I have been experiencing the typical hard start after the engine has warmed up problem. I have a '57 Skyliner with a rebuilt 292 with a 4 barrel Autolite carb and after a drive, if I shut it off and try to restart after a few minutes, it takes quite a few cranks to get it running again. I've read alot of posts on this problem and one solution is to use a phenolic spacer under the carb to decrease heat transfer to the carb. I currently use a 1/2" aluminum spacer with a vacuum port to the PCV valve. Does anyone know of a similar phenolic spacer compatible with my carb that has that vacuum port?

I can’t help with the spacer, but something I learned on my bird was that if I opened the hood I didn’t have that problem. Closed, I did. Confirms it’s heat related. If that’s the case and it runs well hot, it might be under hood heat rather than heat transfer.

miker
55 bird, 32 cabrio F code
Kent, WA
Tucson, AZ

You don’t say how much time has elapsed since the carburetor has been rebuilt but this sounds like this could a carburetor issue.  Some things to look for within the carb would be a leaking power valve or power valve gasket, stopped up anti-siphon hole(s) which are located in the tops of the fuel discharge boosters, fuel inlet needle seats leaking by, brass fuel float that has leaked some fuel into it, a black nitrofil fuel float that is becoming fuel saturated, or just high float levels.  A combination of any of these makes finding the fix more complicated.

Lorena, Texas (South of Waco)

This rebuilt engine and carb have less than 100 miles on them. It starts easily when cold and runs great when warmed up. If I shut off the engine and restart within a couple of minutes, no problem. If I restart after 10 or 15 minutes, I've got to pump the pedal to get it going again. Seems like the gas is boiling off. Was also thinking of trying a thicker heat insulator gasket under the spacer.

Do You sufficient Hood clearance to ad a Phenolic Spacer on top of the Aluminum One? May require longer Studs but would likely help with keeping Heat Transfer from the Carb. The Aluminum PCV Plate is conducting heat from Intake to Carb. Phenolic Spacers come in different Thickness' from 1/4 Inch and up.

  

Since I'm using the original air cleaner, I can't add any height to the carb/spacer. I'm wondering now if that slightly thicker insulating gasket might help.

What you are experiencing is after shutdown heat soak. It causes the fuel in the supply line and/or carb t expand and flood the carb.

A phenolic spacer is available (.028" H w/ I/2" PCV connection) but is priced high. You might want to start trying to correct heat soak with a insulating base gasket. This will go between the ALUM spacer and carb body.

CARB BASE GASKET - 1/4" Insulating - Reinf Corners - HOLLEY PN 108-58

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... hmmpf ...

No further comments? I would think HOT SOAK - FUEL PERCOLATION would draw more interest.




SOURCE -

[Gasoline Hot Soak - ShopTips NOV 63 #10

The problem(s) today are even more severe with ETHANOL blended fuels.

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