Special Notes: GM 6.6L Duramax Cam Installation

[CPG Marketing]

Warning:
COMP Cams always recommends checking piston to valve clearance whenever installing a camshaft. Modern engine design dictates a compact combustion chamber and tight clearances. Tolerance stack or installation errors can result in interference and failure. COMP recommends 0.080” intake and 0.120” exhaust minimum piston to valve clearance in most applications.

Methods:
Best (Head Off) = Uses solid (roller or flat depending on applications) tappets, clay, a razor blade and calipers: Clay around the valve reliefs, install heads with used gaskets, assemble valve train with solid tappets and turn engine over slowly by hand with zero lash on hydraulic applications or recommended hot lash for solid cams. Use razor blade to slice the clay at the deepest indention and measure the thickness with your calipers.

Next Best (Head On) = Uses a solid follower, degree wheel and dial indicator and flowbench springs: Swap out to a solid follower if hydraulic and set lash to zero. For solid roller or flat applications, use the recommended lash. Install flowbench springs. Zero the degree wheel at compression TDC and check clearance at the following angles:

Exhaust = 20 BTDC, 15 BTDC, 10 BTDC and 5 BTDC
Intake = 5 ATDC, 10 ATDC, 15 ATDC and 20 ATDC

Clearance is determined by rotating the engine to the desired location, zeroing the indicator and pushing the retainer down with your hand gently until it contacts the piston, the measurement you have at that point is your piston to valve clearance for that location. Next rotate the engine to the next location and repeat the procedure until you find the closest location.