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Author Topic:   valve to piston clearance
Dirt Full Roller

Total posts: 34
posted April 24, 2002 06:32 AM
In the rules for my class, I can mill the heads any amount. I am wondering what minimum clearance i should shoot for between the valves and the piston. I want to create as much compression as possible but do not want any valve to piston contact. It is a 2.3 liter ford motor.

Thanks in advance. BTW Im running a .450 lift cam but I dont think that makes a difference. I intend on using putty on the top of the cylinders and measure the depth of the mashed putty to determine the clearance unless there is a method that someone can suggest that is better.


[This message has been edited by TRAP (edited April 24, 2002).]

Dirt Freak

Total posts: 298
posted April 24, 2002 06:56 AM
TRAP, we used to mill the head down to where the intake bolt holes showed threads thur the head surface! now i know thats alot but it works, we ran bigger cams than that and had no problems with flatops but you must make sure your cam is degreed in perfectly, and i suggest using real lite valve springs to mock up the assembly rotate the motor very slowly and push the springs with your fingers down till the valve touches the piston, measure the clearance at that point, should have at least .060 on exhaust and slightly less on intake. this method is much more accurate than clay. just dont turn engine over with out the cam being timed in correctly. good luck ---------ford5

Dirt Freak

Total posts: 233
posted April 24, 2002 09:55 AM
I have taken .180 off. You can mill all the way to the intake bolts without problems. I do it with larger cams than you have. You'll be limited by the intake bolts before you have a problem with valve to piston clearance. As ford said, make sure your timing is correct. You won't be able to get away with slipping the timing belt any more.

Dirt Maniac

Total posts: 199
posted April 24, 2002 10:57 PM
Everything both of you have said is right. Let me add that on a 2.3 Ford with such a milled head the valve clearance will go to nothing if the adjustable cam timing gear is adjusted to more than about 8 degrees. This is not to say don't check. Just remember when you want to change timing at the track. SLEEPY

Dirt Full Roller

Total posts: 34
posted April 25, 2002 11:59 AM
Thanks for the input guys, I just dont want to jump into something blindly and have to start over. I know you guys can relate to racing under a budget. I have no sponsorship and am doing it all myself. I occasionally have a few friends help me out with odd and end stuff but the rest im a lone ranger. So all advice is greatly appreciated. I have to give the machinist here locally credit for having the patience to listen to alot of dumb questions. But as he said the only dumb question is the one that wasnt asked and a mistake occurs.

Thanks again


[This message has been edited by TRAP (edited April 25, 2002).]

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