Heat Soak

[dodj]

I recently replaced my Holley 3310-750 with a QFT BD-850. The holley always leaked a little fuel into the intake when the engine was shutdown. The QFT boils it out about 15 minutes after shut down. The carb is cool when shut down, but heats up as time passes and then boils some fuel out. More out of the secondaries than the primaries. No room at the moment for an insulating spacer. Is there anything that can be done about this situation? 

[cudabob496]

to install a phenolic spacer, and still have room, I used a drop base air filter,
and machined 3/8 of an inch off the top of the intake.  Maybe vent the engine
compartment to get temps down, or ceramic coat the exhaust manifolds/headers.

[Chryco Psycho]

there is a thin alum plate that will reflect the heat , only 1/8" thick that could be installed under the carb like this
http://www.jegs.com/i/OER/691/3969835/10002/-1

[cudabob496]

What's your normal operating temp?
Maybe try to get that down?
I think the water in the heads is about 10 to 15 degrees hotter than the
temp indicated on our meters, which comes off the water pump.

What if you wrap the bowls with aluminum foil, or some kinda heat wrap? Shiney aluminum relfects radiant heat.
Or is there an aluminum like paint that reflects radiat heat?

You could bend some sheet metal, and modify it so it attaches to the bottom bowl screws,
and shileds the bottom of the bowls.

[burdar]

Do you have an extra 5/16" to play with?  They make a 5/16" insulating base gasket.  That's what I'd try.  If that didn't work, I'd try the aluminum plate.

[cudabob496]

Do you have an extra 5/16" to play with?  They make a 5/16" insulating base gasket.  That's what I'd try.  If that didn't work, I'd try the aluminum plate.

Ya, all the heat being conducted from your intake to the carb is probably
the biggest culprit here.

[cudabob496]

at a minimum, double or triple up on the gasket between the carb and intake.

These are supposed to be heat resistant:

http://www.summitracing.com/parts/mrg-54c/overview/

[dodj]

I found if I open the hood as soon as I park it, it doesn't heat the carb up enough to boil out any fuel

[cudabob496]

I found if I open the hood as soon as I park it, it doesn't heat the carb up enough to boil out any fuel

I have an electric radiator fan, with an on/off switch. I can leave it on for a while after
shutting off engine.

[dodj]

I have an electric radiator fan, with an on/off switch. I can leave it on for a while after
shutting off engine.

That's a benefit of an electric fan I never considered.

[burdar]

What air cleaner is on it? An electric fuel pump is helpful in these situations too. You can refill the carb before cranking.

[dodj]

An electric fuel pump is helpful in these situations too. You can refill the carb before cranking.

Ya I agree, I used to have an electric fuel pump but I found the whine to be a bit too annoying. So I went back to mechanical.

[Chryco Psycho]

AN electric water pump has the same benefit you can cool the engine without running it .
 opening the hood will give the heat somewhere to go as well , are you hood scoops open at least ?

[cudabob496]

AN electric water pump has the same benefit you can cool the engine without running it .
 opening the hood will give the heat somewhere to go as well , are you hood scoops open at least ?

Good point about the electric pump, but they seem
to be inadequate in a lot of circumstances, compared
to a mechanical, in keep the engine cool when running.