finally picked up the 400 block. this will be the foundation for my 512 project if it checks out ok. cast in 12-6-71 with 3614230-5. what does the -5 stand for? the bores measure standard with very little to no wear.

Bad news, this one is not the heavy main web cold weather casting. All the "230" blocks cast after 10/10/71 have the standard main webs.

That looks to be cast too late to be a heavy main web block, see attached. I believe the -5 means the core had 5 repairs (common).
But if the cylinder wall thickness checks good (sonic check), it should be a good block to start with.

i did'nt think it was. the heavy web castings were cast between apr and oct of 71, but is this still a good candidate for a 700+hp 512?

Any block is subject to core shift which is the enemy, only way to know for sure is to have it sonic checked.

the webbing in this block does look thick like the pic you posted and the casting numbers are large. can you explain the casting core repairs to get a -5?

So aside from the obvious sonic check/core shift numbers. It's still a good candidate stock block to use.

Not THEE very best (which would be a thick web 230 casting), but probably the 2nd best in my opinion...

thats good to hear.

heres a few pics.

another

one more

That doesn't look like the thick web block.

It looks like a standard one to me, and it could still be a good candidate.

ok, i did look at the webbing on both sides and the mains are thicker than the webbing on both sides if that meens anything. about .155" each side.

as far as the -5, I believe that is the core box number that it was poured in.

i'd like to find an article about the core # to read so i can understand this better.

The main webbing is important but equally important are the thickness of the thrust side ribbing in terms of how well the block was cast. This one was a -2

This 230 I used for my 517 was about average in terms of the 230 main webbing but it was an exceptionally cleanly cast block with very strong ribbing and a very straight cam bore. of the I don't know how many B/RB's I've built over the years this one jsut fell together and turned super smooth. Expert Machining of the block and crank go a long way in terms of the motor not fighting itself....the webbing is a key factor but even the worst 400's I've seen are still thicker inthe main webs than nearly all 440's.

I've seen several thick web blocks that had bore thrust sides so thin they needed sleeves to even go +.030. And some may have horrific cam core shift. Webbing is important but to me it's not the single most important factor in block selection.

thanks for this info guys. after reading the 440source article on engine blocks i do not have the cold weather block for sure. no mistaking it from a standard 400 block.