11 inch clutch in a E body

[gkring]

I am putting a clutch in for a friend in his recently aquired numbers matching 70 challenger 440 6 pack car. First go round we got a misboxed clutch disc with a 23 spline instead of the 18 spline. Boxed it back up and sent it in. After a week the replacement comes and everything looks great. Go to put in the pressure plate and the bolts don't line up. It has a 11 inch 142 tooth flywheel! Didn't even think to check that the first time since the block and tranny are numbers matching. Don't you have to have an 11 inch bellhousing as well so the starter lines up right? The car was running and driving condition. Is there a reason for a previous owner to go 11 inch? Maybe better holding power at the expense of some floor clearance with the 11 inch bellhousing. Also the flywheel does not have any noticeable external weight. If the internals of this motor are original will it have an externally balanced flywheel as well with noticeable weight?

[Chryco Psycho]

after 40 years there could be a bunch of reasons you have a different set up in there , if the engine was rebuilt it may be internally balanced or it could be the wrong flywheel / Balance for the engine . the 11" disc is the same for the 10.98 " 130 tooth system or the 11" 143 tooth , just the pressure plate is different , there is no reason what you have will not work as long as the starter lines up . but there are new flywheels & belhousing available if you want to swap to the the 130 tooth system