jt76

iTrader: (10)

Just as the title says, when checking for PTV what is the minimum amount of clearance required? Using the clay method, the valves didn't bust through the clay, but the intake valve looked rather close.

Thanks.

KevinR

I never used the clay method, but 80 thousandths is normally pretty ideal for clearance

z28241

iTrader: (13)

Jim, were ur heads milled, and what gaskets are u using?.

vettenuts

iTrader: (4)

Minimum recommended values are 0.080" intake and 0.100" exhaust. One note on the values. For the intake valve, it is usually chasing the piston down the cylinder so you may be able to run a little tighter. On the exhaust, the piston is chasing the valve as it closes so you may want to have the minimum here. Good springs and valve train control are mandatory. Also, don't forget the entire valve train is a system of springs with one of the most flexible being the pushrod.

jt76

iTrader: (10)

its not for my car... But the car in question has heads milled to 59cc, running a GM MLS gasket, a 242/244 vindicator cam and already has 90 thous flycuts on both intake and exhaust. It clears with a little bit of breathing room but just checking to be sure. The exhaust valve has a mile of clearance.

Sales4@Texas-Speed

iTrader: (4)

Vettenuts has it right. .080" and .100" are usually what we are looking for. Of course you can go a little less if you want but to be safe you want to make sure there is some decent room.

z28241

iTrader: (13)

we did clay method with no flycutting on mine and the closeness was so close probably what ur experiencing, but it didnt bust thru the clay so we assembled it and i have no issues, about 6k miles since swap.

jt76

iTrader: (10)

I always heard that rule of thumb, you want a little bit more room with a 6sp vs an auto. When i clayed mine, the valves busted right through the clay :



With this car, i cut through the clay with a razor blade and measured with feeler gauges, looks to be aprox .090 of clearance on the intake, a TON on the exhaust. I think we are good to go, going off the ideal readings people have posted here.

z28241

iTrader: (13)

.090 you are good..