Pilot shaft diameter

circlepilot said

Question: The pilot shaft of my A833 is measuring .750, however I can insert a .825 (.075 difference) piece of bar stock in the pilot shaft hole in the crankshaft. The crank was originally used with a 904. I had the crankshaft register modified to accept a larger torque converter, (I was going to go back with a 904 set up but elected to go manual) the pilot hole for a manual transmission wasn't touched. This is a 1965 slant 6 build. Do I need a bushing? or am I reading too much into it. A bushing to reduce the pilot hole from .825 to .750 would be an awfully thin bushing.
Norm

Click to expand...

Many times the pilot bore is not finished to final size on engines that were originally equipped with an automatic transmission, and it sounds like yours isn't. A bushing like you describe would have a wall thickness of .0375- I doubt you would even be able to install it without deforming or distorting the bushing.
Since you have already had the crank pocket enlarged to later LA dimensions, I would do as AJ recommended and use the later Dakota bearing which installs into the convertor pocket.
More Information for TIMKEN FC69907
Confirm the depth of the pilot hole, though. Even though it won't be used for a bushing, it still needs to be deep enough to clear the transmission input shaft. It's easy enough to drill it a little deeper if needed, since it's no longer being used to center a bushing it becomes a non-critical dimension- you can even do it with a hand drill if you have an assembled motor. I've never been a fan of sawing off the input shaft, even though it's a relatively common quick fix.