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Author Topic:   Cam timing
Dirt Roller

Total posts: 6
posted January 22, 2003 12:00 AM
Has anyone degreed a cam and known the cranking pressure , advanced or retarded the cam timing , then re-degreed and checked cranking pressure again?
I need to find out APPROX. how much cranking pressure gets affected per degree of later intake valve closing point.
Sorry for no intro first , ill catch up with that soon...kinda tired tonight.

Dirt Full Roller

Total posts: 31
posted January 22, 2003 10:17 PM
we lowered our cranking compression by over 15lbs with a 4 degree retarded cam. It ran better too!!!!!!!

Dirt Roller

Total posts: 6
posted January 22, 2003 11:28 PM
You are a god. Thank you. I have been looking from one side of the earth to the other for that answer!
The long gone person who assembled my engine installed the cam straight up and it put the centerline at 100 degrees. My cam specs call for 106. This made my piston to valve clearance .008 and cranking pressure at 215. The motor is supposed to be for 91 octane. I retarded the cam timing at the crank sprocket and it brought the centerline to 106.5. This gave me piston to valve clearance of .054. I needed to find out how that affects cranking compression and now I know. I think I may retard it another 2 degrees to give me even lower cranking compression and should bring piston to valve just perfect.
Thanks bud!

Dirt Freak

Total posts: 467
posted January 23, 2003 06:04 PM
.054" valve to piston clearance is not enough . You need a bare minimum of .080" on the intake valve , and .100" exhaust on the exhaust valve . .054" will hit at some point .


Hendren Racing Engines
Rutherfordton , NC

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