PAmotorman

grind a very shallow groove like shown in the pictures to vent the rubber pump check valve area back into the float bowl thru the hole that is already there. just grind deep enough to vent and shallow enough the rubber valve will seal when the pump is activated.

DansYellow66

Right now I'm fabricating an aluminum baffle to mount between the primary float bow//accelerator pump and the intake to try and cure heat soak of the accelerator pump circuit. I'm pretty far along on it so I'll give it a try. But if it doesn't work, I'll try your idea.

Thanks

MikeM

That is a good trick to fix it like that the right way but I've read here where one guy cut some spacers out of plywood and stuck them under the carburetor and called it good.

Don't know what would happen if that gas soaked plywood got exposed to a backfire!

tbarb

One other thing is to drill approx. .015-.018 hole in the floor of the bowl to relieve the vapor pressure.

PAmotorman

there is a very small hole in the floor of the bowl and that is were the groove goes to vent the area under the red rubber diaphram that causes a pumping action

PAmotorman

that is a old drag racers trick to insulate the carb from the engine heat. you have to keep tightening the carb mounting nuts because the plywood keeps compressing.

DansYellow66

I built a shield for the dual Holleys on my ERA Cobra to shield the accelerator pump cover from radiant heat off of the intake. Not enough room to fit the Mr. Gasket type shields.







While it helped, unfortunately it was not an complete success. Still getting a couple drops of fuel out of the accelerator pump squirter in the rear carb about 10 to 15 minutes after I shut off the motor. Stinks up my garage for a day or more but doesn't cause any drivability or starting problems.

So - you don't think creating that small backfeed path is enough to upset the calibration of the accelerator pump action? Some fuel has to bleed back to the fuel bowl when the pump lever is activated - but maybe it's too small to matter.

PAmotorman

the soft rubber of the check valve should seal the groove when the pump pressure is applied. does your engine have a exhaust heat passage thru the intake manifold like a chevy then I would block that crossover with some stainless steel shim stock to take the exhaust heat out of the intake manifold

MikeM

I have read here on this forum that a little piece of scrap metal is not to be trusted for this job. This came from the foremost authority here on blocking exhaust crossovers and construction grade plywood carb spacers.

PAmotorman

you must use stainless steel to take the heat and exhaust pressure. I used .005/.007 thick stainless steel shim stock and never had a burn thru.

MikeM

Nope, I was advised here not to trust that.

Something was said about paying $39.95 for a real professional set that had that shim part of the gasket set.

There is a lot of good info available here. Some is useless. I like your idea.

PAmotorman

I did dozens of engines and I never even removed it the intake. I just drained down the rad and loosened all the intake bolts and slid the shims in between the manifold and the heads

MikeM

Danger, Will Robinson. Danger.

I was also told here this won't work either.

Maybe somebody ought to check it out and report back. Save $39.95.

DansYellow66

OK - I see the idea now. It has an exhaust passage but I'm pretty sure the builder blocked it off.

Scott Marzahl

Clem and Tim,
Since a 3810 does not have the rubber check valve, it uses a ball bearing, would a .015" hole back into the bowl serve the same purpose?

PAmotorman

yes my post only applies to the carb with the red rubber check valve not the one with the ball bearing check valve.

Scott Marzahl

Just so that I am clear on your reply Clem, drilling a small hole would work with the ball check valve style?

PAmotorman

the hole should already be drilled from holley in the float bowl.

PAmotorman

drill a .015 hole clear thru hole #1 in the metering block. this will vent the squirter passage into the float bowl and relieve the pressure.

MelWff

That hole feeds the passage in the main body going to the squirters. Drilling a hole straight through means the gas will go into the float bowl not the squirters when the car is running and you step on the gas pedal.