400 Sbc

I dropped my block at the shop a couple days ago. Got a call from them saying the walls were a bit pitted and I would need to go .060 over to clean then up. Any thoughts on going that far with the 400? I't a 511 4 bolt block. I asked him and he said it would be ok as long as my cooling system was good. Just asking for opinions. Thanks.


Register now (free) or login to remove ads

We ran a .060 over 400 some years ago and I would highly recommend you have the bores sonic checked to assure the thickness. It`s said that 4 bolt 400 blocks aren`t as thick casted as the 2 bolt blocks were, but I`m not sure if this has anything to do with the bore thickness. 400`s are known to crack at the steam holes which no other small block has, so if in doubt have the steam holes closest to the head bolts king pinned.

I've run them at .060" over with no problems, but I always did a short fill block fill to help stabilize the cylinder walls. FYI, you do realize that the 4-bolt 400 is weaker than the 2-bolt, right? Those outer bolts on the 400 4-bolt are drilled into the weakest spot in the main web area, making it even weaker. Just general info, if it is all you have run it till it pukes.

Being .060" over won't make it run hot even with the block fill. That's an old wives tail originating from people putting in a fresh motor and hooking it up to the same tired old cooling system.

I prefer to build 377's with the 4-bolt block as I feel that the shorter stroke crank puts less load into the main bearing bulkheads in the block, but I can't prove this, it's just a theory(others share it though too)

I don't use any 400 block at any overbore without block filler.

I was aware that the 2 bolt is stronger, thats why I mentioned it. I wondered if it would have anything to do with the overbore. What actually is "filling the block"? I have heard of it but have no idea what the process is or what it accomplishes.

Block Filler is like cement for blocks. for a street engine it uses a street fill, a fill only to the freeze plugs. This makes the bottom of the block alot stronger than a non filled block.

You are filling the lower third of the water jacket around the cylinders with a cement-like filler to stabilize and strengthen the block. This filler is usually some form of hydraulic cement (calcium hemihydrate), some have iron filings mixed in to help match the expansion rate of cast iron.