[LMSRACER]

Originally Posted by LPI

I have the revision list from 2/69 thru 7/72 which shows most of the changes and updates over the years on these 9799 thru 485 blocks.

The actual material used was Cast Iron - G.M. 232-M

One of the reasons why the main caps break or crack at the dowel pin hole is from switching from factory bolts to ARP/Milodon studs. Studs and 4 bolt mains are not better unless you look at all of the parts and each individual application.

Another note. GM did not use "standard" diameter dowel pins in the main caps.

For those that don't know, He's talking about the 455 Block when he says "9799 thru 485".

Also, for those that don't know, the Pontiac Dowels are 0.3095" and NOT 0.3125" (5/16").