Does milling a head affect cam timing?Also...
11-30-2002, 01:01 AM
#2
Addict
Rennlist Member
Rennlist Member
Head becomes closer to the block, therefore bringing the cam closer to the block as well. That diffrence changes the distance from the crank pully and the cam pully, but the belt length does not change.
Depending how much it is milled depends on how far off it will be.
I have heard a few thousants off the head can be of several degrees of cam timing, depending on the car. I know this was a particular problem with 2.2 Mopars. (a crowd I used to be in big time, a little less nowdays)
Depending how much it is milled depends on how far off it will be.
I have heard a few thousants off the head can be of several degrees of cam timing, depending on the car. I know this was a particular problem with 2.2 Mopars. (a crowd I used to be in big time, a little less nowdays)
11-30-2002, 04:01 AM
#3
Race Director
[quote]Originally posted by Perry 951:
<strong>Head becomes closer to the block, therefore bringing the cam closer to the block as well. That diffrence changes the distance from the crank pully and the cam pully, but the belt length does not change.</strong><hr></blockquote>
Correct. Just to add the missing piece, when you tension the belt (or chain on engines equipped with one) the tops of the cam will be pulled in the direction of the tensioner.
The use of an offset key will correct cam timing (or of course adjustable cam gears).
<strong>Head becomes closer to the block, therefore bringing the cam closer to the block as well. That diffrence changes the distance from the crank pully and the cam pully, but the belt length does not change.</strong><hr></blockquote>
Correct. Just to add the missing piece, when you tension the belt (or chain on engines equipped with one) the tops of the cam will be pulled in the direction of the tensioner.
The use of an offset key will correct cam timing (or of course adjustable cam gears).
11-30-2002, 04:43 AM
#4
Race Director
"Wondering how milling a head would affect cam timing?"
Theoretically yes, in actuality the amount is miniscule. When I shaved my head by 0.050", the difference was less than 1/4 of a belt tooth; about 2.3 degrees retarded. This is in the direction you want for high-end power anyway. I would be more concerned with valve-to-piston clearance than with timing, especially if you're running aftermarket cams.
Theoretically yes, in actuality the amount is miniscule. When I shaved my head by 0.050", the difference was less than 1/4 of a belt tooth; about 2.3 degrees retarded. This is in the direction you want for high-end power anyway. I would be more concerned with valve-to-piston clearance than with timing, especially if you're running aftermarket cams.
