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Discussion Starter #1
First I would like to say Hi to everyone, it's nice to see a forum dedicated to Elky's!

I have a 78 El Camino with a destroked 305. It has a 327 crank in it and the harmonic balancer is going out. I can turn the fan belt about 20-30 degrees both ways without turning the crank! I don't know how long I've been driving this way.

What I was wondering is what size balancer can I put on it? I see two different sizes advertised 6" 0r 8".

Is a damper the same thing as a harmonic balancer?

What's a good race balancer that an entry level bracket racer would use?

GM wants almost $100 for a new one and I thought about buying a used racing one from E-Bay.

Thanks, Doug. :D
 

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87 Choo Choo
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What's moving ? The entire balancer or just the outer portion ?

Have you check to see if the crank key has been damaged or is missing ?
 

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Discussion Starter #5
I haven't pulled it off yet but I'm guessing it has some type of damage. It was all in good shape when I built the motor.

All this time I thought I had a problem with my valvetrain. it sounded like an old loose motor. I was removing the power steering when I found the fan belt would turn a little. Never had this type of problem before so there's no telling how long I've been driving this way!

I bought a puller yesterday and I'll probably work on it tomorrow on my day off.

I've been looking on E-bay for a racing damper and they seem to be costly. I think I'll probably go stock but maybe a new one from GM.

This is almost a stock motor so I would rather spend $200 on something else. Plus, if this motor happens to go bad then that would give me the reason I was looking for to get my 396 running.
 

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Try www.summitracing.com they have new harmonic dampers, pt# sum-161350 262 to 400 internal balance 6 3\4 diameter OEM damper. $59.99 or 8 in. #sum 161358 $61.99. They have others also just put "harmonic damper" on the parts search.
 

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I have a 78 El Camino with a destroked 305. It has a 327 crank in it and the harmonic balancer is going out. I can turn the fan belt about 20-30 degrees both ways without turning the crank! I don't know how long I've been driving this way.



There is one more thing to consider, in addition to a missing crank key. If you find that the key is not missing and the balancer is snug on the crank snout, the problem could be a stretched timing chain.
The belt pulley/pulleys are bolted to the inner ring of the balancer, not the outer. If the outer ring is the loose one, the rubber between the inner and outer ring is shot and the only thing to do is to replace the balancer before the outer ring explodes and puts a large dent in the hood.
If the outer ring is tight, try this. Remove the distributor cap and rotate the crank by hand and look at the rotor. If you can rotate the crank in either direction somewhat and the rotor stays still, you may have a timing chain that is stretched beyond usable limits. You mentioned that you thought you had valvetrain problems and a stretched timing chain will throw off your valve timing. Are you experiencing rough idle, no matter how much the carb is tweaked? Missing at higher RPMs? Problems adjusting the timing? Any rattling sound at curb idle?
Factory timing chains (no matter which automaker's) are manufactured with low manufacturing cost and silence in mind, unfortunately, they don't last long when the engine has been improved in other areas.
When engine blocks are align bored, the distance between the crank and the cam will be shorter and even a new chain will have too much slack in it. If memory serves me correctly, Cloyes offers chains that are a tad shorter to deal with this kind of problem. Good luck and let us know what you find out. :wink:
 
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