Camshaft endplay carnage

[Lightfoot]

I have been running my stroker for about three years now, and have around 15k miles on it. It ran great until recently when it started to develop a knock under load. It got pretty bad, so I decided to tear it down. I bought it as a long block, so this is the first time I have been inside this particular engine. The two front main crank bearings are worn bad, showing completely copper, with significant scoring. The timing chain was fairly loose, and the teeth on the gears are chewed up. One ear of the snubber is broken off. I was thinking that the timing chain failed, sending shards of steel into the mains, so I dug a little deeper. Crankshaft end play was not significant, so I moved on to the camshaft. I found evidence that the cam bolt had made contact with the timing cover, and that the spring loaded rod had actually worn into the aluminum button a bit as well. Doing some research, I found that this can be fixed by eliminating the spring, and using a longer rod cut to set end play manually. I plan to do this on my rebuild, however my question comes in on the other end of the cam. I found that the back end of the cam had also worn itself a groove into the "freeze plug" that keeps it from coming out the back of the engine. Is this normal, and if so has anyone come up with a way to prevent it? I can't imagine the shards of freeze plug getting into the oil are good for anything.
Any input is appreciated,
Thanks
Lightfoot

[604rail_king]

sorry to hear the news.

cam wear on the rear frost plug is not normal ... but it sounds like you had some excessive cam movement. whats your cam and head setup ?

i recently just picked up my assembled short block from my machine shop, and with running a mild Comp Cam (201) i opted to have the cam spring/pin setup replaced with a solid pin. my machinist made it and allowed for .005 clearance. much less than what the stock spring/pin would allow for.

here's what it looks like so you can show your machinist or make your own.

[SilverXJ]

The cams haft rubbing the cam tunnel plug is not normal. Either the plug was installed too far, or the cam cog(or engine block) had wear on the back side that let the cam move rearward. Another possibility in your failures is that the camshaft was sticking out of the block too far due to the cam plug which caused an alignment issue.

Sandrail, that looks pretty slick. What is it made out of?

[Lightfoot]

Thanks for the replies,
Silverxj, I think you hit it right on the head. I put things back together and determined the rear plug was keeping the cam forward about 1/10th of an inch. This misalignment of the timing gears caused the chain to wear very hard. It looks to me that after the rebuild the cam may have actually been rubbing on the timing cover before the engine was even started. Eventually it wore a grove into the plug and moved itself back a bit. Ill still probably set endplay manually, so thanks for the idea on the machined part. It sucks to think one expansion plug installed too deep cost me a motor.
lightfoot

[SilverXJ]

Check the distributor and cam gear for wear as well.