Is cam timing changed or effected by new chains?
 

Anyone know whether new chains, due to their break in period (or other), effect the cam timing?

Thanks

the chain tensioner should deal with this automatically


chain should be tensioned, that's all.. if the chain get's stretched( over time ) then yes , that could mess up your timing if it stretches a lot..)

but not during break in

Yes, but its all relative. FYI: The cam timing does not stay static when the engine is running. At low RPM or idle when the chains have the least tension, the cam timing becomes a bit advanced and as RPM's increase the timing gradually retards a bit. Thus the 'timing range' and the suggestion to time in the middle. As long as both chains were tensioned equally and cams timed equally, then as the chains/gears break-in the timing on both cams will equally change. The chains/gears will wear, but since timing is not static, you really cant compensate for it and it wont be noticible by seat of the pants for sure, possibly with a dial gauge. Don't loose sleep over it.

BTW: When you timed the cams, did you notice for each revolution the timing changed a bit, then after a few more revs its back to where you initally measured it? This is due to the minute differences in the chain links and gears. So, if you really want to get picky with the cam timing, mark a link and corresponding sprocket tooth and measure/set cam timing only when these meet....for the obsessive complusive. The whole point is cam timing is not a perfect science. Tension the chains equally, set the cams as equally as you can, button it up and enjoy.

OK, so the tensioners (out of the box), are already calibrated, but if during cam timing setting (the rebuild book), I'm supposed to use the mechanical tensioner to take the "slop" on the right chain(I still don't know how to identify the term "slop" ),....

....... but since this is keeping the chain stiff for the cam timing, will not the regular tensioner put a slightly different force on the arm when it is put in place of the mechanical one?

Thus the cam timing meter readings might then differ.

Also, when setting the came timing with the mechanical tensioner on the right chain (rebuild book), I have noticed if I change the screw settings up or down, the dial meter will move, will not this happen when installing a regular tensioner, changing the dial reading?

What's driving me crazy, is that there seems to be only one dowel pin hole on the right side cam sprocket wihich leaves me at nearly the 3.0mm dial reading consistently (the range for the E is 3.0-3.3). But I can slightly back the screw down on the mechanical tensioner and bring the reading to about 3.1) Tightest, and the dial will move to 2.9.

the left side cam constently moves to the 3.15 range.

I re-did the torque on the cam nut on the left cam, and was able to fix the reading at 3.15, right in the middle.

I'm still not fully confident on chain tension, even afte going through numerous search posts here The only thing I can say is that the current tensions on the chains, they definitely are not so sloppy that they would come close to mvoing off the rails. I can pull them up about 1/4 in. max off the chain rail then they snap back.

Before you go through the trouble of adjusting your cams heavily oil and cycle the chains and sprokets. When dry chain bushings are lubricated it can shorten the chain length enough to advance the cam timing.

If you have a fairly dry chain with differing amounts of pre-lube distributed among the bushings its one of the reasons why cam timing might change every few rotations of the crank.

At almost a thousandth of an inch a link you can do the math to see why new or degreased chains should be proberly lubed before one attempts to adjust cam timing.

HGP, on pressure fed tensioners the oil pressure puts more tension on the chain and the oil and valves in the tensioner makes it VERY difficult to push the tensioner piston back in under normal circumstances.

When its full of air and has no oil pressure the tensioner springs are hard pressed to keep the chains in check.

That's one of the reasons why there is a range - this is not an exact science. As long as you are within the range, you're fine...

-Wayne

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I want(ed) it as accurate as possible (as the valve adjustment must be), and fortunately after the final torqueing of both the L and R cams today, both are hitting right in the middle. Additionally, I'm seeing both the intake opening and exhaust closing on both sides, they look to be very accurate.

(I took one of the old chain tensioners, which is in good condition, and compared (measured) the heights of the new tensioners, upon address of the arms, and they are about the same spread.)

You can probably change cam timing by as much as +/- 3 degrees and never know the difference, maybe much more.