"Boiling" Gas, 69 Tripower

[John M.]

Last night, after doing some carb adjustments, I noticed one of the carbs "gurgling" and dripping gas onto the throttle plates at a regular interval of around 10 seconds after the engine was shut down. It kept doing it for about 10 minutes. The engine was warm but not hot and only the rear carb did it. The float levels are good and the engine runs very well. Is this just the fuel boiling and pushing a little out through the idle circuit or ?? Thanks for any help.

[Joe Kayser]

Re: "Boiling" Gas, 69 Tripower

Had the same problem a few weeks ago myself. The fuel is pushing past the metering plate and into the throttle bore. Mine would spit a shot of fuel every few minutes just like yours. Either your metering plate is warped or you just need new metering plate and bowl gaskets.

You'll need two different gaskets, and you can get them both from Summitracing.com. Part #'s 108-90-2 and 108-27-2 (each package contains 2 gaskets, or enough for both carbs, so order one of each part #. You'll also need a "clutch" head screwdriver to remove the metering plates.

If you decide to completely rebuild each carb, these gaskets are included in the Holley rebuild kits.

[Juliet P.]

Re: "Boiling" Gas, 69 Tripower

I had the same exact situation with my former Q-jet. I was never able to resolve it or figure out why the gas was boiling. The carb had been rebuilt and was running well. It was not the correct carb for my '70. It was from a '69 Auto. Truck. I since found the correct / dated carb, rebuilt it and put that on the corvette. VOILA! No more boiling fuel. I didn't change a single thing other than the carb. One thing I noticed that was different between the incorrect and correct carb is a vent hooked to the throttle on the front of the correct carb. The old carb did not have any leaks that I could see externally. Both were checked with a machinist straight edge for warping at the base plate and both are fine. This is a wild shoot in the dark here, but I think it might have something to do with the pressure affecting the boiling point of the gasoline. Also I have not noticed any difference between the two in terms of how much pumping it takes to get enough gas in the carb before starting up after prolonged sitting (ie they don't appear to leak down).

Probably not much useful here other than sympathy. I'll definately follow this thread to see what others have to say about it.


Juliet's 1970 Corvette

[Jerry Clark]

Re: "Boiling" Gas, 69 Tripower

Hi Joe:

Remember, no metering plate on the secondary carburetors. Sounds like thermal expansion simply pushing the fuel into the throttle bores.

jer

[grr]

Re: "Boiling" Gas, 69 Tripower

John, call, Poney Carburetors,inc. their out of New York. I've done business with them and describe your problem and you shall receive an answer. Make sure you tell them if you have modified anything.The carb number,type,mfr.etc 315-662-3003.

With all the time and good info the members have given a call wouldn't hurt. Please let us know what you find causing the problem when you fix it. It only helps out the members when someone tells them what they had done to remedy a certain problem, especially a carb problem. I've got three of them also and my car will be coming out of layup (resto) soon so I expect some bugs. Best regards,grr#33570

[John M.]

Re: "Boiling" Gas, 69 Tripower

Hey Guys, Thanks for the responses. I took the carb off the car last night and found that the screws that hold the metering plate on were pretty loose. I have another gasket in my carb parts box and I picked up the clutch bit for the screws this morning. I'll call Poney Carburetors and let you all know what happens Monday. Thanks again.

[George Daina]

Another item to check....

float level and needle and seat. If your float level is to high, gas will dump. What controls the level is the needle. check your sight plug.

[Joe Kayser]

Re: "Boiling" Gas, 69 Tripower

Jerry, there is definitely a metering plate. What is missing from the secondaries is the Holley metering "block".