Timing chain stretch

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How much is too much? Is there some value based on the link length?

Here's my Gen Coupe that is know for chain stretch.

chain-slack.jpg


This is another car but shows the whole chain system.

2k-chain-cover-off.jpg
 
What are the specs on deflection? Timing chains are really troublesome these days, regardless of brand but if you don't have any weird noises or timing codes, no need to worry.
 
I had a 1998 Yukon that around 230,000 miles would stumble under hard acceleration and throw a code that worked out to be Random Misfire. This was pre LS engines so it had a distributor driven off the cam. I swapped in a new Cloyes chain and gears and that was the end of that. Truck ran silky smooth again. It was the sloppy stretched out chain causing the distributor to bounce.
Those older Chevy engines did not have any chain tensioners. I'd imagine your engine is a little more forgiving.
 
Originally Posted By: PeterPolyol
What are the specs on deflection? Timing chains are really troublesome these days, regardless of brand but if you don't have any weird noises or timing codes, no need to worry.
I can't find any in the manual. And some early engines (like mine) have had valve damage from too much slack in the original chain.
 
Don't most have hydraulic tensioners that tension the chain up once the engine is running? Some slack with the engine off is meaningless then.
 
I think a lot of the problem is modern oils, I use a high Zinc level oil to help stop pin and bush wear.
 
These things have a ratcheting mechanism in them. The oil pressure just keeps positive tension on the chain to enable the ratcheting action as chain stretches over it's life span and also dampen sub-ratchet-incremental? slack, that is the slack that exists in between ratchet locks that isn't enough to engage the next 'click'. Sometimes the ratchet mechanism fails, sometimes guide wear and chain stretch max the tensioner out.
 
Originally Posted By: kris42
I think a lot of the problem is modern oils, I use a high Zinc level oil to help stop pin and bush wear.

Not the oil but the longer oil change intervales, annual oil changes?, no thanks
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