Originally Posted by Ski in NC
SAE flywheel housings are standardized. Sort of. Usually bolt circles are per spec, but flywheel faces are often modified for clutches or torque converters. No way to really tell til you get the engine and measure things.
I'd use 1/2" plate to adapt to the gear.
Usually no alignment pins, things are kept centered by pilot bore shoulder on plate. You need a big lathe to cut that, or a mill with a rotary table.
Bolt circles and crank CL are concentric.
A lathe or an easier idea is.
Get some square key stock.
heat it up red and bend to fit the circle.
Red hot this bends and conforms like wet spaghetti
Tweak it so it fits well, weld the ring shut
Center and weld to the steel flat circular plate.
Note this weld circle does not have to be absolute perfection.
What is critically important is lining up the bearing train so everything is inline.
kind of like what I did here but on a larger scale. But does require some skill.
If you could put the motor vertical so flywheel faces straight up, have one side of the plate finished, likely transmission side, with the damper bolted to flywheel and transmission sitting in place on top of the motor, it partially mostly self aligns, then you mark all 4 sides of the circle as far as how far it can slide to the extreme one way then the other the transmission attached to the adapter plate your making onto the bell housing, then take half of that and your centered. You're taking advantage of the play to determine the center.
Before this you have the ring you bent fit to the inside of the motor bell housing circle
So after you marked the plate, unbolt trans and tack weld or braze the ring to the plate.
Then remove plate and weld or braze entire ring. then drill the bolt holes.
Even so, I know it can be done, and harder than I am describing this.
I would rather get one already made, but if I had to do it, I would get it done.