valve/piston clearance
10-09-2009, 06:43 AM
#1
valve/piston clearance finally putting my 403 together, dummy'ed up a couple lifters as mech. so they wont compress, clayed the pistons, installed a used (compressed) head gasket, adj. the valves to zero, and rotated it thru a couple cycles
when i pulled it down, didnt see any signs of valve indenting
403, AFR 225's, EPP cam, Wiseco pistons
i thought for sure i would see at least a small touch, and i did it a sec time with more of a glob of clay, still nothing-i know theres other ways of checking the clearance, thru certain degrees of rotation, but i have always preferred clay
do the LS engines have that much clearance, and yes i degreed the cam in
when i pulled it down, didnt see any signs of valve indenting
403, AFR 225's, EPP cam, Wiseco pistons
i thought for sure i would see at least a small touch, and i did it a sec time with more of a glob of clay, still nothing-i know theres other ways of checking the clearance, thru certain degrees of rotation, but i have always preferred clay
do the LS engines have that much clearance, and yes i degreed the cam in
10-09-2009, 09:50 AM
#3
TECH Regular
Hey there, yes our valve pockets are pretty deep. Up to about 228@.050 or so...little if any relief is needed. Our pistons have valve pockets in the .250" deep range on average -so you often end up with a mile of clearance with a mild cam.
10 atdc for the intake and 10btdc on the exhaust are a good places to check for P to V. If you have checking springs, you can roll the engine over to that point and easily check actual clearance with a dial indicator.and pushing the retainer down with your finger. This is pretty cool because you see what happens when you advance and retard the camshaft. Plan B is clay. Plan C if you don't have checking springs or a dial indicator is putting .060 feeler gauges on the intake and .090 on the exhaust between the valve stem and the rocker (rocker set to normal height) to simulate needed clearance-and roll the motor over. This isn't a great way to do things because sometimes you can't feel a valve pushing on a piston, but it's better than not doing it at all.
The last thing is the circumfrence of the valve is normally where the problem occurs....it's fine under the center of a valve but digs in the perimeter of the valve pocket and either clearances itself or busts the head off of a valve. This is most common with angle milled heads.
With our pockets (especially being LS multifit pockets) -they likely give you a mile of radial clearance.
Thanks for using Wiseco! -Brian Nutter
10 atdc for the intake and 10btdc on the exhaust are a good places to check for P to V. If you have checking springs, you can roll the engine over to that point and easily check actual clearance with a dial indicator.and pushing the retainer down with your finger. This is pretty cool because you see what happens when you advance and retard the camshaft. Plan B is clay. Plan C if you don't have checking springs or a dial indicator is putting .060 feeler gauges on the intake and .090 on the exhaust between the valve stem and the rocker (rocker set to normal height) to simulate needed clearance-and roll the motor over. This isn't a great way to do things because sometimes you can't feel a valve pushing on a piston, but it's better than not doing it at all.
The last thing is the circumfrence of the valve is normally where the problem occurs....it's fine under the center of a valve but digs in the perimeter of the valve pocket and either clearances itself or busts the head off of a valve. This is most common with angle milled heads.
With our pockets (especially being LS multifit pockets) -they likely give you a mile of radial clearance.
Thanks for using Wiseco! -Brian Nutter
10-09-2009, 10:22 AM
#4
i'll double ck them using your method, even with the clay above the piston it didnt leave a mark, but with your specs i'll try that just as a backup
the old 6.0 also had Wiseco pistons, beat on them for 1 1/2 years under boost, still like new-actually gonna save the old engine for my truck if it ever wears out, lol
thanks for a great piston
the old 6.0 also had Wiseco pistons, beat on them for 1 1/2 years under boost, still like new-actually gonna save the old engine for my truck if it ever wears out, lol
thanks for a great piston
