gas fumes

It is important to insulate the carb from the intake manifold as much as you can.
Right after you shut off a hot engine the temperature actually rises under the carb and tends to boil the fuel out of the carb.

This makes the fumes rise out of the carb vents.
Depending on the air cleaner, this is when you smell it the most.

thx PD - this sounds plausible - how do you "insulate" the carb from the intake/engine?? - thx, stephen

Stephen,

A phelonic spacer under the carb will help isolate the it from the heat of the intake. That's what it's made for. You could also use a heat shield under the carb, I think Holley used to make one. You could try Summit Racing at 800-230-3030 for these items.

Michael

Thank you Michael.

Here are some offerings from summit...?

http://store.summitracing.com/egnsearch.asp?N=700+4294814811+115+4294865529

phenolic...?

http://www.cantonracingproducts.com/phenolic/spacers.html

I would check and make sure the bottom of the gas tank isn't wet. Panteras have a bad habit of rusting out the bottom of the tank right where it sits on a bracket.
While you got your head under there, take a look in the area of the fuel pump too.

thx rd!

quote:

Right after you shut off a hot engine the temperature actually rises under the carb and tends to boil the fuel out of the carb.

Sure, that could be the cause. But...

I have no spacer for my carb and have never had any gas vapor smell problems. Car is parked, usually with rear deck still closed, in a garage, and I've never come back out to the smell of gasoline.

If I started smelling fumes, I wouldn't go out and buy a spacer, but instead I'd start looking for something leaking from somewhere.

Larry

Your welcome, edl.

Your links are right on. They are the products I was thinking of. Here is a quote from the bottom link:

What is Phenolic?

Phenolic is a material used in the Aerospace and Electronic industry for its superior insulation properties. It has even been used by NASA during the space exploration as a heat barrier. Phenolic is made by compressing layers of resin soaked canvas while under heat. When cured, it has a brown grainy appearance which is commonly mistaken as “wood”.


Why we use it

We use Phenolic in our carb spacers and adapters to stop the transfer of heat from the engine to the fuel system. Intake manifolds and aluminum carb spacers readily transfer heat through the carburetor heating your fuel which has an adverse effect on performance. Our Phenolic spacers and adapters stops this transfer, therefor lowering the fuel temperature.

End quote.


The aluminum heat sheilding would divert the heat that rises off of the engine further away from the carb.

Although these are great mods that will help free up some lost horsepower, they may not solve your problem. You shouldn't smell gas when you turn the engine off period. You could also have an old hose that has cracked and is leaking. A friend of mine lost a BMW because of that. The hose leaked fuel onto the hot intake manifold, and it ignited setting the car on fire. He said it happened so quickly that he was lucky to get out without getting burned!

I'm not looking to scare you, but the worst case scenario is always a possibility!

In any event, the heat shield and phelonic spacer ARE beneficial.

Michael

One other point to look at. I have had cars where I could smell gas but never did find he culprit until its nasty head showed itself. That being the mech fuel pump. If the diaphram decides to crack it can let enough fuel into the pump housing but not enough to really show the leak, then once the diaphram lets go it could go out the pumps vent or worse case be dumping fuel straight into your crankcase. Just something else to look at.
Jeff

Many thanks guys!