Idler sprocket carrier in sand cast housing

[Daves911L]

I'm putting together an early motor this afternoon, with aluminum case/chainboxes. While timing the cams I noticed that the idler sprocket carrier is rubbing against the back of the chain box on the right hand side. Is there something unique about the idler sprocket arm for these motors? I just grabbed the best looking one out of a box of several, and don't know which one would have originated in this motor. Or could there be a small spacer/wear plate to go in place. Something I've never noticed before. Thanks for any thoughts.

DG

[Walt Fricke]

These should self-center fore and aft, so the chain is what locates this sprocket. If your chain parallelism is way off, maybe that could cause this issue?

[Daves911L]

Walt, thank you for your reply. I double checked the sprocket alignment this evening and all is good. I think I see what is going on, and it is no problem. I have new chains and all new sprockets, and so the idler sprocket is sitting as low as it possibly can due to the short chain path. This puts it close to, but just above the "ledge" along the wall of the chain box. When properly tensioned it stays clear of it. And you are correct that it should "float" with the chain, out a bit from the back of the chain box
Thanks,
DG