the car is an '84 TA, with a 305 HO engine,the first engine was destroyed when the balancer seperated and chewed through the timing cover and ripped the chain off. I've heard that it's a non interference engine,but whatever happened it messsed it up bad enough to need a new engine,so I got a new longblock and a new balancer.....upon taking the new engine out,I noticed that the black outer section of the new balancer has begun to "walk" backwards along the crank! only about 1/8"-1/4" for now with only 11k miles on the engine,why is the balancer seperating?? most likely,I'm not putting the 305 back in this time.....I think it may be junk,I'll be going for a 350,327,383....or something cool. how can I avoid this rediculous and potentialy disasterous,as seen already,problem with the harmonic balancer???

 

I'm still not to sure of what your desribing but it sounds like either your rubber is wearing and the outer part of the balancer is sliding back into the timing chain cover, or the key way is fatigued and is allowing for the whole balancer to slide back on the crank. The only way I could see the last problem happening is if the keyway is chewed up or the slot it fits into is missing the stop. If its the rubber wearing away then just replace the balancer. Get the new engine internally balanced and the harmonic balancer will not take as much of a beating. They usually come from the factory balanced but I would take it to a machine shop. Most will precision balance the bottom end for around $200.

 

the first one described,the rubber is wearing and it's sliding back into the timing chain cover. is this comon with the 305 HO engines? I've never heard of this with other engines.

 

Actually its very common. It happened to me when I had the original 305 and it first wore a hole in the timing chain cover. So then I replaced it and about 4 months later the crank bolt came out causing the harmonic balancer to fly off which in turn stripped the keyway and cracked the crank!!! When we tore the engine down (this was after welding the balancer on to the crank a I was desperate!!) after hearing rod knock...and to my dismay the crank had a crack in it (next to one of the counter weights). Anyway my friend had a 305 and had the same problem I did (harmonic balancer coming apart) so I guess its pretty common. We both ended up buying GM crate engines. I haven't had the problem since.

 

I had the same problem in my 85 305 tpi, the balancer wore a hole in the timing chain cover. I purchased a new one from summit and never had the problem again.

 

Same thing happend to my 86 305TPI about a year ago, but I was under the car changing the oil and happend to peek up there and noticed something was wrong before it had really chewed the timing cover any. It was just scraped.
So, I just bought a new one and it is fine.

Seems to be more common than what I thought...?


Ken