I'd like to share with the list the following comments from George Riehl on the non- HP vs. HP stamped blocks. <Hi Bob; You are correct in the way the Chrysler blocks are cast. All 413 blocks, and others, are cast out of the same material with high chrome and nickel content. More than the other car manufacturers blocks & heads contain. Blocks and heads coming out of the foundry are cooled then reheated for stress relief. Then sent for the initial machining. They are checked for sand holes, discarded if any, then final machining and checked again. Any blocks or heads not up to par are sent back to the foundry for remelt. When blocks and heads are found to be perfect, after machining, some are destined for the "premium" line. Generally for high performance, marine and industrial use. From what I have been told by some of the "old timers", is that on the premium engines, final machining is done with "new" tooling to keep close tolerances. "Used" tooling is the used on non premium blocks. After all machining is done, the blocks & heads are sent to the assembly line. The 300 engines, Pistons, bearings, crank, etc. are carefully assembled. All of the high perf. engines then get a precise balance job. I have been told, plus or minus 2 grams, other engines get as much as 20 gram balance. With the high performance engines, they get a flame hardened forged crankshaft to .060. This is what makes a H.P. engine along with the camshaft. N.Yers. and Imps do not get these engines and their cranks are not hardened. After the precise machining, crank, camshaft, etc., then the "H P" is stamped onto the block along with the date of engine assembly. All 413 blocks have the same casting numbers along with the various shift codes when they were cast. Exception to that rule is the "motor home" blocks. They are cast special because of the extra cooling passages cast into them and also the heads. Motor home blocks and heads should never be mixed with regular engine components. But their cranks are hardened Other non premium blocks will have the "diamond", "maltese cross" and other stampings associated with "under sizes" incorporated into the blocks. Re: undersize crank, oversize rod bearings, oversize lifter bores, and sometimes oversized main bearing bores. On GM engines, one can find "shims" under the main bearing caps because of oversize line boring. Never will one find these marks on a premium "Chrysler" block. All 413 blocks are not the same. That goes for all the other "H.P." engines that come out of the Chrysler foundry and machine shops, 318, 340, 360, etc. In all of my years, Chrysler builds the best engines. George Riehl> Bob J [Non-text portions of this message have been removed] To send a message to this group, send an email to: Chrysler300@xxxxxxxxxxxxxxx For list server instructions, go to http://www.chrysler300club.com/yahoolist/inst.htm Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Chrysler300/ <*> To unsubscribe from this group, send an email to: Chrysler300-unsubscribe@xxxxxxxxxxxxxxx <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/