Noisey valve train - Listeroid 6/1

[Crofter]

Veggie, the 10 to 15 thou may be between the idler and crank gear alone while more or less also exists between the idler and the camshaft gear and the combination of clearances is what allows the parts to separately get a "running go" at each other at the start and end of every power stroke and perhaps separately for each cam lobe event. Xyzer had a formula for the ratio of tooth clearance change per unit of offset on the idler.

[WGB]

Off the topic of backlash, but about the same issue.
How the heck did you guys hear the gear noise?
What sound did you hear?
All I heard was standard Listeroid noise, then the hiss of the exhaust unloaded.

[veggie]

As the engine comes to a stop you can hear two distinct "clacks"
each time a lifter rises and falls. One of those clacks is the
gear lash. A gear with less lash would be much quieter.

Veggie

[Tom Reed]

I believe the clack is caused by the cam lobe moving past tdc on the lifter and the valve spring pushes the cam gears to the opposite side of the lash. My gear train was real noisy until I installed one of XYZER's off set bolts and a bronze cam gear. It's pretty quite now and has almost 1k hours on it.

[Crofter]

I believe the clack is caused by the cam lobe moving past tdc on the lifter and the valve spring pushes the cam gears to the opposite side of the lash. My gear train was real noisy until I installed one of XYZER's off set bolts and a bronze cam gear. It's pretty quite now and has almost 1k hours on it.

I dont know whether the valve springs would have enough energy to accellerate the camshaft away from the crank gear after every lift event (that would likely give a faster cadence clang) but looking at the cams arrangement you can see where it might happen at the lowering of the injector pump plunger which would coincide with the end of the power pulse slap. Just conjecture on my part, but I am sure you are right about it being gear train collision. anyone remember hearing the clang travel down the cars when a train engine changes from pulling to braking and the slack reverses?

This post is an attempt to attach a picture; lets see if it works.

[Tom Reed]

Yes the IP is the more likely culprit here.