Caution, if you drill the crank too deep it's possible to break into an oil passage.
There is a Brewer's drawing out there which believe is shorter on the 2.225" depth than what I came up with on an auto crank I have.
The hole depth is plenty deep but the bushing diameter is unfinished..........
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A mag drill can do the job but I think I'd bolt a stout plate across the block to attach it to.
IMO, if you go to the bearing make sure you dial in the bell.
Yep: I remember the Dodge dealer installing a 4 speed behind a 440 in a truck and hitting oil in the crankshaft as well.
I used to think all those 4 speeds swapped into Chevies were junk with their cut inputs, I wish I could go back and buy them all now.
The last stroker Hemi I put together didn't have the pilot drilled deep enough. I left the bellhousing on the engine made the measurement with a caliper and loped off the input about 1/4" as well. Easy peasy. I zipcut mine and dressed it with a hand grinder, 5 minute job after measuring.
This is the easiest way. You are getting some complicated advice about drilling the crank that isn’t necessary and might ruin your crankshaft.
I gave you the short version of my story, here’s the long version.
I swapped my car from 318 auto to 413 4 speed in about 1985. Believe it or not, seems like parts were harder to find then (no internet.)
The hole in the 413 crank was drilled but not finished. It was not only undersized but ran out about .015” IIRC. I made an eccentric bushing on a lathe, but still only got it to run within about.007”
I installed it and ran it like that until 2020.
I had a couple of transmissions in and out multiple times over the years for road / track use.
When I rebuilt the motor in 2020 I had two issues I wanted to address in this area:
1. a high rpm vibration, that I believe was caused buy the bearing runout, since the clutch disk runs on that shaft.
2. Since this was an automatic car and all of my parts came from who knows where, I could barely get the trans in and out. I had to remove the upper tail shaft bolts and grind a little groove in the bellhousing for clearance. In other words the trans is a little too long.
So buy cutting a bit off the shaft (I’d have to go through my notes to see how much) it definitely helps no 2.
I indicated the snout hole in the crank at .001”, much better than the bushing hole. The vibration is gone so I’m calling no 1 fixed as well (this is subjective since it was a slight vibration .)
