[CJDave]

/wwwthreads_images/icons/frown.gif This is a HUGE problem with the 304s, and nobody seems to have the answer. Of course there is nothing to KEEP the cam from walking to begin with except your good looks. Why not call American Performance in FLA....407-632-8299...and describe the problem. If anyone knows why it should be them. I have a theory....but it is only that.....My theory is that the cam HYDRAULICS out of the last bearing....you know the one...it has a soft plug behind it...when the oil seeps by the cam bearing and into that cavity, it builds pressure and the cam is pushed out. I don't know if the two-year-old who designed the AMC V8 oiling system put a relief hole or not to relieve the pressure, but American Performance would surely know./wwwthreads_images/icons/crazy.gif

CJDave

 

[CJDave]

/wwwthreads_images/icons/tongue.gif In that case, I would have to go along with the bearing theory. If both cam and lifters are different, what else is IN the system except the cam bearings that could make it do that. Oh, another possibility....check the crankshaft end play....make sure it isn't pulling the cam out. The newer the chain, the worse it would be. Just a thought./wwwthreads_images/icons/crazy.gif

CJDave

 

[CJDave]

/wwwthreads_images/icons/tongue.gif But the lifters and cam are not the same ones, so whatever is causing it is independent of the lifters or cam. The alignment of the chain drive IS critical, maybe take a good look at that, AND check the crank end play. /wwwthreads_images/icons/crazy.gif

CJDave

 

[CJDave]

/wwwthreads_images/icons/tongue.gif That is a very critical piece of information JF1. So there IS an oil relief to keep from pushing the cam out of the bearing box at the rear. AND...it appears that the distributor drive is critical to cam end play.....as in the bushings need to be stellar in both the oil pump and the distributor. That might be a good place to start looking.....at the distributor shaft bushings. We think the cam walks and destroys the distributor drive gear, biut it is actually the distributor which deflects and does it? Hmmmm...? /wwwthreads_images/icons/crazy.gif

CJDave

 

[CJDave]

/wwwthreads_images/icons/tongue.gif The gears suffer because the centerlines of the two shafts no longer perfectly intersect, , and there is very little tooth engagement remaining, so the load from the oil pump becomes more than the very tips of the gear teeth can handle and it tears away the metal./wwwthreads_images/icons/frown.gif

CJDave

 

[CJDave]

/wwwthreads_images/icons/tongue.gif All the good engines have the lifter bores offset to the cam lobe to cause rotation except.......SMALL BLOCK CHEVYs! Yep....they don't have enough offset. SO......you NEVER let a SB Chevy idle......the lifters are scuffing the cam. Thankfully, the AMCs are offset enough to cause rotation./wwwthreads_images/icons/tongue.gif

CJDave

 

[CJDave]

/wwwthreads_images/icons/crazy.gif I've learned not to underestimate the end play on crankshafts...ESPECIALLY with real heavy manual clutches, it's easy to wear out the thrust surface and have the crank walking back and forth in the mains. That could easily overcome the feeble gear pressure that is used to hold the cam in place. CHECK THE CRANK./wwwthreads_images/icons/crazy.gif

CJDave