And add coil bind into the mixture 
max valve lift
Safety Car
Joined: Apr 2005
Posts: 3,624
Likes: 431
From: Dale City VA
Maximum valve lift has nothing to do with piston to valve clearance. The piston is near BDC when the intake valve reaches maximum lift, and is commin up when the exhaust valve is at max lift, and as the exhaust valve closes the piston reaches TDC.
One part of what determines piston to valve clearance is how fast the intake valve opens off the seat and how fast the exhaust valve closes. Duration at .050 is a good indicator of how fast the opening rates of the valves are.
Another part is valve size and the pistons valve relif size/depth.
Yet another part is the camshafts intake and exhaust centerlines.
Will
One part of what determines piston to valve clearance is how fast the intake valve opens off the seat and how fast the exhaust valve closes. Duration at .050 is a good indicator of how fast the opening rates of the valves are.
Another part is valve size and the pistons valve relif size/depth.
Yet another part is the camshafts intake and exhaust centerlines.
Will
Race Director
Joined: Sep 2003
Posts: 16,839
Likes: 341
From: Database Error Indiana
On a stock motor, you don't want more than .550 lift. Problems come up other than piston contact. The valve retainer may hit the valve guide for a start. As Agent 86 said, Coil bind also a problem. Your heads and intake probably wont flow enough air to take advantage of more than .550 anyway unless you start spending lots of $$$$. Play it safe and stay at .520 or less and you should stay out of trouble.
Thread Starter
Advanced
Joined: Aug 2005
Posts: 63
Likes: 0
From: Elgin Minnesota
no kidding!
I'm well aware of the workings of the 4 stroke engine, I was hoping to hear from a few people on what they have ran. As I have a lingenfelter soilid roller I was contemplating slapping in a stock 85 short block w/ a pair of bowtie heads, superram, and 1 3/4 tpis headers.
cam specs are as follows: .587 lift I&E w/ 1.6 rockers , 236/244 at .050, 280/288 adv, 112lsa
cam specs are as follows: .587 lift I&E w/ 1.6 rockers , 236/244 at .050, 280/288 adv, 112lsa
Le Mans Master
Joined: Jul 1999
Posts: 8,683
Likes: 6
From: Phoenix AZ
Well, in that case...I ran some 1.7 rockers on a cam in my engine which gave it lift numbers of .575/.595 (roughly) and I had contact between the valves and the pistons. BUT, that was mainly because I was running larger valves in my heads and they did not fit into the valve releifs cut into the pistons. If I was running the stock valve sizes I would not have had the problem. Hope that helped you a bit. 
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