Ok this is what i have done... took a 1979 350 and put a speed density tpi on it. so this older motor does not have a roller cam in it - that means that the distributor gear on the 91 distributor will not work with the cam in the old 350 motor . is this right ??? can any one please tell me what gear i need to get to make the newer distributor work in this older motor? if im putting this in the wrong place to find this out will u please let me know? have gone too far on this to give up but do not want to shell a gear in side of this motor! i don't think that would be good in any way at all . Let's say, hypothetically speaking, if I was reversing this process and going from TPI to carb (old school style) that means that I would have to use the old style HEI distributor with vacuum advance in a roller cam motor. Would they not need to change the gear on the distributor when they went from the new to the old style? If this is correct, then somebody or some company has a gear to let you accomplish this...?...

 

Put your '91 distributor in and stop fretting about it.

Factory roller cam distributor drive teeth are only very slightly harder than flat tappet cam teeth. The factory roller cam distributor gears are "melonized", an anti-wear surface treatment. They are fine running on a flat tappet cam distributor drive teeth.

 

Sorry that im fretting about this but life has all of us on a tight budget and don;t have any money just to take a chance on something that i can avoid before it happens ! I highly appreciate the answer that was given and will go and put it in and get back to work on it . special thanks to FIve7KID !!!!!!!!!