The V8 Owners Forum -

Hello, does anyone know what sort of clearance I should have between pistons and valves. I'm using a crower 50232 cam in a 4 litre. I have contact and need the pistons pocketing.

I seem to remember that I needed around 70 thou clearance. But I'm probably wrong as usual???

it's the exhaust that's important as it's opening when the piston is on the upstroke. I agree with the above, you need .060" or thereabouts.

Just to add another vote for 60 thou minimum.
Mike

Boosted LS1 wrote:it's the exhaust that's important as it's opening when the piston is on the upstroke. I agree with the above, you need .060" or thereabouts.

Exhaust will begin to open on the downstroke, before BDC and close a short time after TDC.

The intake will be opening just before the piston reaches TDC, and since the intake valve is larger, it might need larger cutouts too.

Jeff