Gm 455 intake manifolds

[Bonnewagon]

The factory stock Pontiac 4 barrel manifold is all you need for a street car. Testing showed it to be superior to many aftermarket manifolds. Even the highly touted and rare RAM AIR aluminum manifolds weren't all that much better for the street. As stated, the Edelbrock Performer is just an aluminum copy of the factory unit. You can save some weight but a Pontiac V-8 is a very heavy engine to begin with. What year? The early heads would have the large exhaust valves VS the slightly smaller valves used in EGR engines. The EGR manifolds are looked down upon but, again, testing showed there to be very little air flow penalty. A 455 in a G-body is probably all the power you could ever want or need. As a long stroke engine it makes power way down low so do not make the mistake of using a high rpm manifold. Spend your money on something else.

 

[Merlin1952]

Afellowcarperson; Without knowing what year your engine, or more importantly your heads are, the best factory 4-barrel intake to get is for the 1972 Pontiac V-8 engine ( part number 485912 ). In 1972 there was a change in the passageway for the heat crossover and can be a mismatch if a pre-1972 intake is used on the later heads and the same holds true when using the later intake on the pre-1972 heads, The 1972 will fit either heads. A Edelbrock Performer would be just a light weight copy of the factory intake. The Performer RPM is a nice upgrade in performance as well as being lighter in weight for a streetcar. Like someone else mentioned the Performer RPM is about 1.25 inch taller than a Performer or stock intake but that 80 Bonneville should have clearance. You can always loosely wad a piece of aluminum foil and lay it on top of your air cleaner then close the hood. Open the hood and measure the thickness of the aluminum foil and that will tell you how much clearance you have available, Hope this helps,

 

[Bonnewagon]

Please read this one- http://silverstatepontiacs.com/jharticles/jharticles14.html and then this one- http://silverstatepontiacs.com/jharticles/jharticles9.html I don't think the '72 manifold is the answer but I could be wrong. The change to EGR created the mismatch and the pushrod cover needs to be the same too. H-O racing used to sell the stainless steel plate that made the gasket conversion work perfectly. I have had to do his many times and resorted to making my own plate to use the early intakes on later engines.

 

[Merlin1952]

It’s been a very long time since I studied up on the nuances between the pre-EGR and EGR Pontiac intakes but I do believe I am correct on what I wrote before. However, as was mentioned the EGR (1973 and up) intake manifolds do require a 1973 and up valley pan. The pre-73 intakes will work with the later valley pan but the EGR intake has to have a valley pan with recessed area in the middle to accommodate the extra mass under the heat crossover of the intake.

 

[Bonnewagon]

a very long time since I studied up on the nuances between the pre-EGR and EGR Pontiac intakes

Copy that. Me too. And I have a set of 1972 455 heads and the intake so I "should" know. I should really check that out because I also have a 1976 455 that has EGR and I'd rather do without that.