Underdrive Pulley Questions

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Originally Posted by Bebbetufs

I should have thought about the IMS procedure.

How about drilling and tapping a hole in the pulley and then drilling a small matching dimple in the block to accept a set screw? If this is done while the engine is locked at TDC via the flywheel it should be very accurate. Would this be enough to hold the timing during the procedure?

A better solution is to save your OEM pulley, label it, toss it in your spares bin and don't shave off too much of the timing boss. This is what we did and the IMS retrofit was reasonably uneventful. It took an extra 30min or so to re-install the original pulley and align to TDC. Lock it in with the factory pin and we were good to go. Most shade-tree tuners don't think this far ahead and get in trouble when the motor needs internal work.

PPPPPP

[Bebbetufs]

^ +1. Shave as little as possible off the boss. I have had to reinstall the original pulley to adjust the cam timing. It would be an even greater hassle without the boss.

I got a mate to lock the flywheel with a large and strong screwdriver. There are some gaps between the bellhousing and the block where this can be done. Make sure you know which way it will spin when you tighten. That way I was able to properly torque the bolt without the engine turning over.