RE: 400 sbc
 

The 400 chevy does have a tendancy to get hot and yes if you are going to build it it should be sonic checked for thickness. They have simeased (sp) cylinders and require steam holes in the heads. Certion ones of these are more desirable (the 4 bolts are less desirable) and are worth more than a 350. The 509 casting is a desirable one. Apples to apples the 400 will have more performance advatageover a 350.If you are looking to build a 383 the 400 crank is the only thing you would use from the 400. Pistons from a 400 will not fit in a 350. The mains in a 400 crank are bigger so you would need to getthe crankturned down to the 350 size. Scat makes a resonably priced 383 crank it mignt be a wash having the 400 crank magnefluxed and turned verses just buying a Scat 383 crank.

RE: 400 sbc
 

The biggest problem with the SB 400 is that there is not enough room between the center cylinders to put a normal size coolant passage. They have small passageways I think GM called it the Steam holes. At factory HP this is not much of a problem although blown head gaskets at higher miles are common.

If you increase the HP you increase the amount of heat that needs removed. This is where the steam hole begins to fail. The 383 is much better setup for dependability. I knew there where some circle track teams that ran the SB400. The one team I knew used to pull the heads and replace the head gaskets every other race. We could go half the season without a tear down with out 383.

If you are going to be under 350 HP and drive it hard once in a while the 400 will be fine. If you are going to drive like you stole it or you shooting for over 350 HP go with the 350/383.

Edit, Dang I didn't see the second pageGRIFFgot it right, oh well

RE: 400 sbc
 

I've heard that before but never actually seen it,I had two of those 400 motors and both were great runners with no troubles.
One was in a 1978 GMC full size Jimmy (think K5 Blazer) and the other in a big black 1972 Impala two door,both heavy rigs with automatic trannys and neither ever overheated.

http://www.chooseyouritem.com/classi...onvertible.jpg

RE: 400 sbc
 

some times you might have good luck with these engines, but if your running high hp numbers, you need to keep them cool. my friend has a 400 sbc and never had a problem, but its a marine motor and its only got like 275 crank horse or something. like gorn said, much over 350 hp, is pushing it for those motors. i say just put the 400 in there, and drive it nice and calm. when someone thinks your cars got no nut, then show him up. but dont do much more to the engine so you dont push it for cracking the cylinder walls. if you do run 350 or more, put a really good high flow water pump and a big electric fan thats constantly running.

RE: 400 sbc
 

The design is good for stock HP even a little past that. Once you push the motor hard (IMO over 350 hp) the small steam holes can not keep up and creates a hot spot between the cylinder. Thatleads toa head gasketfailure. You will not see the over heating on the gage causeyou can not get enough coolantto the hot spot so the coolant temp does not rise. If it was a matter of just getting to hot you could put a bigger rad in it.

RE: 400 sbc
 

Can i put a TBI manifold on the 400 or should i take the entire fuel lines, carb and intake from the other Camaroand use that instead?

RE: 400 sbc
 

I believe the manifold changed in 87. The boltangles are different. You may be able to mod it if you willing to tackel all the other issues you will have with the fuel injection. You will have issue to how the computer is programmed. Example the 400 needs a lot more air and fuel to idle then a 305.

Have the steam holes drilled in your heads, the straight bottom drilled holes will do, and get a high performance, high flowing water pump along with an aluminum radiator and you will be good to go. I run a built 400 in my 82 Z-28 with a set of dual electric fans from a 4th gen camaro Z-28, things stay cool. When you drive a nicely built 400, you will not want to go back to the 350, as they say, there is no replacement for displacement. I had a built 355 in my Z-28 and it was quick without a doubt, but then I built the 400 last summer, and well to say it is better, is an understatement. Just make sure your cooling system is in good working order, afterall, GM put these motors in cars and trucks for about 10 years or more, and didn't have the high performance cooling system parts back then that we have today.

i did a a swap like that from a 305 to a 400 sbc with a bw t-5 tranny. i swaped the tbi intake over to the 400, all you have to do is drill out the 2 inside holes on each side of the intake to match to 45 degree angle on the 86 an earlier heads. 87-85 the int inside intake bolts are angled 12 degrees. and with the cooling system, i run 475hp an 501ftlbs, you jus gota have a good cooling system like what cc82z28 said.

hi i got a question, im doing a 305 tbi to 307 carb swap with a t-5 trans.... what can i do about the flywheel issue? i have pretty much NO MONEY....