Has anyone ever drilled the crank for a pilot bushing? I know Olds cranks were not machined from the factory for the pilot bushing. Wondered if it was possible to do with the crank still in the motor?

 

Its possible, but not easy. drawings available at wildaboutcars.com

 

No. The required concentricity of the pilot bearing hole can only be obtained by putting the crank on a lathe.

Do not confuse this with drilling a CLEARANCE hole when using the conversion bearing for AT cranks. In this case, the conversion bearing is centered in the existing recess in the crank for the torque converter snout. The hole is only to allow clearance for the tip of the MT input shaft where it projects through the conversion bearing and into the space where the factory pilot bearing would have been. Since this hole is only for clearance, concentricity and diameter really don't matter, so people have drilled this hole with the engine in the car. Again, you cannot do this for a factory-style pilot bearing.

 

Look at the following thread:

https://classicoldsmobile.com/forums...tml#post357582

 

i have drilled two cranks while in the engine using a magnetic drill press mounted on the stick flywheel,drilling it for a chevy bushing.many miles including the dragstrip without a problem.

 

I would agree with Joe P's advice. Not only should the pilot bearing be dead center so the input of the transmission won't precess, but the bell housing should be centered, up/down and side to side, as well as in/out going around the hole for the trans. Lakewood and others make offset dowels for the block to get the bell housing aligned perfectly, or within a few thousandths at least. People have gotten away without aligning the bellhousing, and with the pilot bushing only approximately centered, but that is not the right way.

 

Listen to Joe P. and Joe D.--they know what they are talking about. It can be done the "flat rate" way, heck, they make a kit to cut the input shaft of the trans. to make it work, but.............that REALLY isn't the "right" way to do it. Kinda like balancing the rotating assembly in a bottom-end. Do you NEED to do it? Maybe not. Should you do it? Absolutely.