Quote:
Originally Posted by steve25
If your rebuilding a RA4 do use RA4 type tulip Intake valves as they really don't flow any better under dynamic conditions and only add weight to the valve train. If you don't belive me then ask yourself why Pontiac did not use a tulip type Intake in the 455SD, or why the aftermarket heads don't use them!
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Pontiac did use a tulip intake valve in the SD 455 engines. Visually it's almost identical to the RAIV valve but has a 45° valve face and it's shorter.