Holley hot stop fuel perc issue

[carmine]

Hello Dan.

Get rid of the composite gasket and replace with layered aluminum heat shield kit from Mr gasket.
I have tried same as you with composite gasket and aluminum shielding of bowls with minimal results.
The Mr gasket shielding eliminated the problem completely.

Heres the link; Mr. Gasket 3712, Mr. Gasket Carburetor Heat Shield | Mr. Gasket

[DanEC]

Originally Posted by carmine

Hello Dan.

Get rid of the composite gasket and replace with layered aluminum heat shield kit from Mr gasket.
I have tried same as you with composite gasket and aluminum shielding of bowls with minimal results.
The Mr gasket shielding eliminated the problem completely.

Heres the link; Mr. Gasket 3712, Mr. Gasket Carburetor Heat Shield | Mr. Gasket

Do you know how tall the gasket stack is? I only have room for a hair over 1/4 inch thick base gasket because I have a smooth hood. I considered the Mr. Gasket heat shield set up but with dual carbs and all the accelerator linkage and rear mounted breather I thought I would end up cutting the shields up into pieces.

Gaz64 - I haven't looked but I suspect it has the rubber umbrella seal in the accelerator pumps. On another forum someone suggested taking a dremel and grinding a very shallow grove from outside the umbrella to the relief hole under it. The theory was that it would allow vapor pressure to vent back to the fuel bowl and bowl vent but would seal off when the accelerator pump was activated.

I haven't had a chance to look yet but I wonder if Holley makes a composite accelerator pump cover that doesn't absorb heat so easily?

[carmine]

Stack approx 3/8 inch high.
I had hood clearance issues as well so i eliminated 1 gasket and 1 of small aluminum shield which brought total stack down to approx 1/4 inch.
The larger shield can be notched out in order to clear any linkage obstacles.
In your case you would be using 2 kits because of dual carbs then trim excess on large shield that overlaps between carbs.

[DanEC]

Carnine - thanks, I will probably order a couple and try them.

[Gaz64]

Originally Posted by DanEC

Gaz64 - I haven't looked but I suspect it has the rubber umbrella seal in the accelerator pumps. On another forum someone suggested taking a dremel and grinding a very shallow grove from outside the umbrella to the relief hole under it. The theory was that it would allow vapor pressure to vent back to the fuel bowl and bowl vent but would seal off when the accelerator pump was activated.

I haven't had a chance to look yet but I wonder if Holley makes a composite accelerator pump cover that doesn't absorb heat so easily?

Yes, that would work BUT extremely risky, way more accurate to drill a hole.

The place for the bleed orifice is already there just not drilled through.

.013 from memory, number 80 drill.

Gary

[Randy Rosenberg]

Originally Posted by Gaz64

Yes, that would work BUT extremely risky, way more accurate to drill a hole.

The place for the bleed orifice is already there just not drilled through.

.013 from memory, number 80 drill.

Gary

Do you have a picture or diagram/drawing of where this bleed orifice is located? I would hate to drill a hole in the wrong place...

Thanks,
Randy...

[DanEC]

Originally Posted by Randy Rosenberg

Do you have a picture or diagram/drawing of where this bleed orifice is located? I would hate to drill a hole in the wrong place...

Thanks,
Randy...

This thread from Corvette Forum discusses grinding a shallow groove to relieve pressure - but it shows the bleed orfice.
http://www.corvetteforum.com/forums/...shut-down.html

[Gaz64]

Here's the pic I posted in post 9.

http://www.bob2000.com/acccheck.jpg

Do you see the blind hole at 11 o'clock in the right hand bowl?

That's where the pump chamber vent used to be, but obviously Holley isn't doing it anymore.

The rubbish on the other forum would do nothing if the hole is there as he claims.

Both of the holes under the umbrella are inlets to the pump chamber.

Cutting a groove joining a .013 hole to a .100 hole just going to reduce pump shot further than what you already have since more will bleed back to bowl.

The size of the bleed is a balancing act. No bleed gives full pump shot but no venting. I probably wouldn't exceed .020.

[DanEC]

For what ever reason he apparently decided to grind a groove back to the feed hole under the umbrella seal - instead of drilling out the auxiliary vent hole. Not sure I buy into that either. Prefer to get the temperature of the accelerator pump cover down a few degrees in hopes of keeping fuel in it below it's vapor level. It may only take lowering it a few degrees to make a difference.