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Discussion Starter #1
I had about 60 1/8th mile passes on a new Comp belt drive and the belt broke this past weekend. Several weeks ago, a friend had a Comp belt turn loose on him causing significant damage. I haven't gotten into mine yet to see what carnage I have, the belt broke as the car was idling onto the return road so hopefully not too bad.

Both engines are BBC, standard cam location. My question is, is this a problem with the Comp belt drives or were we just the unlucky ones. If it's a recurring problem, I'd rather make the switch to a Jesel drive while I have the engine out for freshening.

Thanks,
Martin
 

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How are the bearings doing in the idler pulley? If you calculate the RPM at which that idler pulley is spinning it's probably around 26,000rpm. Now if you look up the speed the bearing's max was rated to it'll be around the same (26,000rpm). That means that those things are generating a lot of heat, friction, and possibly slipping across the belt from the friction. I know Jesel likes to use the NSK "6002ZZ" for their bearings and I would replace them anytime the belt is off. Check to see if there is much play in them and if they are worn it might be a contributing factor to the belt snapping.

I had about 60 1/8th mile passes on a new Comp belt drive and the belt broke this past weekend. Several weeks ago, a friend had a Comp belt turn loose on him causing significant damage. I haven't gotten into mine yet to see what carnage I have, the belt broke as the car was idling onto the return road so hopefully not too bad.

Both engines are BBC, standard cam location. My question is, is this a problem with the Comp belt drives or were we just the unlucky ones. If it's a recurring problem, I'd rather make the switch to a Jesel drive while I have the engine out for freshening.

Thanks,
Martin
 

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right after my oil pump broke the motor tossed a few rods & had a rocker busted in half after the piston hit the intake valve .
1 of the only good parts left on the motor was the Jesel belt & belt drive parts. the belt drive took the hit when the rocker broke & when the oil pump stopped working.
 

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I have 150 passes on mine and I checked the bearings over the winter, with over 100 passes at the time, and they were fine. No signs of any heat issues at all, no discoloration or grease weeping from the seals. I haven't heard of any issues with them from the builder I know who uses alot of them and I was just at his shop this morning. Did you have the belt tension set properly? I had to reduce the size of my roller when I built mine and others have had to be cut too to get the tension right. RM
 

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Discussion Starter #5
Thanks..

I have 150 passes on mine and I checked the bearings over the winter, with over 100 passes at the time, and they were fine. No signs of any heat issues at all, no discoloration or grease weeping from the seals. I haven't heard of any issues with them from the builder I know who uses alot of them and I was just at his shop this morning. Did you have the belt tension set properly? I had to reduce the size of my roller when I built mine and others have had to be cut too to get the tension right. RM
Thanks for the info, but I really couldn't answer your question regarding belt tension. My builder is as anal as they come, so I'm pretty sure that the belt tension was correct but who knows??? I'll be sure to mention it when I take it to him for freshening/repairs as well as replacing the idler as a maintenance item. Maybe it was just a fluke, but with 2 issues with the same manufacturer I had to ask. Certainly no flame intended towards Comp.

Thanks again,
Martin
 

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Hey if mine broke I'd be asking too. That's how we learn about problems. The bearings make me nervous too so I watch them but I haven't heard of any problems yet. RM
 

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Discussion Starter #7
Found the cause of the belt failure, phucking additional head stud in the lifter galley backed out and locked up the cam. Haven't assessed all the damage yet.

SHIT!

Martin
 

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Thanks for the follow up. Now I can still say I haven't heard of a belt failure without a cause. RM
 

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spun cam bearings

I just had a brand new engine eat the front three cam bearings and spin the rear two forward out of the block. The engine had less than two hours run time and those were only on the dyno. Everything was all new, but the belt drive or belt drive tension seems suspect. It was a Danny Bee belt drive on a SBF with fairly mild (.715-.679 lifts) solid roller in an R302 block. Would too much belt tension have been the probable cause for cam bearing failure in a new engine? Has anyone even HEARD of cam bearings going down in an engine? It's a new one on me.
 
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