Timing chain jumping a tooth

Not to hijack several other threads where the possibility of this has been mentioned I thought I would ask the forum members for personal experience.

However, I am going to narrow it down a bit. Many factory timing gear sets came with nylon coated teeth. I'm not asking about those.

Has anyone here ever seen a aftermarket double roller timing chain that had actually jumped a tooth?

NOPE. I have seen them break, stretch very loose, ect. but never just simply jump a tooth. I have seen timing belts jump a tooth or two before but not a chain.

I've not seen it with an after market double roller chain. As you said the nylon gear would let it happen. I saw it twice in the early 70s. Both times it was a SBC that was at the end of it's useful life.

Chuck

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cant happen.

I have seen the upper timing chain gear/camshaft bolt come loose and we thought it jumped timing, before we tore into it and discovered the truth.

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cant happen.

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And you say this because?

Chuck

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cant happen.

Click to expand...

And you say this because?

Chuck

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I was thinking the same question Chuck.

This is the engine that came with my Mustang.

Talk about a loose timing chain. And the engine

ran really good even in this condition. Then I got

the engine from Don of OMS and learned what a

Mustang was supposed to drive like. The old engine

had a D1 block, one D2 head and one D3 head. Not

to mention two cylinders were bored 0.040 over, the

other six were 0.030 over.

But it ran really good. Maybe a testament to Ford

engineering. You have a mass of half broken dissimilar

parts and it ran really good.

mike

I have never had one jump. I have never seen one that did. Newer ones with tensioners might be prone to it but I also would be surprised to see a classic double roller jump (and just jump once...)

I have never seen one jump or have heard of one jump. I have been a certified mech-a-neck for almost 30 years

I believe a double roller chain loose enough to jump a tooth would be slapping against the block.

Your collective responses are exactly what I expected. I've seen a few people throw that out as a possibility for a car running badly-and while it would certainly make a car run badly, it is such a remote likelihood for anything other than a nylon coated factory gear with very high mileage, that I thought we might want to discuss this before someone tore the front end off their engine to investigate.

Keep responding if you know something from personal experience-

I think some unscrupulous mechanics tell people crap like this cause they could make a grand or more to replace a timing chain and then a few more bucks to fix the real problem of a bad coil, condensor, points, ignition module or whatever. Then it gets repeated over and over again until people start to believe it.

.

Its easy to tell if a chain has jumped or needs replacing.

1. install a piston stop.

2. rotate the crank 360 degrees in both directions and mark the damper when it stops.

3. measure half way between the marks and draw a line . . this will be true tdc.

4. connect a timing lite and check the timing . . if it fires more than around 40 degrees from tdc, either the chain is stretched beyond belief in which case it needs a new one irregardless of whether it jumped a tooth or not, or the distributor has rotated which can be checked by simply trying to turn it be hand. Or the distributor gear pin has sheared allowing the gear to reposition itself on the shaft.

FYI. When my original busted nylon timing chain jumped, the ignition timing was off by exactly 10 degrees.