So can someone clearly define a Siamese block for us? I googled it and am still confused because the photos used to illustrate the difference look to me to be the same thing sometimes.
In the photos on gnttype.org, the Siamese blocks appear to have two coolant passages along side each other above and between each cylinder. Is this Siamese?
When I Googled the info, the definition of Siamese is cylinder bores without coolant passages between them. Is this Siamese?
When I look at the photos above, I see coolant passages along side each other (round and square) with steam holes between each bore. Is this Siamese?
Can someone clearly define what a Siamese or not Siamese stage block look like. Also, are the steam holes desirable or are non desirable for a serious performance build engine?
I believe this statement to be true as Smokey Unick used Siamese cylindered 350 small block Chevy blocks to bore and stroke to 468 cubic inch.
With no coolant passages between the cylinders, the engine could be bored larger without fear of busting out the cylinder wall.
It seems to me that the 400 CID small block Chevy's were Siamesed blocks that had steam holes and when guys would put 350 heads on for higher compression they would over heat when the steam holes were not add to the heads.
As to what this looks like in a Stage block, I'm sorry, I have no clue.
So are all the stage blocks this way? I'm looking at the blocks on gnttype and I can't figure it out. Some have two holes above and left and right of the center bore, and some have only one. Which, if any, is Siamese? And do the steam holes count for coolant passages? And if so does this make it not Siamese?
I'm having a mental block on all of this.
In production blocks the 3.8 isn’t Siamese but the 4.1 is. I’ve never had a stage block but since the outside dimensions are the same it would probably have the same Siamese bores. With the bigger bore there is no room for a water passage between the cylinders on the production block.
I was told my 0012 block is siamese. But I'm with you Joey, I see so many variations that i don't understand either.
This is pretty much what you need tp know. Typically you can see this through the open freeze plug hole.
On all production 3.8 liter blocks the cylinders have coolant circulation around the circumference. A production 4.1 liter block has a siamese casting like the example Allan attached above. All On center blocks no matter the bore size have a siamese casting. All Stage 1 3.8 blocks and most of the 3.8 Stage 2 blocks are not a siamese casting with the exception of a small handful that were cast for the Indy program. The siamese bore 3.8 blocks are much stronger and thicker cylinder walls and are the ones to buy. There were made at the point in the motorsports program where all 4 main caps were steel and they used a BBC rear seal rather than Buick. All 4.1 Off center blocks are a siamese casting also. The pic posted by Captrob is indeed a siamese bore 3.8 Stage 2 block.
You are the man! Clear as a bell now.
I hoped it made sense as I was writing it.
Perfect sense. Because I personally can't apply general engine knowledge to Buick blocks because I have no performance experience with anything other that a Buick.
I've seen 0012 blocks referred to as Stage 1 and Stage 2 blocks...I guess it depends on the oil pickup or drilled for the extra head bolts?
Also, the coolant holes are different on some other pictures of 0012 blocks than mine. Where the 2 square shaped holes are on my above pictured block are, this other picture I've seen doesn't have holes there. Different head cooling application? Same thing with the steam holes?
Stage 1 and Stage 2 3.8 blocks were machined from the same casting with the exception of the 3.8 siamese bore blocks. The major differences between the Stage I and Stage 2 3.8 blocks were the 4 bolt main caps, extra head bolts and oiling system. The 3.8 Stage 2 siamese bore block is essentially a small bore 4.1 block. The square coolant passage in the deck surface is the give away when looking at pics. I don't believe the difference in water passages serves any particular purpose the casting is just different.