Finally ready to upgrade my ol' Chevy engine to a new-style Delco P
ermanent-magnet , G
ear reduction (PG) starter motor, replacing an original 10-MT old-style starter. There are several versions of the PG-style motors, including brand-new aftermarket items most of which come from China. (I bought a rebuilt Genuine GM starter motor.)
Remy issued a Technical Service Bulletin in February 2016 regarding the replacement of old 10-MT starters with the new, smaller PG-260 "mini starter" like mine.
Remy Starter Upgrade 10MT (SD300) to PG (PG260) | Remy Auto Parts
One of the things in the service bulletin is that all PG-style starter motors are machined for a 10.1 mm knurl on the starter bolt. This is a larger knurl than the old starters and engines used, which was about 9.7mm (about 3/8").
Therefore, to PROPERLY install a PG-style starter on an older engine block, you need starter bolts with a stepped knurl--the knurl by the threads which fits into the block is the same size as the older starter bolt knurl. The knurl closer to the bolt head, that fits inside the starter housing, is larger.
ARP does NOT list a correct bolt for this application in their catalog.
The ARP 430-3514 "Mini Starter" bolts have a standard non-stepped knurl. They may be correctly sized to go into the engine block, but a PG-style starter will wiggle around on the smaller knurl. The ARP bolts may be correct for other aftermarket mini-starters, but not the PG-series.
GM p/n for the "long" 9/16 hex head, 3/8-16 thread bolts is as shown above in the photos, 12338064.
The p/n for the "short" 9/16 hex head, 3/8-16 thread bolt is 14037733.