As stated in my other thread I am considering Changing from a single plane intake to a Dual plane on my 427 SBC, Does any on know if a RPM air gap ports will match up to my dart pro 1 215cc heads? I am concerned with the top height of the rpm manifold having enough material to port match to felpro 1206 gasket.

man with those cubes an rpm will kill it above 4500rpm
so the port match will be the least of your problems as it may cost you 5hp, and the intake itself waaay more.

I can only speak from BBC experience. They match pretty close, I port matched mine to my heads only needed minor amount of matching.

i went from a vic jr intake to an rpm air gap,and i also have dart pro 1 only 200cc sbc 355.My mph was 113 with the vic jr its now 116mph.Thats really the only diff it made with my setup i was actually hoping it picked up my 60' times,but so far it has not.

man with those cubes an rpm will kill it above 4500rpm
so the port match will be the least of your problems as it may cost you 5hp, and the intake itself waaay more.


I agree 100%

I have 215 iron Eagles on a 408 and they were sized right but were off a tad on alignment - had to set the intake on pushed all the way against the bolts to line them up closer, not perfect but closer. I would imagine there's a bit of deviation from one to another so can't say all would be off - plus you are using Pro 1s not iron eagles so they could be all together different.

I used a 1206 gasket and it looked like there's enough to port match the intake if I recall correctly, but I personally didn't think it was worth messing with.

I agree 100%
x3

man with those cubes an rpm will kill it above 4500rpm
so the port match will be the least of your problems as it may cost you 5hp, and the intake itself waaay more.

Is that a specific issue to a SBC RPM intake?

I can only speak from experience on my 10:1 383 combo and it went .05 quicker in the 1/8th and .03 quicker in 60 foot with an RPM vs. a Vic Jr. shifting at 6500. I know a bigger cube SBC is an entirely different animal. Dual planes work great on street/strip and some strip only BBC's but the port volume is larger.

man with those cubes an rpm will kill it above 4500rpm
so the port match will be the least of your problems as it may cost you 5hp, and the intake itself waaay more.My 408 peaked at 5100rpms and Im pretty sure it's the cam (XR276HR from Comp Cams) that stopped it from going higher not the RPM air gap. Torque peaked at 4100rpms.

This is from "How to Build Big Inch Chevy Small Blocks". It references the RPM Air Gap versus the Super Victor. Don't know how the Victor Jr. compares though and what comes into play with all those extra cubes.

http://www.cartechbooks.com/vstore/showdetl.cfm?st=0&st2=0&st3=0&CATID=21&Product_ID=3166&DID=6&chapter=6732
"We’ve even seen dyno comparisons pitting the RPM Air Gap against the much-vaunted Edelbrock Super Victor single plane. In this test, the 383ci small-block was fitted with an excellent set of Dart Pro1 CNC heads and making over 500 hp. The 2925 Super Victor made the most peak power, but the Performer RPM Air Gap generated significantly more torque throughout most of the power curve. With a typical street car with a limited gear ratio of 3.55 or lower gears, this combination would be quicker in the quarter, especially with a heavier car that needs torque to help it accelerate. The 2925 manifold would be best in a lighter car with a 4 or 5-speed and deeper gears that could take advantage of the upper-end horsepower created by the single plane.

This is not always the case. For larger displacement small blocks, like those above 420 cubic inches, for example, would usually benefit from a good single-plane intake. While shorter runners reduce lower-end torque, in the case of a 427 to 454ci small block, these engines make so much torque anyway that you can afford to sacrifice some low-end torque in order to make more top-end power. The key would be to choose a high-flow intake with relatively long runners. Here is where an electronic fuel injection intake could be of benefit since this may open up intake runner options."

Would the single plane benifit from a carb spacer or some where I saw a anti reversion spacer? If it peaked at 550hp@6300 and 518tq@5900 with the single plane, What could I expect with the dual plane and it is realy how would a dual plane effect the 1500 to 2000 rpm range jerking that I am getting in 1st and 2nd gear under light engine load. Also as stated I am running a alluminum flywheel and considering going to the steel one that I have to help this condition also.

Is that a specific issue to a SBC RPM intake?

I can only speak from experience on my 10:1 383 combo and it went .05 quicker in the 1/8th and .03 quicker in 60 foot with an RPM vs. a Vic Jr. shifting at 6500. I know a bigger cube SBC is an entirely different animal. Dual planes work great on street/strip and some strip only BBC's but the port volume is larger.
Not at all (my 383 ran 10.70s with an rpm)
Its the cubes, theyre gonna need some air at rpm, and the cross section isnt there with an rpm, even a super victor is gettin on the small side at 2.8" sq. for a 427