I need to buy a new flywheel for my 350 Olds engine (1972) so I can install a TREMEC 5-speed. The flywheel manufacturers offer both internal- and external-balance flywheels, but I don't know which type I need. When I ask them which I need, I get doublespeak which makes me think they don't know either. The engine is mostly stock and originally had an automatic trans. Can anyone here tell me which type this engine requires?

 

external balance
You also need to drill the crank for a pilot bearing
Gene

 

You can also try the adapter bearing. Knock on wood it holding up so far in mine.



Crankshaft Pilot Bearing Conversion Auto Crank
Stick shift pilot bearing adapter. A new solution to an old problem. Convert a GM automatic transmission crankshaft to a manual shift crank without taking the crank out of the block. Knurled for a sure fit with self alignment for a perfect fit and smooth running and shifting. Requires modest shortening of input shaft with common tools. Also for engines that are using a midplate resulting in the transmission being moved rearward and not engaging the stock pilot bearing far enough. Fits Oldsmobile 260-455, Buick 350-455, Cadillac 400-500, Pontiac 326-455, and Chevrolet 305-502.
$42.00

 

That adapter bearing is what I use, I also drill the crank end so the input shaft will not have to be cut. I use a hand drill and drill the center until it is the size a bit bigger than the input shaft.
Gene

 

"Internal" and "external" balance are Chevy terms that do not apply to Oldsmobiles unless you are doing custom parts swapping and balancing. There are only two different Olds flywheels, the 64-67 style and the 68-90 style. The difference is in the crank flange bolt pattern.

 

Thanks. Yes I've got my bearing and have drilled the crank for clearance.
The aftermarket manufacturers do offer flywheels for both internal and external balance Olds engines, so I am thinking the internal-balance types are for custom-built engines that are internally balanced.