I am thinking of changing my cam to a solid with more lift. My lift right now is .490. How do I check for piston to valve clearance if I goto a 550 or so lift with the heads on?

One way, would be to use a dial indicator on the tip of your valve, you would probably want to remove the spring (valve) to do this. With your piston at TDC you could push the valve/s down and measure the clearance with the dial indicator. I think that would be the easiest way to do it woth the heads on and in the car. Just remember to add in the clearance to the measrement.

I was thinking of trying this method on my stock vortec 350 engine. How much should be deducted from the measurement of the travel of the valve stem from the seat to where it touches the piston to get an estimate of how much cam lift you could safely have ? Thanks, Ron.

None if it's a hy- cam and just the lash if it is a solid.

Then subtract, (what is it guy's?), .100" for the intake and .80" for the exhaust for running clearances??

At least I think this is how it's done??

pdq67

You want check piston to valve clearence from 20 degrees BTDC to 20 degrees ATDC on both intake and exhaust,the reason being is that the valves are closer to the piston at a point other than TDC. The intake is generally closest to the piston ATDC and the exhaust is closest BTDC. It just depends on lift and duration and really how fast the lobe ramp is accelerating (intake) or decelerating (exhaust) the valve.Hope this helps.