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Timing Chain - Slackend

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G

gonzo

Jedi Knight
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Now with the crankshaft nut, pulley and timing cover removed, the timing chain mechanism to this AH 3000 BJ-7 could be assessed. The Timing Chain Tensioner is riding up aginst the chain and chain is taunt -this is good. However, there's some chain slacking on the opposite side nearest the Dampner. Just how much chain deflection is allowed on the Dampner side? Deflection is about 1/2 to 3/4 inch.

Engine was running great prior to demantle; there's no deviation on timing.

Is there some allowable timing chain deflection or slack on the dampner side or should it be tight. Took some pics but first I need to learn how to post them.


Thanks, GONZO
 
The cam timing will retard as the chain stretches, so a gradual loss of performance over the life of the engine. You would need a dial gauge to measure it. Usually the engine performance drops gradually enough that you wouldn't know it. You do run the risk of the tensioner foot coming of the housing and wedging into the chain perhaps causing a catastrophic failure. I've seen the chain stretch that far but not break.
 
Jumped to conclusions on condition of timing chain. Turned engine in direction of rotation and timing chain tighten up. No slack. Removed original TC tensioner and although the elastomer, bumper, portion is in excellent shape, the shaft is worn. The tension body seems to be in good shape too. The original 50+ year old tensioner will be replaced with a Moss ROLO unit. And although they function in much the same way, I prefer the original's design and look.

Thinking of taking the original TC tensioner to a specialty automotive machine shop to see if it's restorable.

BTW, bolt-heads for the tensioner are safety wire prepared but they also have locktabs - sort of a belt and suspenders set-up. Not skilled at safety wiring, so the labtab with be used.

GONZO
 
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