Carburetor heat soak or vapor lock?

coronet_bob · Thursday at 8:08 AM

I read a post here talking about running a return line to solve a fuel starvation/hard start problem when the car has hot and sat for a brief time. No mention of general driving problems. I was told that this is carburetor heat soak to be solved with a carb parobolic spacer and that vapor lock messes with the car just operating right. Can anyone share their experiences and solutions.
My car has an air gap intake for air circulation but is hard starting when hot and it sits for a brief time. Otherwise it runs great. I have no hood clearance for a parobolic spacer. Thanks

snake · Thursday at 8:22 AM

i had just what your going threw, i could see fuel bubbling,i have the clear window on my holley.Went away after installing 1/2 inch parobolic,you shure not enuff hood clearence.

DeltaV · Thursday at 9:03 AM

I've heard of phenolic spacers and I've heard of polymer spacers, but I've never heard of parobolic spacers, nor have I heard of parabolic spacers.

Does anyone have a link for a parobolic spacer?

R/T Boy 67 · Thursday at 9:48 AM

phenolic spacers.

dfrazz · Thursday at 10:01 AM

I installed a couple of things that worked great for this issue. Cool Carb (- Home) is a great spacer because it is wider so it protects the bowls from heat and its super thin (.155) so it will fit even when hood clearance is tight. I also install a fuel filter with dual outlets with one outlet routing a line back to the tank.

68BabyBlue · Thursday at 10:42 AM

I used to have this problem with the slant six Valiants I drove back in the day, was surprised when it didn't happen with the 1970 GTX I bought in 1977. The factory vapor separator with return line in the second generation GTXs and R/Ts worked effectively. Years later, I owned two GTXs, both of which had been restored, and didn't have the vapor separator installed. I had hot start problems with both. Replacing the factory system solved the problem.

Baby Blue had the factory vapor separator, return line, a carb spacer, and a Holley electric fuel pump from the 70s. That car started like it had modern day fuel injection, under all conditions.

coronet_bob · Thursday at 12:22 PM

snake said:
i had just what your going threw, i could see fuel bubbling,i have the clear window on my holley.Went away after installing 1/2 inch parobolic,you shure not enuff hood clearence.

coronet_bob · Thursday at 12:23 PM

My air cleaner lid is already making an imprint on the under hood insulation pad.

coronet_bob · Thursday at 12:27 PM

dfrazz said:
I installed a couple of things that worked great for this issue. Cool Carb (- Home) is a great spacer because it is wider so it protects the bowls from heat and its super thin (.155) so it will fit even when hood clearance is tight. I also install a fuel filter with dual outlets with one outlet routing a line back to the tank.

Do you think the spacer or return line made the biggest difference?

dfrazz · Thursday at 1:53 PM

coronet_bob said:
Do you think the spacer or return line made the biggest difference?

Return line first because I've ran one without the spacer and it helped. Also, make sure your tank in vented.

ckessel · Thursday at 10:17 PM

At the speed shop I used to work at back in the 80's, we sold quite a few of these shields. They were oe GM at the time. Works for any standard flange carb like Holley's, Carters etc. They used to make another version that was for spread bore carbs, q-jet/tq's etc. These units are very effective for dissipating heat and are thin. One gasket, the shield, then one more gasket. You may need to trim in areas to get around stuff since you're crossbreeding. They were especially effective on RV's.

WileE · Thursday at 11:12 PM

DeltaV said:
I've heard of phenolic spacers and I've heard of polymer spacers, but I've never heard of parobolic spacers, nor have I heard of parabolic spacers.

Does anyone have a link for a parobolic spacer?

this is a parabolic curve.

ckessel · Friday at 10:01 AM

coronet_bob said:
I read a post here talking about running a return line to solve a fuel starvation/hard start problem when the car has hot and sat for a brief time. No mention of general driving problems. I was told that this is carburetor heat soak to be solved with a carb parobolic spacer and that vapor lock messes with the car just operating right. Can anyone share their experiences and solutions.
My car has an air gap intake for air circulation but is hard starting when hot and it sits for a brief time. Otherwise it runs great. I have no hood clearance for a parobolic spacer. Thanks

Bob, what are you working on? What's your engine, intake, carb, filter combo?

Carburetor heat soak or vapor lock?

coronet_bob

Member

snake

Well-Known Member

DeltaV

Endeavor to persevere.

R/T Boy 67

FBBO Gold Member

dfrazz

Well-Known Member

68BabyBlue

FBBO Gold Member

coronet_bob

Member

coronet_bob

Member

coronet_bob

Member

dfrazz

Well-Known Member

ckessel

Well-Known Member

WileE

FBBO Gold Member

ckessel

Well-Known Member

Similar threads