1995 Trans Am
- high lift cam
- electric water pump
- Summit double roller timing chain

at 145k I blew the car's original opti. I replaced it and this opti died in another 150 miles...one interesting thing after this install: I heard a periodic grinding from the timing cover area, as if part of the timing chain assemply was scraping the timing cover despite the fact that it hadn't for 5000 miles since its install. I have a Summit true double roller timing chain, so it did require some clearancing on the timing cover. I suspected that a bolt had loosened from the timing gear and thus timing cover scraping had somehow caused an oscillation which blew out the bearings in the brand new opti, so I replaced it with another opti and tightened all bolts with loctite. At that point I also installed an MSD blaster coil, though I doubt this alone without an MSD 6A or 6AL could destroy the opti quickly. That opti lasted 1400 miles until the present--the T/A died again Saturday. It started out as a very high miss, then worked its way down to all RPMs except idling. The car stutters and backfires like crazy, won't go anywhere--I'm sure it's the opti again.

So...any hypotheses about what keeps destroying my optisparks? What sort of destructive oscillations can get transferred to an opti? It really seems like the cam pin is awfully solid with no play, so how could it be killing optis? It's especially strange that for 5000 miles post-double-roller-install the opti was fine, then it finally died. And it IS the innards of the optisparks that get toasted...when you remove one you can hardly even rotate the metal cam pin acceptor, and if you can tons of junk rattles around on the inside. I am desperate for help on this problem, as I have given the car to a higher-end local auto shop in hopes that they can find the root cause...I'm afraid this may be over their heads though. Thank you SO much for replies!

 

If you have not checked the length of the dowel pin on your aftermarket cam, you should. Being too long is the cause of a quick opti death. I have seen people go through several optis before they asked and figured this out.

 

Assuming that it is an incorrect length, how do I shorten it? I mean, will a steel file do anything? Seems like the cam is hardened steel...how about a stone dremel bit?

 

Some people are able to tap it in, but I am not sure I would do that with the cam installed. You can grind the pin to make it shorter. Just mask it off to keep any particles out of the engine.

 

my friend had an idea of using a "thrust gauge" to check the cam's position relative to the block? Could a scraping timing chain cause an oscillation and thus screw up something with the cam, moving it from its correct position? Also, what is the correct pin length, 5/8"?