283 Nova Block Questions

Jim Parsons · 05-20-2011, 06:01 PM

Vic,
I have had a few of both the 721’s and standard Chevy II 283 blocks through the years and to the best of my knowledge you are correct on all accounts. Another give away for these blocks is the fully machined main bearing web and obviously small journal size.

Also most of the 721’s were the 10-20 (high nickel /chrome) casting which provided a little more strength and better grain structure. They will typically hone up nicer and hold the wall straightness longer, not Bow Tie quality but next best thing in my mind.

Joe is also correct about the OEM L-79 blocks bringing good $$ to the restoration market as I let one go last year. Wish I still had the one that came in my car new but let it go in our car hauler back in the 70’s, Oh well!

Jim Parsons

05-20-2011, 06:01 PM	#6
Jim Parsons Member Join Date: Feb 2002 Location: Kearney Mo Posts: 197 Likes: 427 Liked 195 Times in 30 Posts	Re: 283 Nova Block Questions Vic, I have had a few of both the 721’s and standard Chevy II 283 blocks through the years and to the best of my knowledge you are correct on all accounts. Another give away for these blocks is the fully machined main bearing web and obviously small journal size. Also most of the 721’s were the 10-20 (high nickel /chrome) casting which provided a little more strength and better grain structure. They will typically hone up nicer and hold the wall straightness longer, not Bow Tie quality but next best thing in my mind. Joe is also correct about the OEM L-79 blocks bringing good $$ to the restoration market as I let one go last year. Wish I still had the one that came in my car new but let it go in our car hauler back in the 70’s, Oh well! Jim Parsons