cooper9811

I have to agree with gkull, I had a fuel boiling problem with my intake as well - took a heat shield and return line to solve it. I now run a heat shield and return regardless of carb/intake.

AirBusPilot

I hear ya. I too doubt there's much of a difference, I'm just thinking with the engine at speed you get airflow underneath the manifold and it helps cool it..some. Good idea on the wood spacer. I wish I had the space for one..don't think I do.

toddalin

Are you sure that this difference isn't more due to the exhaust crossover present in the Performer RPM rather than the hot oil?

I use the RPM with the crossover blocked off, and I have a lifter valley splash shield. I also have a 1/2" open spacer. All are port matched and the inside of the RPM has been "massaged" and this probably outflows an Air Gap.

When CarCraft ran the RPM and Air Gap manifolds on the same engine, IIRC the difference was about 3 hp at the top end. Block off the heat riser and cut down the plenum (maybe killing a bit of lower end torque) the difference is probably nil.

The RPM and Air Gap are reported to be the same height.

toddalin

If you use the correct GM air cleaner lid and wing nut, there is little chance of this happening. (But you could hit the lid.) The correct GM top cover has a much deeper dish in the center (and is better at turning the air into the carb) and the stud and wing nut can fit entirely within the dished area. Of course the center is a bit higher around the indent.

AirBusPilot

Could be.. I dunno. I have an RPM Air Gap. Sounds like there are 4 versions, Performer and RPM, both having the optional Air Gap.

mikem350

I fought this problem on couple cars w Holleys. Did not have room for a spacer. If am Air Gap helps even a little...next time I try one for sure!

fastbruce

It solved mine on my Nova SS Big Block so when I got the Vette and had the same problem I immediately changed to a RPM Air Gap and it fixed it

Postal123

Don't forget about body mounts when making hood fitment comparisons...aluminum vs rubber/poly and/or condition of rubber/poly. My '68 with new poly body mounts, RPM Air Gap, PJ III (Dominator dimensions) and 3" element on a flat base are about 1.75" above my '68 small block hood lines (have a '67 BB scoop)...so an early small block hood would work with an Air Gap intake if a drop base is used, but I'd say 2" drop base on poly or up to 3" on aluminum or aged body mounts...

Note: the PJ III uses a 1/4" throttle body spacer

MyRed69

'69 with a 383, air gap and Quick Fuel 750, poly mounts. I have only test fitted the stock S/B hood (since the car is not finished yet) I have only about 1/2 inch (maybe) above the carb without an air filter... I picked up a stock small block hood at the Kissimmee NCRS show to play around with and make a testbed hood similar to a Z06 hood and keep it as low profile as possible. So, LONG answer to part two of your question; no, an air gap will not fit under your stock S/B hood (with an air cleaner)

fastbruce

Mine fits just fine with a Air Cleaner

Postal123

So Fastbruce, you've got a '75 small block on rubber or poly body mounts, an RPM Air Gap, 3" air cleaner and no issues...are you using a drop base?

I just want to clarify since the hoods were different among years...

v/r,
Rob

c69vete

It has been a while since I have posted these pics. Maybe they will help out.




Assuming the GM aluminum intake is an aluminum version of the cast iron intake. The air gap shown is the Performer air gap. It is on my car now. The Performer RPM is the tallest and I believe the Performer Air Gap RPM is the same height. ( not shown ) I think the Performer was a copy of the original LT-1 aluminum intake.

fastbruce

Energy poly mounts, RPM Air Gap, Proform 3 inch AC with whatever drop that is, I just had a bunch of teeth pulled this morning so im couch bound for today or I would measure the Air Cleaner drop

Torqued Off

The communication in some threads can drive a guy crazy.....and every word means something. Truth is that Edelbrock makes a Performer intake, a Performer Air Gap intake, a Performer RPM intakes AND a Performer RPM Air Gap. That is FOUR different intakes.

I believe both RPM's, the regular RPM and the Air Gap RPM are advertised at exactly same height. Check the Edelbrock website.

The photos above can fool you, but the highest one is a Performer RPM, the Air Gap shown is a standard Performer Air Gap, NOT a Performer RPM Air Gap.

7t9l82

the R.P.M air gap on my car does take a while to warm up. as far as power difference? i think there is some difference. a lot of people say they notice no difference, normally those are people who don't tune for the new part. you need to optimize your combination for best results.

c69vete

I agree. If you read what I wrote, nowhere does it say that it is anything but a performer. I stated the performer RPM air gap is NOT shown. The Performer air gap is actually 1/8th of an inch taller than the Performer.

7t9l82

bless you for posting these pictures, i have been trying to tell people here that the L-82 intake is different than the performer and the L-82 intake is a generic q jet manifold ether its aluminum or not.

AWilson

ok, based on info from another thread I am going Performer. If I am looking at the pictures correctly it seems that it will be 7/16 inch taller than stock (assuming my stock 68 327 intake is the same height. That has to work because I could get a 1 inch drop if I must.

74 vert

http://www.hotrod.com/how-to/engine/...manifold-test/

Pricey, but the composite seems to be an interesting option. To bad the link didn't run the duel plane intake.