The "THEORY" behind the manifold is good but it does ASSUME that air flow will flow through the air gap resulting in lower fuel temperatures (cooler intake charge).
Does this really HAPPEN in a real life situation. IMO, NO. If you don't have a manifold, I would certainly get a AIR GAP but if you already have a Performer RPM manifold (non-air gap), I woiuldn't spend the money.
Yeah, I have a few buddies at work whom are mopar fanatics, (hehe!!!!! we'll forgive them) no but seriously, These guys swear by this intake. My friend has a 340 he's putting in a 70 dart swinger and he just ordered an air gap. I was wondering why they only offered it in a square bore? I have a 406 with a spread bore and a 600 holley single feed but the engine for some reason doesn't want to turn up much harder than 4800 to 5000 rpm. I was wondering if the air gap would help me out with this problem and maybe bump the 600 up to a 650 or 750 double pumper?
I would look towards the carb rather than the manifold. Most 600 single feed Holley's (i.e.1850's)are not really performance carbs. They are good for stock motors, but not much else. I would look into a different carb, something like a 750 vac. Holley. Also what manifold is on your car now?
It's supposed to be. IMHO add an insulator gasket under the carb and you ready to go. It should keep the manifold temp down a little. Edelbrock has heat insulator gaskets for abotu $15. single or dual plane intake.
I would agree though don't go out and buy an intake just cause it's new. You can accomplish basically the same thing with an insulator under your carb and keep your fuel line as far away from heat as you can.
They also make oil shields to go under the intake so oil doesn't hit the intake bottom and help to heat it up. But if your running the exhaust crossover passage your wasting your time trying to insulate the carb.
Thanks for the replies guys! I have a edelbrock performer spreadbore on the 406 now. The valley baffle under the intake manifold seems like a good idea also. I think at this time my 600 single feed holley is the hold back for the performance I want!!!!!!!