Nitrided Cam
 

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

Re: Nitrided Cam
 

Back in the early 70's in modified eliminator I had a roller cam that came from Jenkins. On the second pass I return to the pits, push in the clutch pedal and the motor would shut off. Pulled the motor and the cam was locked in the bearings. Checked the cam and it was straight. New bearing and back out the next weekend. After the 2nd pass the same thing again. Sent the cam back to general kinetics and they said there was nothing wrong. They made the statment that Jenkins does some strange things. Tried to solve the issue two more time with the same result. I finally gave up. I kept trying because that first pass each time my MPH was 2.5 more then usual. Something had to be done to the ramps on the cam that caused it to hammer the cam bearings and sieze the cam.

Re: Nitrided Cam
 

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

Re: Nitrided Cam
 

Jamie,
Did you happen to measure the journals on the Bullet cam compared to the one that turns easily ? Over the years I have seen some differences in sizes once in a while. I always try to have the cam that is going to be used in the engine when I install cam bearings in a block.

I have had the best luck with Durabond cam bearings.

One more thing, were the oil holes in the bearings in the correct position ? Should be in the approx 2 oclock area looking from the front of the car.

Re: Nitrided Cam
 

Talked with Bullet this morning. Valve spring pressure was way off, too light, causing out of control valve train which bent valves and in turn tweaked the camshaft. I bought the engine new 0 passes. Now I need a cam that is 6-10 weeks out. Sending this one in to have repaired

Re: Nitrided Cam
 

I ran a nitrided Bullet cam in my Cleveland for a short time. I changed it because the particular profile that was chosen just didn't make enough power. What I did notice about the nitriding was that when I adjusted the valves, when turning the engine over, it squeaked. Changed the cam, the squeak went away. No biggie, just weird.

Re: Nitrided Cam
 

I'm with BillK on this...
Insufficient oil flow to the cam bearings

Re: Nitrided Cam
 

Please check cam bearing oil feed hole location.


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