Thread: out with old....in with the 400...

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Originally Posted by tim_bo16

the 509 casting has high nickel content. i have 2.

Hey Tim, I once weighed the two blocks in question and I found the 817 to be 10-20 lbs heavier, I would recheck it if I were you. My machinist also verified that the 817 block was harder to machine.

Be that as it may, the new Dart block is the way to go for big power if you can afford it.

Originally Posted by TyphoonZR

Hey Tim, I once weighed the two blocks in question and I found the 817 to be 10-20 lbs heavier, I would recheck it if I were you. My machinist also verified that the 817 block was harder to machine.

Be that as it may, the new Dart block is the way to go for big power if you can afford it.

No need to recheck....The 509 block is on average 11-13 pounds lighter than it's counterparts. Why? because it does have 13-15% more nickel in the casting. Therefore it was lightened by GM for what ever reasons the myths out there state. Then again, you don't want the 509's? Ship them to me! By the way, in the two years (86-87) I had the pleasure to work with Bill mitchell, he was the one that pointed it out to me. I've never had any failures with that block (two bolt 509) but a few with 511 and 817. Lucky? Maybe, but I'll take it.