Ive been researching this for a while and have gotten a million different answers so now im confused on which one is right. I have a 69 cutlass that im swapping a 4 speed into. It has a 403 engine that has been rebuilt, blueprinted and balanced. Do i need an internal or external balance flywheel? The flywheel i was planning on going with is the centerforce 700500 but it doesnt say how its balanced. Is it ok to just bolt on any flywheel and go?

 

You're going to have an issue bolting up a 4 speed to a 403 that was never designed to have a manual trans behind it unless you either installed a crank from a 350 that came with a stick, or you had the crank modified.
All (modern...1964-1990) Olds V8 engines are externally balanced from the factory.

 

You need to find out who balanced it and with what flywheel or flexplate. As Randy said all Olds are external, so they needed something bolted to the end, unless it was modified to go internal.
I wiped out three engines on the dyno a few years ago, all because my former dyno guy said he "balanced" my dyno flywheel to the same imbalance as a stock one. He didn't, and it cost ME a lot of money. One reason why I haven't used him in over two years now.
Good luck.

 

I've got a 403 with a 4 speed so you should be fine there, it will work.

 

the 403 in my regency has the pilot hole ready to accept the bearing. 2 versions?

anyways, if olds is 100% external, if should have balance on both ends, you can theoretically put the rotational balance on one end, but that will stress the mains along the crank center line.

surely if someone blueprinted it, they ran it on an accubalance (or equiv) to at least a flexplate and if they did, its a simple matter to impart the imbalance factor to a flywheel....for a machine shop that does in fact do balancing acts....

 

my T/A 403 has the ball stud boss and the crank is ready for a bushing, but theres no groove cut for a snap ring..is it a Pontiac "equipped" thing...

 

I doubt it's just a Pontiac thing, gm pumped out so many 403s for so many applications that I find it unlikely they changed machining just for the T/A. Every 403 crank I've ever seen would accept a pilot bushing.

 

but there was no stick 403's, right?

my 75 455 has no provisions at all..just kinda wierd

 

Yes your right to my knowledge there were never any 403s with a manual.

 

maybe they where intending to make it..still wierd its ready and none where built..prob for the firebirds if i where to guess

 

Of note, when I yanked the thm400 out of my regency earlier this year, the converter had an extra large piece (or so it seemed) welded on the front that went into the pilot hole, I know autos generally have some sort of locating button and corresponding crank hole but this was overtly large. hard to know what they were thinking, all the engineers are now dead or drooling....

 

I've never really put much thought into it but now I'm curious as well. It could have been since the 403 was being used in makes other than olds they did that so each manufacturer had the option to run a 4 speed.