bad geometry?

[Ronald D, Rains]

I have a friend in Midland that is working on the engine for chapparral 1 that is going into the petroleum museum in midland. This is a sleeved engine that I believe is .44 bore drysump with the oil pump on the cam drive gear, it has new style GM "D" port heads. He doesn't know anything about the specs on the cam so he sent the old cam to ISKY, they didn't have a blank so they picked some simular grind. After about 30 min at 3000 RPM, the cam lost 3 lobes. The failure looked like one was just scraped off and the other two lifters were badly cupped and the lobes rounded. I don't know much about the early alum (non ZR1) engines but I have pictures if anyone has knowledge of them.
Thanks

[Robert Willis]

Re: bad geometry?

It sounds like valve springs that had to much seat preasure or the cam was ground wrong. Probably the springs. BOB

http://members.kos.net/willisb/

[Robert Willis]

Re: bad geometry?

It sounds like valve springs that had to much seat preasure or the cam was ground wrong. Probably the springs. BOB

http://members.kos.net/willisb/

[John H.]

Re: bad geometry?

I learned a long time ago to break in nasty cams with high-pressure or dual springs using single stock springs, then change to the nasty-spec springs after the cam and lifters learned to like each other

[John H.]

Re: bad geometry?

I learned a long time ago to break in nasty cams with high-pressure or dual springs using single stock springs, then change to the nasty-spec springs after the cam and lifters learned to like each other

[Clem Z.]

Re: bad geometry?

on BB chevys with flat tappet cams i always ground .003 deep flat on the side of the tappet from the center groove to the bottom of the lifter so more oil will flow to the tappet cam lobe interface. this can be done on a surface grinder. cam companies now sell a grooving tool to groove the tappet bore in the block which does the same thing.

[Clem Z.]

Re: bad geometry?

on BB chevys with flat tappet cams i always ground .003 deep flat on the side of the tappet from the center groove to the bottom of the lifter so more oil will flow to the tappet cam lobe interface. this can be done on a surface grinder. cam companies now sell a grooving tool to groove the tappet bore in the block which does the same thing.

[Clem Z.]

PS

if you want to get technical go to www.off-road.com/chevy/reviews/bbc_oiler

[Clem Z.]

PS

if you want to get technical go to www.off-road.com/chevy/reviews/bbc_oiler