I am going to look at one tomorrow and can't remember. 4.125? The only casting numbers are 509 511 and 817, correct?

4.125
i think you are right on the casting numbers

4.125" is the std. bore for a 400 and the casting #'s are

330817.....400...72-80...2 bolt

3951509....400...70-71...4 bolt

3951509....400...74-80...2 bolt

3951511....400...70-71...4 bolt but replacement blocks was 2-bolt

Some call it rumor, some call it fact, some have better luck than others.

The 817 block is SOFT, stay away from it (let the flames begin, I know there are a few here surviving big power numbers)

The 509 if the reputed 'best of the crop', with the 511 'replacement' 2bolt running a very close second. The 511 and the 509 are noted as having better cylinder wall thickness, and less occourance of significant core shift.

4bolt main 400's have a factual reputation for cracking in the main webs. Putting a bolt in the thinnest portion of the main web was a very BAD idea. Stick with a 2bolt casting for the 400's.

If you even think about a 2bolt and converting to splayed 4bolt, do yourself a favor and buy an aftermarket block. I just picked up my 400 block (for a backup 434) and the total ticket was $1350. Only parts included were cam bearings, block-fill and freeze / oil galley plugs. EVERYTHING else was labor. It makes NO SENSE to dump this kind of $'s into a poor production casting. A aftermarket 4bolt Motown or Dart block will run about $450 more than a totally prepped stock casting, and all you would need is a hone to final size. (I already had the block and the splayed caps so I couldn't resist)

I picked it up today, a 509 standard bore engine. It has these heads
468642.....76-up...350/400
I don't know anything about them, do they flow the same as 441 or 993 heads?


thanks for the help!

[This message has been edited by Daniel (edited September 15, 2005).]

<font face="Arial,Verdana" size="2">Originally posted by Marv Davis:
[B]
The 509 if the reputed 'best of the crop', with the 511 'replacement' 2bolt running a very close second.
B]</font>

You just made my day Marv! I finally got my hands on a 400 block the other day myself, a 511 2 bolt, standard boreshould clean up @ .020. I hadn't been able to find out any information on the 2 bolt, all 511s referenced as being 4 bolt.

Gave $200 for the block and crank. Still a grease bomb, but friend will reimburse me if it doesn't mag good. Soon as the pennys are collected and rolled, my Vic Jr heads will have the home they've been waiting for.

What kind of deal did you score on the 509 Daniel? Sorry to hi-jack your thread, I just got excited to finally read a reference to the 511 2 bolt. Especially a positive one.

Heavychev, I paid $300 for the complete longblock. Its all standard, I took it apart and it looks great, even the timing chain is good. The seller gave me a written guarantee on it. It had been sitting in the corner of his shop for like 10 years. The one thing that really concerns me is, one of the main caps is backwards- you know how all the arrows point one way? Well this one points the opposite. I was there when the guy took the pan off, so it must have came that way from the factory. It had all original gm bearings, gaskets and pistons so I guess they just put it on backwards. I don't know what to do about it. Anyone else see a main like this?