Quote:
Originally Posted by jamie2370
Long story....Fresh stocker 305 sbc done by a reputable builder. I am on my 3rd set of exhaust valves due to wrong valve springs(only 130lbs seat, not PAC 1409x 175lbs) Anyway, pulled engine to verify all clearances(PTV, PTH) and cam settings(Done by an experienced person). All came back where they needed to be. Well, had to pull the oil pan the reinstall timing cover...metal goop in pan, pulled lifters to check them..all good, tried to pull cam. It would not turn and had to pry it out thru the lifter bores. Cam bearings are horrible. Tried another cam I have and it installed and turned as normal. Cam I took out is a Bullet Nitrided cam(it is ALL black). I think cam is bent. Is this an issue with Nitriding or is there a different bearing for those cams?? I honestly have never had a bent sbc cam in 30yrs of racing
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Good morning Jamie,
Back in the nineties when the oil company's dropped the Zinc from the oil I eat a cast cam in one of my 350 Chevy engines. I didn't find it till I tried to remove the cam to try another cam. I had to pry the cam out of the block. That block had the cam tunnel line honed and Bronze lifter bushings installed. At the time it seemed that the cam bearing eat its way into the journal, the cam was checked and found to be .001 runout on the middle journal ( journal #4) went bad. We went through a series of cam journal diameters and bearing materials.
We were told at the time that the Oversized Bearings used a different material. Needless to say that block is still sitting in the corner and I've moved on to different blocks. Maybe your builder needs to try a different Cam Bearing Mfg., I switched to Coated bearings and "Thankfully" haven't had anymore of those problems. Maybe have the cam checked for run out before installing and try to measure the clearance between the journal and the installed bearing. All the cams I've user over the years were straight, maybe it wouldn't be a bad idea to check them in some "V" blocks and be one more thing on the engine build check list.
Respectfully,
Henry Kunz 1534 H/SA