I just freshened my 80,000 mile '87 GN motor. When I tore the motor down, all of the journals looked good and none of the bearings showed abnormal wear (probably didn't need to be replaced), but I replaced them all anyways with standard size bearings. I also installed a Comp Cams 218* cam, CC lifters, CC springs, Edelbrock timing chain, all of the usual GN motor updates for seals, cam button, etc.
I broke in the cam this morning, and right at the end of break in started to hear a strange noise. Shut down the motor, let it cool, hooked up an oil pressure gauge and restarted to check oil pressure and it looked fine (~40psi @ 2000RPM). The motor didn't make any strange sounds at this point. Finished putting everything together and took it for a spin around the block. Car idles great, but when it hits about 3000 RPM, it starts knocking.
I've undone and redone the torque converter bolts, so it can't be that. I'm sure it's coming from the bottom end of the car. Is there something else I should check before I pull the pan off to look at the bearings?
Any and all comments are appreciated.
- Josh
Did you plastic gauge the bearings. GM was throwing away too many cranks. In 1976 they started custom grinding them. .003 under size was acceceptable. Also they would use a std. upper with a .003 lower on the rods if thats what it took. What I am saying is the journals are not standard on production line cranks. All cranks from GMSPO (GM Parts) ARE standard. You may have to custom fit your bearings like GM did.
Just a thought
Phil