It appears the Dart And Bowtie blocks have smaller water passages to the head than the 10237300.( better head gasket seal I spose) Also you can get a Bowtie block with the 6 or 10 bolt timinig cover. One has a 1 piece and the other has a 2 piece rear main. Possibly the one will cool better w the larger water passages in a open cooling system. Maybe that is why mercury used them.

All the parts for a one piece seal block are a little more money. There is alot more two piece stuff out there. If I was starting from scratch I would spend the money and get a two piece dart block. It worth it in the long run. If you shop around you could probably get one for 1800 I bought mine for 1800 with a block kit about a year ago.

GEN 7 BBC is the 8.1.

peace
Hog

Hog....that's what I meant...trying to find out which previous generation parts fit the gen7....crank ?...rods ?...rockers ?...pan ?...etc...

I don't really know the answer . But i think the heads and exhaust ports may be different. If It were me, I would just run the Gen 7 parts and not try to run other gen stuff with it. Unless the part number is the same. Just check part numbers. I would Only Use what Factory built. Like a 300 block on a freshwater motor. Like I said, It looks like the water jackets are bigger by the head than say a Dart or Bowtie block. The 300 block runs 135 water temp and 140 oil temp for the most part. That means Mercury did something right in my book.I guess I answered my own qustion here. Don't basterdise unless you are building a vdrive or some drag car/ boat.

http://www.ebay.com/gds/Big-Block-Ch...1563647/g.html

Decent breakdown of the different mk and gen big blocks. Pretty informative.

I would go with the bowtie block. But talk to your engine builder.

Wannabe

Nevermind. The head gasket restricts the water. Btw. I 'm my engine builder

Btw. If Anyone has replaced a zz502 block with a bowtie block Please speak up! I am "headed" in that direction

Just got my new gen 6 bowtie block delivered to the house last friday. Nice piece and way better than production block i am replacing. I ended up ordering it through Summit Racing because the had free shipping. $1879.87 to my door. Couldnt beat that accounting for shipping savings.