Discussion
I am told that the 383ci is the largest size for a small block (350ci) and a 396ci is a "big block". Is this true? Both engines have similar output (550/535 V's 550/550) but what is the difference? Is the block actually bigger??? Will it fit ok? What about performance characteristics?
Cheers for your help UltimaPaul - I am making good progress!!!
Cheers for your help UltimaPaul - I am making good progress!!!
Doz
l believe you can get a small block up to 427 and certianly 406. Look at the American Speed list of options as they are all small blocks for the Ultima.
www.amerspeed.com/
l believe you can get a small block up to 427 and certianly 406. Look at the American Speed list of options as they are all small blocks for the Ultima.
www.amerspeed.com/
I am told that the 383ci is the largest size for a small block (350ci) and a 396ci is a "big block". Is this true? Both engines have similar output (550/535 V's 550/550) but what is the difference? Is the block actually bigger??? Will it fit ok? What about performance characteristics?
Cheers for your help UltimaPaul - I am making good progress!!!
Good list of blocks is at this url. Blocks are different physical sizes. Some major overlap of capacity between SB and BB.
www.mortec.com/borstrok.htm
Also, a very confusing reply on Chevytalk
www.chevytalk.org/forums/Forum64/HTML/006446.html
396 is a small GM big block engine. However, theoretically you could build a GM small block with a 396 c.i. capacity with a custom stroke crank and custom bore size. The 383 is a GM small block with with a longer stroke crank. GM also made a 400 c.i. small block. The only thing that will work in an ultima is a GM small block. The big block engine won't fit without SERIOUS modifications. Not to mention its pretty heavy, and your limited by the transaxle (600-650ft. lbs of torque max). No sense in using a big block really. You can increase the bore and stroke of the factory GM smallblock to over 400 c.i., and GM, DART,BRODIX, and possibly World's sell a racing smallblock engine block with raised camshaft location that allows you to go up to 450 c.i. I believe. Pointless really for an Ultima with a Porsche or Getrag gearbox. A 350-383 c.i., naturally aspirated, smallblock chevy is capable of pumping out 600 ft.lbs of torque with the right set of heads.
Cheers!
-Mack
Cheers!
-Mack
world castings offers a crate engine small block chevrolet with 485hp out of the box
heres the .pdf link www.worldcastings.com/docs/catalog/pg32.pdf
and the engine is complete with everything including carb less externals sucha as water pump alternator etc
heres the main link to the site www.worldcastings.com/index.shtml
heres the .pdf link www.worldcastings.com/docs/catalog/pg32.pdf
and the engine is complete with everything including carb less externals sucha as water pump alternator etc
heres the main link to the site www.worldcastings.com/index.shtml
www.summitracing.com has these things for $7,500 - $8,650 U.S. for the cast iron and aluminum head versions. The motor also comes with a 2 year/24,000 mile warranty. Pretty good deal. You might ask the guys at Chevy Talk www.chevytalk.com how well they hold up.
Cheers!
-Mack
Cheers!
-Mack
This has been done for years in the States as a way to get a revvy SB Chevy with more displacement than 350 and enough room for really big valves. Keep in mind, however, that you have to use a siamesed block to build that engine--either a stock 400 block (stock bore 4.125") or a siamesed cylinder race block.
It's an "overbored 350" only dimensionally, since it has the stock 3.48" 350 stroke, but with a large 4.155" bore rather than the stock 350 4" bore. It's NOT an "overbored 350" in the literal sense, meaning you can't take a stock 350 block and overbore it to 4.155" without drastic, undesirable results.
In production cars, only the 400 block had siamesed cylinders. For racing, both Chevy and the aftermarket have sold siamesed cylinder small blocks, some even with the 350 bore of 4". These siamesed 350s are the only 350s that can be overbored to Chevy 400 dimensions.
It's an "overbored 350" only dimensionally, since it has the stock 3.48" 350 stroke, but with a large 4.155" bore rather than the stock 350 4" bore. It's NOT an "overbored 350" in the literal sense, meaning you can't take a stock 350 block and overbore it to 4.155" without drastic, undesirable results.
In production cars, only the 400 block had siamesed cylinders. For racing, both Chevy and the aftermarket have sold siamesed cylinder small blocks, some even with the 350 bore of 4". These siamesed 350s are the only 350s that can be overbored to Chevy 400 dimensions.
