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Old 04-09-2004, 07:29 PM
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timing chain stretched

Hello
I posted a few days ago about my timing having to be so advanced. I received a lot of great reply's thank you. I took the advice and tore it down to the chain. I put a breaker bar on the crank and turned back and forth and watched for movement in the chain. There is a little bit of slack before both gears move at the same time. Is there supposed to be a little slop? Also it seems like once the gears start turning together that there is slack from the crank to the rotor before the rotor starts turning, Is that supposed to be there? I would just hate to get it back together again and have the same problem. I know we will all make mistakes but some backs can only take so much. One more thing that bugs me is that there is two timing marks on the crank timing gear, one is closer to the tooth that is the one I used. I hope I'm not asking to much. Thanks again
Ron

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Old 04-09-2004, 07:36 PM
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A new chain and sprockets should have little to no slack. In fact it should be slightly difficult to get the cam gear on with the chain. The other slack you are feeling is probably distributor cam gear wear. Unless you replace the camshaft and distributor gear there is little you can do about it. personally unless it was excessive I would not worry about it. You could however replace the distributor gear, that would be the least expensive.

Vince
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Old 04-09-2004, 10:32 PM
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As for the crank gear marks, I would use the outer mark, If you look closely, there may be three inner marks, which are for advancing, retarding, and "straight up".
In your case, however, I would spring for a new set and not worry about it.
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Old 04-09-2004, 11:34 PM
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Rotate the engine to where one side of the chain is tight, and then measure the sloppy side. I wouldn't worry with anything under about 3/8" of movement, but about a 1/4" would be better. Too much slack will throw off your cam timing, but would not change while the engine was running since the cam is being "pulled" along by the chain. Also even a very loose chain would be only worth about 4 degrees of variation. And last, even though your valve events would be off a little, the engine would still prefer to fire at the normal amount of crank advance.
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Old 04-10-2004, 07:32 AM
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Friggin put a new chain on man!!!!!!!! I had a 302 in my car that had about 80,000 miles on it and the guy that owned it before thrashed that *****. The chain was so loose that it freakin skipped a tooth, locked up, broke, and when the engine kept spinning the pistons banged all againt the valves and tore it up. On top of that something tore the hell out the cylinder wall. So now i have a 351W. I'm serious tho, i wouldnt risk it cause your 5 minutes away from having that one off and another few minutes from having a new one on. Its a cheap replacement, 30 buck for a new stock or upgrade to a double roller for like 60. Ideally the one without any stretch would be a geared set but those can get kinda high if you dont want to spend a whole lot of money. If yall wanna ream me for suggesting replacing it fine, but I know i would never take a chance after what happened to my motor.
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Old 04-10-2004, 09:00 AM
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replacing

Thanks
I'm definately going to replace the double roller thats on there. I'm just surprised it needs it already with such low mileage. I did a slack test on it to see if I also have problems elsewhere. It seems the slack in the chain is equal to 4 degrees while turning the crank before the cam starts to turn, then another 3 degrees before the rotor starts to turn. The distributor was just bought rebuilt and the cam has maybe 100 miles on it. I checked my valves also and they are closed at top dead center. If your chain can only throw you off maybe 4 degrees if it's stretched then this is not my problem because I was running fine with 40 degrees initial advane. I'm looking for at the most 14 degrees initial. I don't think just 4 degrees will solve this problem. I haven't got it all figured out yet, you all have been a big help. Happy Easter
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