this be some of the idle problems?