I'll tout the 377ci then which is a overbored 350ci
Amerspeed did this for me. 644 BHP at 7200 rpm
G MAN
Doz,
You came to the right conclusion. The AS 396 is a small block. Having grown up in the US and having read "Hot Rod" for years on and off, I'd heard of American Speed long before knowing about the Ultima, and IIRC AS only builds small block Chevy engines. In addition to that, not too many companies out there will build a 396 big block because it'd cost about the same as the larger bore 427 or 454, so there's no point. Very few people would want a 396 big block nowadays, and core 396 blocks to rebuild would probably be harder to find than the 427/454 block.
warning
The reason for the 383's popularity is that it can be built using no expensive components or hard to find parts. It can be built with any 350 block (4" bore) and a stock 400 (cast) crank (3.75" stroke), and these blocks are extremely easy to find--far more so than the siamesed block 400, though with about 60 million 1st gen small block Chevies built, these numbers are relative.
Furthermore, to build an engine with the siamesed block, the engine builder needs to know what he's doing. If it's not done right, it'll be prone to overheating, as there's no coolant in between the cylinders. This block has extra holes (steam holes) drilled into it, and they contribute to cooling. When you buy heads or head gaskets for SBC's, they usually don't have those holes. The engine builder or machinist must drill corresponding holes into the heads and gaskets, or it'll overheat. The 400 block got a reputation among the unknowing in the US for overheating simply because people didn't know how to set up these engines properly.
Thus, 383 and 406 (rebuilt 400 bored 0.030" over) engines can be built on a budget, however, if you want them to rev high and hold together, a forged crank might be a good idea. A forged aftermarket crank with the stock 400 stroke (3.75") was available from Summit Racing for about $600 a few years ago.
For larger engines, now you're getting into custom stroker cranks with 3.875, 4, or 4.125" strokes, and they cost big bucks. As bigmack said, there are aftermarket blocks with a raised camshaft as well as other mods so that they can clear a large stroke. Also, they even have such blocks with a taller deck for really large strokes, since a 4" stroke is pushing it with a stock block, and I'd guess that 4.125" stroke may need a tall block.
To confuse matters further, rounding off to the nearest cubic inch, 4.03" bore and 3.875" stroke = 395 ci. 4.125" bore and 4" stroke = 428 ci. But they call these engines 396 and 427 respectively for nostalgic reasons, since those numbers mean something to people who like the old musclecars with the old big block 396 and 427 engines.
You came to the right conclusion. The AS 396 is a small block. Having grown up in the US and having read "Hot Rod" for years on and off, I'd heard of American Speed long before knowing about the Ultima, and IIRC AS only builds small block Chevy engines. In addition to that, not too many companies out there will build a 396 big block because it'd cost about the same as the larger bore 427 or 454, so there's no point. Very few people would want a 396 big block nowadays, and core 396 blocks to rebuild would probably be harder to find than the 427/454 block.
warning The reason for the 383's popularity is that it can be built using no expensive components or hard to find parts. It can be built with any 350 block (4" bore) and a stock 400 (cast) crank (3.75" stroke), and these blocks are extremely easy to find--far more so than the siamesed block 400, though with about 60 million 1st gen small block Chevies built, these numbers are relative.
Furthermore, to build an engine with the siamesed block, the engine builder needs to know what he's doing. If it's not done right, it'll be prone to overheating, as there's no coolant in between the cylinders. This block has extra holes (steam holes) drilled into it, and they contribute to cooling. When you buy heads or head gaskets for SBC's, they usually don't have those holes. The engine builder or machinist must drill corresponding holes into the heads and gaskets, or it'll overheat. The 400 block got a reputation among the unknowing in the US for overheating simply because people didn't know how to set up these engines properly.
Thus, 383 and 406 (rebuilt 400 bored 0.030" over) engines can be built on a budget, however, if you want them to rev high and hold together, a forged crank might be a good idea. A forged aftermarket crank with the stock 400 stroke (3.75") was available from Summit Racing for about $600 a few years ago.
For larger engines, now you're getting into custom stroker cranks with 3.875, 4, or 4.125" strokes, and they cost big bucks. As bigmack said, there are aftermarket blocks with a raised camshaft as well as other mods so that they can clear a large stroke. Also, they even have such blocks with a taller deck for really large strokes, since a 4" stroke is pushing it with a stock block, and I'd guess that 4.125" stroke may need a tall block.
To confuse matters further, rounding off to the nearest cubic inch, 4.03" bore and 3.875" stroke = 395 ci. 4.125" bore and 4" stroke = 428 ci. But they call these engines 396 and 427 respectively for nostalgic reasons, since those numbers mean something to people who like the old musclecars with the old big block 396 and 427 engines.
Steve_D said: G Man
I have heard of 23 degree heads and now you speak of 18 degree.
What does this mean?
Steve
Ok A Chevy SB has a 23 degree value angle in the head which even after porting won't give great flow figures so the NASCAR boys and the DIRT late model racer starting using 18 degree heads, it basically allows better flow, but things move on and we talk about 14 dgree heads and less.
The compression is not a worry on an 18 degree head
www.chapmanracingheads.com/p_cylinder.asp?ID=30
>> Edited by G Man on Monday 23 December 14:17
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