QUOTE(SirAndy @ Apr 10 2009, 02:47 PM)
QUOTE(maf914 @ Apr 10 2009, 12:20 PM)
let the manifolds heat up to promote fuel atomization?
Sounds good in theory, but that's not how it works. Carbs suck huge amounts of air through a small opening, thus dissipating a lot of heat.
Ever heard of carbs "icing" up?
Go for a spirited run and immediately get out and touch your carbs. They'll be very cold. The same principle is used in refrigerators to cool down the air inside.
What the thick FI gaskets do is help preventing
heat soak when the car idles or after you shut it off.
A hot motor will heat up the manifolds and carbs after shutoff and can boil the gas in the float bowls. The carb version of "vapor lock".
While you're running the car hard, they make no difference. But they insulate the runners from the heads, minimizing heat transfer at idle or after a run.
Andy
What if a guy was to lose the spacer between the intake and head and place one between the carb and the intake? It would probably have to be a thicker one but it would still do the job of preventing the gas from boiling in the carb, which would then, theoretically, allow the gas to atomize in the manifold, right?
I only ask because this is how the carbs are mounted on some older American cars and pickups. The intakes are bolted directly to the heads and then a thick (some as thick as 1/2") spacer/gasket is placed between the intake and carb. I don't know if engineers back then
planned to atomize the gas in the intake, but the spacer was there to prevent the carbs from overheating after shut off and causing vapor lock.