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Discussion Starter #1
Howdy people!

I was driving along nice and happy last Sunday when all of a sudden my engine died, (350) and wouldn't crank up... It would make odd sounds when cranking over.. So I dragged the Chevelle home, the only visible damage is the Harmonic Balancer which has lost it's internal rubber ring, and the outer part is spinning itself off towards the timing cover.. Cranking it over I hear a clicking rattling noise up front... It wants to start but sounds like the timing is just way off... So I took the valve covers off.. All the rocker arms move when I crank on it which eliminates the camshaft.. The timing chain must still be in one piece, but maybe stretch ed way bad or jumped a tooth or something..
So I'm going to replace the chain and balancer.. Is this a reasonable diagnoses, or should I expect something else? Appreciate any input...

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Scott, 20
Dallas, 70 Chevelle Malibu
 

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howdy Scott,
I would definetly replace that balancer! As for the real problem it could be lots of things(ingition,valve timing,fuel,etc.)

I think (never really tried it) that you can check the slack in the timing chain by removing the distrubiter cap and rotating the crank back and forth both directions while looking for movement(or a lack of movement) at the rotor button.The rotor in distrubiter is driven fron the back end of camshaft.If the crank moves more than a few degrees before the rotor begins to move then there would be too much slack.This might save you from having to remove the timing chain cover to look for wear. That cover is a real pain to get off and back on with the motor in the car,since oil pan will have to be lowered at least a half inch.
Good Luck

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Tony Leep
Scottsburg,Indiana
64SS Grocery Getter
ICQ 34163913
 

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If the chain and sprockets were stock GM, there's a good chance the upper sprocket has lost its plastic teeth. The worse case scenario is that the timing has retarded enough from the chain jumping to bend some of the valves from piston to valve interference.

About the only way to check without taking the entire engine down, is to remove the timing chani and replace the chain and sprocket assembly, at this time, the cam being out of time will be easily seen, then re-install the timing cover and give the engine a compression test. If there are cylinders with no compression, a leakdown test will show just what is damaged.

I use a double row timing chain and sprocket set for replacements. Much better than the stock single link and plastic upper sprocket sets, and darned near the same prices too.

Since the possibility of piston to valve interference is present in these engines, doing the test(s) will tell if there is actually the need for further disassembly (heads, etc).

Problems you might encounter with the heads are bent valve(s), bent pushrod(s), broken valve spring(s) (not very probable but possible), broken piston.

If the compression is OK, then you get a free get-out-of-jail pass.

Good luck with it.
 

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In addition to the other suggestions, find TDC on #1 and look at where your distributor is. If it way retarded you have a jumped chain. I would have told you to shoot it with a timing light when cranking, but it sounds like your timing marks on the damper may not be trusted.
 

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Discussion Starter #5
Yeah. the balancer broke off the timing tab, and is probably off a little.. I guess I'll just take it all apart thie weekend and fins out. I bought a new timing chain, and balancer. Got a water pump for the heck of it too. I'm hoping it's just the chain, cause I don't hear the valves when it cranks over, it just acts like it wants to start, but the timing is way off..

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Scott, 20
Dallas, 70 Chevelle Malibu
 

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I hate to bring bad news, but you better rip off the oil pan and check the internals. The only time I've seen dampers go that bad, that fast, is when the crank has some SERIOUS vibration problems...like a toasted bearing, or broken piston skirt.

I had a 283 that blew the damper in February, which I replaced. It then blew the crank in March.
 
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small blocks are notorious for the nylon cam gear coming apart, be sure to remove and clean out the oil pan of those pieces or you run the chance of starving the oil pump. while you're in there, check a bearing or two,also a new oil pump is a good investment,also what about the rear main seal???
 

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Everybody's right and if anyone has a older motor and they don't know how long they have left with their timing chain ratchet has the right idea. But its even easier than that. To check timing slop just grab the crank pulley and turn the motor by hand back and forth. The distance it moves easily back and forth is the slop. You'll know because its easy to turn the motor over when your not turning the cam. You could even use the timing marks on the timing tab to see how many degrees of slop you have. Its a simple check that you don't need any tools for except your hands and about 30 seconds. Obviously too much slop isn't speedr8413's problem but its a nice tip to know especially if your looking to buy a used motor.
 
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