Chris69

Decided to try a 1/2" phenolic 4-hole spacer to see if it would make a big difference in keeping the Holley cool and stop the percolating and gas smell in the garage. It was a lot cooler outside, but after a 45 minute cruise, the carb was cold to the touch. I let it sit for 10-15 minutes and felt it again, since the engine heat would have really saturated things by then. Still cool. Before this, it would get so hot you couldn't touch the carb! Very Kool!!

Got the kit from Summit (Summit brand) for $27 (included the spacer, two gaskets, new studs, nuts & washers).

:party:

Barry's70LT1

They do work great.
I run a 1/4" spacer and it made a huge difference as well.

killervette666

I run a 750 speed demon and noticed that itd get very hot after running for a while, would it work on aluminum castings to? :cheers: :cool:

Gordonm

I have this same problem of fuel boiling out of the carb. I have been waiting for someone with positive results from a spacer. I think I have room for only a 1/4 inch spacer but would like a 1/2. Is it a 4 hole spacer or open plenum spacer

bigvette1

Question - is the exhaust crossover blocked off in the intake manifold? Also, do you have the heat riser in the rt. hand exhaust manifold and does it work? Gas boiling out is a common symptom of the exh crossover open and/or the heat riser partialy shut. Glad the spacer fixed the problem.

Eddie 70

I have been thinking about getting one of the Air Gap manifolds. Wouldn't this take care of this too?

Gordonm

My AFR heads have no crossover in them and I am running headers so I have no exhaust near the intake. The Air gap intakes will help this but they still have the heat from the intake manifold that transfers to the carb, but it is far less due to the intake sitting in the air. Maybe some Air Gap users can answer this better.

Chris69

I have the 4-hole spacer since I didn't want to add any additional plenum volume to the single plane intake.

When searching for one of these, I ran into some phenolic head to manifold insulators. Anybody ever try these?

bigvette1

Can't answer fo the Air gaps but that is maybe why the stock Q-Jet gaskets are 3/8" thick.

Barry's70LT1

They are inexpensive and should work on any carb.
I don't remember if it is a 4 hole or open. It's been on there for about 10 years.
I also run headers, and have the exh. cross over partially blocked. (Restricted).
Also a picture of the spacer installed.

gkull

Eddie 70

IMO - The air gap is a marketing scheme. It basic physics. Some materials have rapid heat X-fer. Iron, copper, aluminum. that's why they used for cooking. You heat an area of the metal and it all nearly reaches a consistant temp.

I have run tall single planes for years with the "air gap"

Just playing around on a running motor and using a IR point and readout the thermal surface temp and the intake right under the carb of my running motor was within 10 degrees of where it attached to the head. I would atribute the temp difference more to the vaporizing gas than the colder air flow accounting for the temp difference. Aluminum is a very good heat conductor. So :bs

I had gas boiling many years ago an went with an open 1/2 wood carb thermal spacer. They do work better as a thermal barrier than Phenolic.



[Modified by gkull, 12:45 PM 11/24/2003]

adamdinat

This sounds like exactly what I need. The gas smell after driving makes me nervous. I usually leave the car outside for awhile or leave the door open.

Chris69

:smash:

Well... the weather has warmed up around here the last couple days and guess what.... The insulator is no longer doing its thing.... Guess I jumped the gun thinking it would cure the percolation problem, but the cold weather tricked me. The carb is still cool when I first shut it down, but after about 30 minutes it's once again very hot to the touch. And, of course, the gas odors are back. The insulator itself is also hot as hell! $27 bucks down the drain?

Maybe I'll try one of those big ugly heat shields to see if that helps keep the heat off the carb. Anyone tried those things?

comp

only to use as a base to seal to hood scoop, i need to make sure i'm on the
same page as others, PHENOLIC is the hard plastic spacers (yes/no) i think of
plywood being in the composite group the plastic spacers helped me ,but the wood seamed to do better, maybe need both, ?????

comp

forgot to add (dah) i insulate fuel line to...

427V8

I have a 1/2 inch wood spacer that has completely solved my perculating carb. I have a RPM Air gap.

It used to be so bad you could hear the gas boiling after shutting the car down.

Now the carb stays cool and it never percolates!

Wood rocks

comp

glad to hear, i haven't used a new Edelbrock air-gap yet, plan on a build for
truck (to tow trailer) 383,vortec's with pocket work, air-gap perf. , small hyd.
roller, Q-jet, high 3 to low 4 rear gear , and 200r4 trans.

Chris69

Phenolic is some kind of resin-coated layered material, not a solid plastic. Looks kinda like wood though. Obviously doesn't insulate as well as wood. Lars left a great response in another thread about using a carb shield to deflect heat from the accelerator pumps.

Hey... if you use two wooden spacers, would it sound like a motor? Wooden - Wooden... :lolg: :lolg: :lolg:

comp

good one, hope not like a saw, got other one from lars, he probably has forgot more than i know,. is there a way to hunt for just 1 subject in the forums??? thanks.