Siamese vs Non-Siamese cylinder bores

[GT63]

I've been looking at some of the aftermarket small blocks and noticed that some have Siamesed Cylinder bores and some do not. Is there any benefit to either configuration? Even the new GMPP blocks are coming out with Siamesed cylinder bores. Just curious what others have experienced.

 

[putz]

I've been looking at some of the aftermarket small blocks and noticed that some have Siamesed Cylinder bores and some do not. Is there any benefit to either configuration? Even the new GMPP blocks are coming out with Siamesed cylinder bores. Just curious what others have experienced.

Never heard this term before here is the explanation for others.Siamese blocks are solid casting between the cylinder bores. There are no water passages between them.This is done to increase the strength of the block." That's what ford says

 

[Photoman]

It just means there are no water passages between the cylinders. The 400 SBC block is siamese. Not the best design but required with big bores in cylinder blocks that are smaller.

 

[Mike]

It just means there are no water passages between the cylinders. The 400 SBC block is siamese. Not the best design but required with big bores in cylinder blocks that are smaller.

Perzactly!

Siamese cylinders will generally be more stable, because of the additional metal at the bottom of each cylinder. In some cases, siamese cylinders can have different cooling requirements, but that's certainly not a deal-breaker.

There are different methods of filling water jackets in a block, to provide more stability. Anyone remember using cement and rattling the outside of the block with a muffler gun to help the stuff settle? A few years back, we even had an epoxy-based resin filler we used. It was nice, because it had the consistency of room temperature pancake syrup, so it would pour easily and settle uniformly.

 

[Gerry]

Perzactly!

Siamese cylinders will generally be more stable, because of the additional metal at the bottom of each cylinder. In some cases, siamese cylinders can have different cooling requirements, but that's certainly not a deal-breaker.

There are different methods of filling water jackets in a block, to provide more stability. Anyone remember using cement and rattling the outside of the block with a muffler gun to help the stuff settle? A few years back, we even had an epoxy-based resin filler we used. It was nice, because it had the consistency of room temperature pancake syrup, so it would pour easily and settle uniformly.

Now we are talking 1/4 mile stuff, aren't we. I even heard of a guy who filled his block with sand to stop his problem with overheating. Liquid silicon was another one.
The old Topo has thrown water a couple of times. Race officials dont like that, they tell me off and make make cry. Luckily I dont run with antifreeze, which has now been banned on the strip as its harder to get cleaned up than regular oil.

 

[Mike]

Now we are talking 1/4 mile stuff, aren't we. I even heard of a guy who filled his block with sand to stop his problem with overheating. Liquid silicon was another one.
The old Topo has thrown water a couple of times. Race officials dont like that, they tell me off and make make cry. Luckily I dont run with antifreeze, which has now been banned on the strip as its harder to get cleaned up than regular oil.

We would use two quarts of filler per side of a standard SBC block and end up with a couple inches between the filler and the deck. It let us circulate water at the top of the block only and it really never caused any over-heating issues.

We even would do single quart fills on some stout street motors. Just enough to give the bottom of the cylinders a place to anchor their feet.

 

[Gerry]

We would use two quarts of filler per side of a standard SBC block and end up with a couple inches between the filler and the deck. It let us circulate water at the top of the block only and it really never caused any over-heating issues.

We even would do single quart fills on some stout street motors. Just enough to give the bottom of the cylinders a place to anchor their feet.

Now thats what I would call Brave
G

 

[Old Rotor Flap]

We used to use a block filler that I think was called TuffBlock or ?? It was a white powder much like Plaster of Paris and I think Mickey Thonpson or Donovan sold it.

 

[jonny440]

Not to hijack but can a Siamese-Bore block be run on the street or will you have bad over heating problems?

 

[Mike]

Not to hijack but can a Siamese-Bore block be run on the street or will you have bad over heating problems?

Pretty hard to hijack a thread that is over 3 years old.

As was pointed out, earlier in the thread, the 400 Chevy block uses a siamese bore configuration. Yes, a 400 can run hotter in some conditions, but if the cooling system is designed correctly, it becomes a non-issue. With high compression ratios (I'm talking about 12.5:1+), or with something running a ton of boost, the siamese bore configuration can provide some stability. For the majority of engines being built for street T-Buckets, it's nothing to be concerned about.

 

[jonny440]

Hi Mike true about a three year old thread I was just trying to be polite. Thank you for the answer just wanted to know if I buy a after market block to build and engine and can only get a Siamese block I can use it.