Timing gear misalignment

[FC-Pilot]

Got a tricky one for you. I am running a gen VI big block timing set and cam on an engine I am building. The cam gear sits out about .030 further forward than the crank gear. This is a rollermaster set with iwis chain, so not a $29.99 cheapie set. I thought about ideas for machining part of the cam gear (not that I have the capability of doing that anyway), but that would screw up the thrust setting with the cam lock plate. There are not shims that can go behind the crank gear is there?

(Now I remember why I like belt drives so much.)

Paul

[Geoff2]

First I would be finding out WHAT is causing the 0.030" discrepancy.

[russxr67]

I’ve had that happen on a few SBF builds with the same sets. On those I’ve just fabbed up an aluminum washer style shim of appropriate thickness to go behind the crank gear.

[Kevin Johnson]

https://www.mscdirect.com/browse/tn/Raw ... shim+stock

A local water-jet shop could whip one out with a few lines of G-code.

[FC-Pilot]

I stumbled across this thread last night after doing a ton of searches. I think this is perfect for what I need. Thanks for the help and ideas guys.

https://www.speed-talk.com/forum/viewtopic.php?t=10649

Paul

[MadBill]

I replied to a similar thread some time ago, saying that I had once been told that the 'cam forward' position was by design, so that chain tension can help keep the cam from drifting forward and affecting ignition timing.
Besides, as long as there's at least thirty thous more distance between the chain link axial openings and the tooth flanks, the chain can center itself.

[gmrocket]

I stumbled across this thread last night after doing a ton of searches. I think this is perfect for what I need. Thanks for the help and ideas guys.

https://www.speed-talk.com/forum/viewtopic.php?t=10649

Paul

Maybe your crank was at its rear most position on the thrust bearing?

Should check it at both forward and rearward Max’s to see where you are at

[FC-Pilot]

I stumbled across this thread last night after doing a ton of searches. I think this is perfect for what I need. Thanks for the help and ideas guys.

https://www.speed-talk.com/forum/viewtopic.php?t=10649

Paul

Maybe your crank was at its rear most position on the thrust bearing?

Should check it at both forward and rearward Max’s to see where you are at

It was all the way forward. Even then the .007 of thrust would not have lined it up. Gonna have to shim it.

Bill, on this BBC I am using a a cam thrust plate and gen 6 timing set so thrust and cam retention is already set.

Paul

[BillK]

Paul,
Is the chain actually misaligned or just the front face of the sprockets ? I remember a thread a while back where the person said the sprockets were not aligned but when you actually put the chain on them it was fine. Also, there are a couple of different timing sets normally for the Gen6 setup. I have never used a rollmaster set but I know on the Cloyes sets you have to make sure and get the correct one. One of them is made for the factory crank trigger wheel and the spacing is different.

Bottom line is you should not have to be putting shims in there to correct a part that is manufactured wrong. Not sure why you guys put up with that crap. I would get a different timing set that fits properly.

[FC-Pilot]

Paul,
Is the chain actually misaligned or just the front face of the sprockets ? I remember a thread a while back where the person said the sprockets were not aligned but when you actually put the chain on them it was fine. Also, there are a couple of different timing sets normally for the Gen6 setup. I have never used a rollmaster set but I know on the Cloyes sets you have to make sure and get the correct one. One of them is made for the factory crank trigger wheel and the spacing is different.

Bottom line is you should not have to be putting shims in there to correct a part that is manufactured wrong. Not sure why you guys put up with that crap. I would get a different timing set that fits properly.

BillK, yes the chain is misaligned. The factory “crank trigger” is set between the balancer and the timing gear, so that is not my issue, but thanks for bringing it up to have me check. I figure the more comments and ideas will also help the next guy down the road that runs into the same issue (and actually checks this stuff). Thanks again for all the thoughts and ideas guys.

Paul