Rpm vs Airgap

[funsummer]

Ok,
Rpm FE manifold port matched vs Rpm air gap intake with jays adaptor.
Am I splitting hairs or is there a gain to be had?
Have read Barry’s and Jays books and jays post on his adaptor, the answer is not clear.
I am sure other street builders are interested.
390 stroker
444 cubes 238/ 600 lift cam, roller hyd cam from Barry.
Heads flow 360 intake reworked edelbrocks
Pump gas build.
Thanks for a fantastic forum and great members.
Joel

[JamesonRacing]

The RPM, port matched, is a very capable intake manifold. 

Heat transfer in aluminum is very quick.  After an engine has been at operating temperature for more than a few minutes, the intake manifold will be at the same temperature, air gap or not.  Carbs may see some temp reduction with an insulated spacer, but I think the temperature difference in the aluminum intake manifold in negligible on a street car. 

For what you're doing, I'd port-match the RPM and spend my time and effort elsewhere.

[jayb]

I would say there is no significant performance gain to be had by using the adapter and 351C Performer RPM intake, vs. the FE Performer RPM.  The advantages of using the intake adapter would be the ability to easily change to another intake in 15 minutes or so, access the valley of the engine without tearing the whole top end apart, etc.  The intake adapter offers flexibility that you don't get with a stock type FE intake manifold, but between the two Performer RPM manifolds, you won't see much of a performance difference.

Just an FYI, but on the 428CJ in my 68 Mustang (about 440 HP on the dyno) I use the intake adapter.  I started off with the 351C Edelbrock Torker, then switched to the Performer RPM, but have now switched back to the Torker.  Both manifolds spin the tires with impunity, but the Torker feels stronger in the upper RPM range.  It was nice to be able to make that comparison.