509 on block
 

Hey Guys have a few 350's and cleaned one up tongiht to get it ready for the machine shop. Its the common 3970010 and has the .10 and .20 on the timing cover which some say has high nickel, but nobody knows for sure. Anyway it also has the 509 in between on the timing cover, is this anything significant to the block or make it special in anyway? Doesn't really matter much I think I will use it if it checks out ok, just think all the history on the small block casting stuff is cool. Thanks for any info guys.

Moved to Basics forum.

I recently scrapped one of these blocks. I`ve seen the 509 on many blocks, but they were all the same 010 casting number and they too had the 10 20 on them. I don`t think it means anything other than perhaps heavy duty block.

The 509 is probably an internal Foundry mold/cast #.
The 010, 020 is Tin & Nickle content.>> http://www.chevytech.info/2c42o8.html hopefully it was actually added. :D