So I’ve posted looking for a 330 flywheel but have a question..... my m-20 Muncie came w a flywheel for a 67 400 Pontiac The bolts holes are the same and I counted (twice) 166 teeth

it also appears to be same diameter as the flexplate on my 330. I do notice the center bore is larger The 400 Pontiac flywheel has about a 2.75 center bore. And the 330 has about a 2.50 center bore.

im just curious for my own knowledge. Are flywheels bore centric?

ive read on here that olds engines are externally balanced but I see the at hays had a listing for internal and external balanced flywheels was curious about what kind of application would be the internal balanced

fwiw. I can also tell you that a 100k mike plus used Muncie shifts through gears waaay way better than my brand new tko500

Our tko you have to slap hard to get out of reverse no matter what. Tremec says. ..... yeah. So?....

 

Absolutely! There is no way for the flywheel to be sufficiently concentric if you rely on the bolts alone. Get the right flywheel.

 

400 Pontiac is externally balanced. Even if you could bolt the flywheel up it would cause a vibration.

 

absolutely. I plan to. I just started looking at the Pontiac one so I could put it on Craigslist ..
I noticed it was a 6 bolt flange and then I started wondering. And measuring. I was pretty sure it was unusable when I saw the center bore difference.

I always wonder w a lot of gm stuff —or I guess I assume—- that they do stuff on purpose. Like the tooth count or diameter. Sure the flywheel is application specific but maybe that allows the same clutch pack or the same gear on the starter.

I’m gonna read up on the internal vs external balance thing it’s just interesting to me. We’ve got a 259 studebaker and it just has a steel disc on the front of crank where the gm harmonic balancer would be

 

Olds motors are externally balanced also. That doesn't mean that the balance weight on a Pontiac flywheel is anywhere close to that of an Olds. Given the different stroke and reciprocating mass, you can pretty much guarantee that they are not the same.

 

WOW, I was going through things to get rid off ( were 2/3 done downsizing to a smaller home) and set the 330 flywheel by the re-cycle. It came off my 64 F-85. I put it back in the garage if you cannot locate one. Joe the 330-400E and 425 have the same bolt pattern right?

 

OPP's this is for an automatic, sorry.

 

Correct. All 64-67 interchange.