cam gear bkoke again

Are you sure you are getting oil to the cam gear?   Lots of problems previously documented on the forum about aftermarket cams (lacking proper oiling holes/groove), cam timing sprockets (oil passage plugged with casting flash/not aligned properly with oiling hole in cam face), and gunk in the four small pinholes in the cam dizzy gear that allow oil to get to the gear teeth.

I bought a matched set of Bulltear gears. They were installed in the correct location, not backwards. They were both coated with assembly lube. My oil pump shaft is not binding. The distributor gear does not appear to have any damage at all while the bolt on cam gear is missing several teeth and the remaining teeth are 1/2 thickness and evenly worn about 2/3 deep. I am running a Comp Cam that has been in this motor for 5000 miles. I was running a stock cam gear the first time it went with the Mallory distributor gear which had a smaller roll pin than the Bulltear replacement gear. I did not drill out the hole in the gear, only the Mallory shaft. The cam gear that I used on the rebuilt 401 was a used gear from another motor so it had way more than the 5000 miles I put on it. The Bulltear gear only made it about 300 miles. I don't know why it went so fast at this point but I really don't like having to do this repair this often. The other AMC motors I've had this happen to in the past were completely different used motors with all stock components and I didn't use anything from those motors on this 401 since they were all left behind years ago in Michigan. They were just used motors, I did not build them. I am leaning toward a bad timing cover or lack of lubrication. I have had good oil pressure and the oil was changed after the last gear replacement. I have a deep pan and have not run it low. The motor has only been driven back and forth to work, about 2 miles each way since the gear swap. It has been backfireing when the timing slips off 10 adv. I have a rebuilder core 360 sitting here that I might snag the cover off, but I don't know the condition yet. I have used the same double roller timeing chain setup since the first rebuild. No mater what the cause, I will still need to purchase another matched set of gears but since they are claimed to both be the same hardness, I can't figure out why only the cam gear is destroyed with no damage to the distributor gear. Distributor gears are much easier to change.

Once back together with replacement dizzy drive gears and the timimg cover installed, leave off the fuel pump, use a pre-oiling tool to run the oil pump, and look up through the fuel pump hole in the timimg cover to see that oil is running out of and covers the camshaft mounted distributor drive gear.  This is a way to confirm the dizzy drive gear is getting oiled.  Have you seen the YouTube videos where someone cut a large round hole in a timing cover centered on the camshaft and uses a oil priming tool to show the amount of stock dizzy drive gear oiling ?  The oil is very visible in the videos since it is kinda white colored from having water in the oil.  It most obviously has to be a very frustrating situation. 

Edited by PHAT69AMX - Oct/21/2008 at 5:46am

The Bulltear gears looked great when I installed them so I was actually looking for another cause of the failure and I found it. After reading about the oil passage behind the upper timing gear, I pulled my chain off. The hole in my Comp Cam I purchased abot 10 years ago and the timing chain gear do not line up at all. With the cam keyway straight up, the oil supply hole is at 10 o'clock, looking at it from the front. The grove in the back of the timing chain gear as well as the slot are directly opposite the keyway, or 6 o'clock. The grove and slot are at a pretty sharp angle and could use a little relief cut in but the grove in the back of the gear is so far away from the oil supply from the cam that I most likely wasn't getting anthing but splash on the cam gear. I'm suprised that the original cam gear went 5000 miles. I have 2 solutions in mind. One is to have a circular grove cut in tghe back of my existing aftermarket gear, but I don't have the tools for this. Two is to purchase a timing set that already has this feature. I will be purchasing another matched set of Bulltear gears and a new timing chain set since redrilling the cam supply hole is not really an option either. I thought that the cam gear looked a little dry when I pulled it but since I usually wipe down parts as I pull them I couldn't be sure. Does Bulltear carry the ball grooved timing chain set?

pictures anyone?  I've got a brand new timing set resting on the cam and crank snouts and before it go any further, i'd sure like to know what to look for.