Cam chain tolerance

[Troyskie]

G'day fellas,
As the 1200 is in bits I wanted to see if the cam chain needed replacement.
She only has 38K miles & I've never had to replace a cam chain on any of my other FJ's before.

Is there a way to measure the cam chain, i.e. count x links and measure, without splitting the cases?

Or, how do I work out if the cam chain is stretched?

The service manual I have simply say, 'if stretched, replace' but don't tell me what stretched is.

The top end came off as she was low on compression and smokey. It seemed to run nicely aside from that.

Troyskie

[racerrad8]

G'day fellas,
As the 1200 is in bits I wanted to see if the cam chain needed replacement.
She only has 38K miles & I've never had to replace a cam chain on any of my other FJ's before.

Is there a way to measure the cam chain, i.e. count x links and measure, without splitting the cases?

Or, how do I work out if the cam chain is stretched?

The service manual I have simply say, 'if stretched, replace' but don't tell me what stretched is.

The top end came off as she was low on compression and smokey. It seemed to run nicely aside from that.

Troyskie

Troy,

There really is no way to check chain stretch without comparing to a new chain. I can try and measure a specified length of a series of links if you want to try and measure. The automatic adjuster is able to compensate for the chain stretch over time, but the cams will become more & more retarded in timing.

You should install adjustable timing gears to compensate for the timing chain stretch.

The starter chain is going to be the chain with the most amount of stretch and the usually source of the "noise" coming form the engine. That chain does not have a tensioning mechanism and just flops around in there resulting in the chain "rattle".

Since neither chain can be replaced without splitting the cases, I would say you are better off installing the adjustable timing gears and letting it run.

Randy - RPM

[Troyskie]

Thanks Randy. I'll cross my fingers and just go with how it is. I've only taken the top end off to do the valves, pistons, rings.
Cheers,
Troyskie