Hi,maybe you can help me out here,I'm familar with older SBC stuff but not the later one piece rear main seal engines
I have a 1990 305 engine in an earlier model body,it's similar to the HO 305 but modified a but more.It's a project car I been putting together.It's time to buy a flywheel and clutch.This will be a 153 tooth flywheel.
I checked around and it appears these HO 305's use a fairly light flywheel,about 16 lbs,is this correct? I always thought a street car should use a heavier wheel. These lighter wheels from after market makers are priced from 80-160 bucks.GM performance offers two 153 tooth wheels,a 16 and 24 pound for about 250 bucks from Summit or Jegs. Being this isn't a race car,the cheaper aftermarket light flywheel is the way to go if a lighter flywheel is ok.
On the clutch,it appears the one piece rear main seal clutch uses a different pressure plate than the typical GM bolt pattern used for many years? The tranny I'm using has the 10 sline shaft rather than the later 26 spline.I was told the 10 spline clutch disc might hit the flywheel bolts cause of the way the later flywheel is machined?
Thanks for any help, Tony

 

IIRC, a same size clutch, whether early or late, should be the same bolt pattern. The fly wheel on the other hand is different. The early style for 2pc rms has a larger bolt pattern, compared to the later 1 pc rms which is a smaller 3.00" pattern. So long as the the clutch disc is the same size as advertised for the flywheel, you should be ok. hope this helps

 

I found that Zoom clutch makes what they call a "Crate Engine" clutch kit.Has a pressure plate for the later flywheel with a 10 spline disc for using earlier GM manual tranny's.The tech rep said the earlier pressure plate will bolt up to a later flywheel,but becasue of the difference in where the two flywheels sit,the clutch fingers will be at the wrong location.Both use the same clutch throwout bearing that Chevy has used forever,according to him anyways.