Can someone please school me on the differences between the Bill Mitchell block & the Callies block please? I'm getting ready to pull the trigger on a new block, just wanting to make sure I'm going to buy the best for what I want. Thanx.

I wouldn't buy another BM block unless it was free....Mine had the head deck holes drilled into the water jackets. +20 years of owning and buying Hemi's, and that's never happened, let alone on a brand new block....Called him on it, and he treated me worse than Indy if you can believe that....With service like his, no thanks, been there, done that.

Other than that, the blocks are very similar. I will have to look mine over a little more, but they are very close.

Bill Mitchell is aluminum and Callies is iron. So.. that's a difference. I just bought a BM block, and so far, I don't see anything wrong with it.

What Deck holes are you talking about?

Bill Mitchell partnered on iron ones as well for a while. Not sure of the arraignment, but Zippy is very fluent in the Mopar history of that era. I had one....Now I have a Callies...and one other block. Both in cast iron.

Call (865) 947-0426 Hensley Performance just there the other day. I know Ken and Matt have already had both. The Callies and the BM blocks through the shop lately. Great people to talk to

Funny every small block chevy ever built has the head bolts drilled into the water jackets, never seen it as a deal breaker. A lot of engines have the head bolts drilled into the water jackets, that is what they make teflon pipe sealer for.

I bought a BMP block a year ago. It is one of the first produced in 2021. Machining was good. My machinist did align hone it as one bearing bore was a bit tight. Also took . 005 off the decks. The cylinders were smaller than 4.490, at 4.486 if i recall. The bushed lifterbores were a challenge to get honed to size but that i believe is a good thing, as my lifters are . 9030. Cost about $1,000.00 to get it assembly ready. I didn't consider that out of line given the block comes with sleaved lifter bores that need to be machined to your lifters, and have oil feed holes in them for hydraulic type lifters. Also the bores took time to get brought out to 4.500, which added to the final cost. The block ready for assembly weighs 143 lbs (cheap bathroom scale) and my megablock weighs 148 lbs for a weight savings of 105 lbs.
All in all, so far i am happy with it. I got as far as final assembly before changing directions on the heads. That decision required new( different) pistons which are still on order along with the heads. So far i see it as a good purchase.

That was after they stopped making the iron ones. I had one of the iron ones a while back. Some kind of agreement with Chrysler/Mopar....



That's great if you know about it. BBM was never this way, and we have never had to put sealer on every head deck bolt on a BBM before...So going to the track and block fills with coolant and locks up is not cool.....

Sure. Back then they were know as World or Mopar Performance blocks. The Op was asking about Callies or Bill Mitchel which are current blocks, so I assumed he was asking about the aluminum block since BM hasn't made iron in somewhere like over a decade.

Well, I doubt the service I got could have been any worse when I called them. So if you like dealing with people like that with that kind of money at stake, be my guest. My buddy has one of the BM aluminum blocks....Guess why its not running the last two years.....leaks water into the oil. Ran good the first year or two...

I hear what you're saying and I agree that is sucks to spend a large amount on an item that turns out to be defective and get horrible customer service on top of it. Unfortunately, we don't have too many choices for aluminum hemi blocks and all the available vendor have a poor reputation. I bought my block from a distributor (Todd Marsh) and have been very happy with him. Hopefully, I don't have to deal with BMP directly. So it's a case of playing with fire or not playing at all. We just had two member do builds with the BMP block with no major issues. Perhaps BMP has improved in build quality. I certainly hope so when I go to build mine, when or if, all my other parts finally show up.

Basically the same block one in aluminum one in iron. The Callies block is based off the "megablock" castings that Mitchell/World were making. Not saying World blocks didnt have issues but it seems the BMP stuff seems to be much better machining wise. I had three iron and two aluminum World/BMP blocks and definitely had some issues. But not unusual for this stuff to reuire some work to be perfect. I did have one that required way to much work and the conclusion was drawn that it was possibly a blem deal.