I'm glad that Ted has jumped in here, re the "I almost twisted it off" remark, re the main bearings torque!.. Hopefully it's not too late!  Many 312 blocks have been damaged or ruined by "over tightening" the main caps..  Good luck.. I believe it was the early 1956 Manuals that had for some unknown reason, a much higher torque listed for the 312 blocks than for the 272-292 blocks..    


Paul

The ARP rod bolt set #154-6004 is the replacement ARP bolt set for the 312 rods.  That particular bolt kit will fit the ECZ, C1TE, and C2AE rods.  Be aware that installing new bolts in the rods will require resizing the connecting rod big ends.
 
Be careful of the torque values for the 312 main bolts in some of the older repair manuals.  They were listed as being too high.  Use the torque value for the 272/292 engines which have the same diameter main bolts.

Lorena, Texas (South of Waco)

I'm looking for Main cap bolts, Piston Rod end cap bolts and head bolts. In reassembling the crank, I almost twisted it off before reaching the required torque. Thanks for advice about John Mummert. Will place an order this week.

What bolts are you referring to specifically?  Main cap bolts, flywheel bolts, damper bolt, head bolts?  Arp has grade 8 bolts available for all those applications.  You don't need anything more than grade 8 for a street engine.  Click on "links" above, and click on John Mummert's site, and check out his listing for all those bolts.  Joe-JDC

JDC

I started reassembling my 312 engine. I realized (in time) I need to replace the crank bolts. I also figured I need the head bolts before something breaks. Where can I find aviation grade bolts for both applications?