[Prowbar]

I then degreed the cam, as I was curious about the gear set vs the timing chain. I've seen in the manual that all camshaft timing events for the 401/478 occurred 6 degrees later than the 305/351. Made me think they retarded the camshaft 6 degrees with the timing gears. My camshaft had an intake center line of 108 and it installed at 115, so ended up with the cam 7 degrees retarded. That confirms my suspicions there. Should have communicated that to Mike when he ground my cam but oh well.

If I didn't install timing cover I could have tried to install the cam straight up or advance it somewhat by using a offset key or milling in a new keyway slot, but I don't know where the torque peak will be exactly so we'll see.

Retarding the cam moves the torque peak up, a general rule is that 4 degrees retarded moves the torque peak up 200 rpm, meaning I'd be looking at a 350-400 rpm shift on torque peak.

Makes sense for GMC to retard the camshaft in the bigger engines so they can use the same camshaft for all displacements. If all else equal, the bigger displacement with the same cam causes the torque peak to occur sooner, so they retard the cam to compensate.

Installed oil pump, pickup and RTV'd the oil pan spacer to the block. Then installed the oil pan with a cork gasket and RTV.



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Then installed the spin on oil filter housing with the GM 11 psi bypass valve. The bypass presses into the housing, used some green Loctite to ensure it doesn't come loose. I used some sandpaper and the milling machine table to sand the gasket surface flat.



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I ended up with something like this:



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Next up: top end.