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I have a 1969 435 HP 427 big block and I recently put cam that works to 7200 rpm.
My original intake manifold gets best operation at 5800. Should I change to a different intake manifold to get more out of my engine? My original intake part number is 3933163. Any help with this is appreciated.
 

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I have a 1969 435 HP 427 big block and I recently put cam that works to 7200 rpm.
My original intake manifold gets best operation at 5800. Should I change to a different intake manifold to get more out of my engine? My original intake part number is 3933163. Any help with this is appreciated.
Between idle and 6000 rpm's, a dual-plane, high-rise intake manifold such as the Edelbrock Performer RPM will make more hp and torque than any other manifold you could bolt on the motor. Over 6000, a single-plane intake will make more hp and torque.

Do not make the mistake of discounting the area under curve of the dual-plane at lower rpm's. If the dual-plane makes more power from idle to 6000, there is insufficient time for the single-plane to make up the difference between 6000 and redline.
 

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The manifold you have is a good one, modern Performer RPM and Weiand Stealth are based on it and the Stealth is the exact same height as the GM. I don't kmow the height of the Performer RPM.

The GM intake is said to be good to 575 hp or so and 6500 rpm on a 454, and 6800 rpm on a 427, so not much to be gained from a newer aftermarket dual plane intake.

Same intake was used on the 375 hp 396(L-78) and 450 hp 454(LS-6).

The only place a bigger single plane will help you is if this is going for power above 4000 rpm and going up and not worried about low end torque, then I'd say a Victor 454 would be a good intake. It is going to be taller, if hood clearance is a concern.
 

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GM really got the intake manifold right in the those days. You'd probably find more power in going to rollerized rockers and optimizing the valvetrain geometry that Big Blocks have always struggled with. Problem is, that'll probably be more than the aftermarket manifold you're curious about. Are you still using points ignition? If so, maybe consider replacing that with a Pertronix type kit. This might be able to be done without pulling the distributor at all. This won't make the engine a power house, but it will make it more consistent, not to mention quality points and condensers are getting harder to find.
 

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The 1968-1969 396 L78, 427 L72 and L89 Chevy, 3933163 rectangular port intake manifolds are sought after by restorers and a new one can sell for as much as $500 or as much as a concours 1968-1969 Corvette owner is willing to pay.

BB Chevy 3933163 manifolds with a Winters "snowflake" foundry mark are being reproduced by aftermarket suppliers but they do not have a date code. The reason for that is because placing a date code on a reproduction part authorized by GM would be considered fraud (counterfeit) if it increases the value for the part.

The 3933163 manifolds used on GM crate engines in the 1980s were cast at the Zeus Aluminum Products foundry with no foundry mark. A Winters Foundry "snowflake" or Central Foundry Division "wagon wheel" foundry mark will be on GM production manifolds.
 
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