[pontiacman63383]

So I'm finally going to back together with my drivetrain. Only took 9 years lol. anyways I'm converting it over to a manual from auto. I've got just about everything I need but I just want to verify some info. From what I've researched almost all the factory clutchs would have been 10.5" with the exception of some older 455 engines that used an 11". I know that the aftermarket flywheels came drilled for 10.5 and 11". Everything I got for this car is used. My question is does anyone know the measurement for the bolt pattern for the 10.5"or 11"? My flywheel only has one bolt pattern so I know its not aftermarket but since its used I really want to make sure that I don't have the oddball 11" flywheel from an older 455. Thanks guys.

[Scott Thelander]

10.5" pressure plate bolt pattern is about 1"+ from the edge
11" is about 5/8 from the edge ....
also there should still be a bevel on the edge of an original flywheel after turning..
clearance the crank bolt heads to the clutch disc springs b4 assembly ...

[north]

I’ve never seen a flywheel drilled for just 11”. Seems like 10 3/8” alone or both.

[pontiacman63383]

Thanks for the info guys. I figured it was a 10.5 bolt pattern and after measuring it with scotts info it was confirmed. I haven't seen one drilles just for 11" either but reading online a few people said they did so i just wanted to be sure before ordering.