# Performer rpm air gap on a 400



## SPCMarty (Jul 29, 2011)

I guess the idea is that the air gap keeps a cooler intake temp. Any one install one before? I'm wondering if it's any better than the regular performer rpm, and if the fact the coolant passage is blocked is an issue with 400 overheating. 


B. Co. 1-22 Infantry 4th Infantry Division OIF 2008-09


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## BearGFR (Aug 25, 2008)

All Pontiac intake manifolds are already "air gap" manifolds, even the factory cast iron ones.

Bear


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## SPCMarty (Jul 29, 2011)

Well the ones I'm looking at are specifically called air gap, and omit the center coolant passage. 

http://www.ebay.com/itm/380371501773?redirect=mobile


B. Co. 1-22 Infantry 4th Infantry Division OIF 2008-09


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## BearGFR (Aug 25, 2008)

Ummm... NO Pontiac manifolds have a "center" coolant passage. The only coolant passage is the crossover that's on the front of the manifold and goes between the two cylinder heads. The only 'center' passage is an exhaust crossover. It provides exhaust heat to warm the manifold under the carb plenum ot help prevent puddling fuel and aid in fuel vaporization, especially in code weather. Yes, you can block that heat passage off and get a little cooler, denser fuel mixture into the engine but you will pay a price for it in terms of making the engine a little more "cold natured". Some aftermarket heads, like the Edelbrock round ports, don't have those passages in them at all.

I looked at the Ebay ad, and that manifold indeed omits the heat crossover under the plenum and blocks off the passages. It's not a bad looking manifold, actually, and being a dual plane it -should- have decent low rpm manners. Still, the "air gap" claim is just fluff - EVERY Pontiac manifold is an "air gap" manifold. This is just a case of some marketing genius borrowing the term because they know it's a popular buzz-word, especially with the bow tie brigade. 

It's not a bad looking manifold, but it's possible to take a factory cast iron manifold (which is also dual plane) and remove the heat crossover, block the passages, and modify the plenum divider so that it's a carbon copy of this one - the only difference being that it will be heavier because it's cast iron and not aluminum - but you can get it for the cost of some cutting tools and investment of your time instead of spending $179.

Bear


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## jetstang (Nov 5, 2008)

I like it. Says it' 1 1/4 higher than stock. Don't know how much higher the performer is. It would be cool in the south, but like Bear said, not great for a street car that wants some heat.


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## leeklm (Mar 11, 2012)

jetstang said:


> I like it. Says it' 1 1/4 higher than stock. Don't know how much higher the performer is. It would be cool in the south, but like Bear said, not great for a street car that wants some heat.


I forget what car you have Marty, but be aware of hood clearance... I know my 66 is VERY tight on hood clearance with the factory manifold and 2" air cleaner...


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## ALKYGTO (Mar 29, 2010)

Not sure of your engine combo Marty, but don't get a case of the "BIGS", too much intake, cam, carb can make for a sluggish combo if you don't have the compression, gears, etc. to take advantage of it. Pontiacs make great torque with "stockish" parts and the intake is one of the best cast iron intakes ever installed on a production engine. The only dissadvantage they have is wieght, they are heavy. NPD offers an aluminum one - MANIFOLD INTAKE ALUMINUM | C-3265-218A | NPD - but it's $399. A performer or one of the older used aluminum dual planes may be better for you.


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## SPCMarty (Jul 29, 2011)

I had no idea that was an exhaust crossover, I assumed coolant. 
I already have a performer with a 1" riser, I was just rather curious about this one labeled as air gap intake. 

I have a rather mild build I'd say.557 code 400cui .030 over, with 142 heads milled to create 9.3cr and a lunati voodoo "torque monster" cam. Forged pistons too. 
I have yet to fire up this engine however. 


B. Co. 1-22 Infantry 4th Infantry Division OIF 2008-09


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