Holley 94 Carb on 34 engine

[34 fordor owner]

I can’t get my Holley 94 to run well. I’ve messed with idle mix and throttle and it keeps popping and sounds like a pssss sound like a vacuum leak and exploring into that it sounds like it’s from inside the carb. Any tips on this? Still popping in 2nd gear and on pulls.

[Ziggster]

Vacuum leaks can come from any number of areas. If the throttle shaft is loose, air can sneak past it and the shaft thru holes in the base. Warped diecast pcs can also be a source of leaks. Of you’re getting a back fire, chances are the PV seal has been blown resulting in gas leaking straight out of the fuel bowl into the intake.
Has it been rebuilt recently? I’ve rebuilt a couple recently, and there was lots of debris/dirt/etc in most of the fuel passages in the towers/brass needles. Also, you might want to check the accelerator pump function.

[34 fordor owner]

Originally Posted by Ziggster

Vacuum leaks can come from any number of areas. If the throttle shaft is loose, air can sneak past it and the shaft thru holes in the base. Warped diecast pcs can also be a source of leaks. Of you’re getting a back fire, chances are the PV seal has been blown resulting in gas leaking straight out of the fuel bowl into the intake.
Has it been rebuilt recently? I’ve rebuilt a couple recently, and there was lots of debris/dirt/etc in most of the fuel passages in the towers/brass needles. Also, you might want to check the accelerator pump function.

It has been rebuilt twice in about 3 years I think. Last time was a little over a year ago. I could get it rebuilt again but with both rebuilds it has popped while driving under a load and sounded of a small vacuum leak somewhere. I have a tuned “by ear” turn the screws in until it bogs then half to 1 turn out. I might need to set the idle throttle screw back some. I have a video of it running today I will share.

https://youtu.be/RjSSOsBhMN0?si=J1EaxBub20LMcZAn

[tubman]

Sounds like typical Holley power valve problems. Where have you been getting your kits. You might want to try to get a couple of correct stock power valves from "Charlie NY" or maybe even Daytona Parts.

[marko39]

Have you used a vacuum gauge? This can tell you a lot.

[Mart]

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Is it on the 34 intake manifold? Does that manifold have a hole in it on the carb mounting face? That hole is for manifold heat when using a stromberg. 94s won't work with that hole there.
Just a suggestion to check and eliminate if no hole.
Mart.

[38 coupe]

Are you sure your ignition is good? Many of the perceived carburetor problems turn out to be ignition problems (and vice-versa).

[34 fordor owner]

I haven’t rebuilt the carb my self I have sent it off to a preferred rebuilder from here. I’m not sure about and hole and I’m not sure that there are any places to hook a vacuum gauge up to on my engine? I will be working on it to is afternoon and will check these out.

[Terry,OH]

Since your not running the proper 34 Carb. You may not have the proper 34 intake manifolds. Removing the Carb. will expose the surface as mentioned in post #6 above. If there are 6 holes ( three for mounting studs, two for the Carburetor output and one for exhaust gas. The gases will come out and into the 94 overheating the power valve and causing the symptoms you are experiencing.

[FlatheadTed]

Make a gasket out of copper to cover the hole ,power vale leak through into the 34 manifold , do not ask me how I know ,Ted

[34 fordor owner]

Okay this may be the case of having an improper mounting base. Would this extra hole be on the intake manifold itself or would it be on the bottom of the carb? I don’t have any extra ports on the carb itself. I will need to pull the carb and check and probably rebuild it again as well. I dropped the throttle screw back some today and the idle screw on a turn or 1/2 turn out from the engine dying. There are small pops coming from the exhaust every once in a while, like unburnt gas. After I take a look into the carb this may sort itself out.

https://youtu.be/hHCgazDEQ8c?si=WeEbopRxh4G746iD

[34 fordor owner]

Originally Posted by 34 fordor owner

Okay this may be the case of having an improper mounting base. Would this extra hole be on the intake manifold itself or would it be on the bottom of the carb? I don’t have any extra ports on the carb itself. I will need to pull the carb and check and probably rebuild it again as well. I dropped the throttle screw back some today and the idle screw on a turn or 1/2 turn out from the engine dying. There are small pops coming from the exhaust every once in a while, like unburnt gas. After I take a look into the carb this may sort itself out.

https://youtu.be/hHCgazDEQ8c?si=WeEbopRxh4G746iD

Okay I looked up some pictures and I see the extra small hole that has been mentioned above. If I have a proper gasket that would not include that hole, like a stromberg gasket, it could solve the issue if that hole is there?

[34 fordor owner]

Originally Posted by 34 fordor owner

Okay I looked up some pictures and I see the extra small hole that has been mentioned above. If I have a proper gasket that would not include that hole, like a stromberg gasket, it could solve the issue if that hole is there?

Here are two spare gaskets I have, I should be used the bottom with no hole, right?

[34 fordor owner]

Originally Posted by 34 fordor owner

Here are two spare gaskets I have, I should be used the bottom with no hole, right?

Sent from my iPhone using Tapatalk

[Terry,OH]

If the gasket is made of paper, the hot gas will burn through. If metal and asbestos OK.

[34 fordor owner]

Originally Posted by Terry,OH

If the gasket is made of paper, the hot gas will burn through. If metal and asbestos OK.

Okay that gasket (bottom in picture) is thicker than any others I have used and does not have that extra hole. Basically if I have a Holley 94 on a 34 intake I do not need that hole in the gasket? Also notice my gasket on the carb now is hanging over… odd.

[ford38v8]

Originally Posted by 34 fordor owner

Okay that gasket (bottom in picture) is thicker than any others I have used and does not have that extra hole. Basically if I have a Holley 94 on a 34 intake I do not need that hole in the gasket? Also notice my gasket on the carb now is hanging over… odd.

On this subject of that heat riser hole in the manifold, a problem noted for many years has been dealt with in this manner:

Remove the manifold from the engine, and obtain old wheat stalk pennies to tap into the two heat riser holes in the engine block, one on each cylinder bank. (Wheat stalk pennies are required due to their metallurgy) On the manifold, these two holes converge at the top to pre-heat the fuel in the carburetor, which with modern fuel is radical overkill. The insertion of pennies closes off and eliminates the heat riser through the manifold altogether, which does several things:
It creates a vibrant exhaust rap (if you also have dual exhaust pipes).
It takes a few minutes longer to warm up the engine in the morning.
It helps protect the power valve from damage.
it goes a long way toward preventing fuel starvation issues caused by heat soak.

A reasonable compromise to the above method is to drill ⅛" holes in the wheat stalk pennies. In both cases, the pennies are gently tapped into the holes until flush with the top surface.

[FlatheadTed]

Also remove the mixture jets and suck on them holes with a vacuum cleaner ,you also could remove the carb bend up a length of mig wire to 3/8 right angle and prob the holes inside near the throttle plate , Finnish with air ,Ted