Do small block 400's run hot??

[elimination]

I am thinking of building a chevy small block 400 and was told that they run hot due to the siamesed cylinder walls. This is a virgin block that was going to be bored .030 over and not raced, just used in a tow vehicle. If anyone had some tips or experience with these I would appreciate it. Thanks in advance. burningm

[beached 1]

Isn't the 502 bbc siamesed? Those are used all the time in marine apps. I wouldn't worry about it.

[wfodude]

In passenger car applications they have a habit of running hotter than a 350.You have the worlds largest radiator so it should not be a problem. Make sure you use long rods to get the full potential of the motor 5.7 at a minimum 6.0 would be better.

[mister460]

I know this sounds crazy but it works. Trust me! The 400 is a great SB motor. It ran hotter than the 350 because DUH!! it's bigger and makes more power! What may sound strange is this: Tap the steam holes and PLUG them then deck the block to make it all smooth. We always used to do this to the 400's and 377's that we built. NEVER had a problem with heat. It's a magic voodoo trick that I'm passing on to you all. Go for it, just use 350 rods in it. Yes, pistons are available.

[bakerman]

How you doing, the 400 sb is good for a small block. I run one 30 over does run hotter then then a 350.but nothing a good radiator and shroud won't fix. mine has 335 hp 410 torque not to start any problems but dont do the 350 heads i tried that and crack them the 400 heads are beter then the 350 heads and will produce more torque do to cc and the 400 was never put in to cars from factory!the best heads for the 400 are casting #3951598 or#3973493 there are more # of 400 heads if you need them but those are the two best # :cool: good luck

[fatalbert]

Early 400 SB had cooling problems; it was related to water circulation holes between the block and the heads. One of the prior posts identifed one way of curing the problem.
Later year 400s had a modified design, and eliminated the over-heating problem. I know, I screwed up my dads 1971 Chevrolet Caprice that had a factory 400 SB, rated at 255 HP. Good running sedan, but always had heating problems. Those were the days, 1971, and a brand new Chev Caprice with factory air for $5,000.00.
srs

[SShammy]

IF YOUR REALLY WORRIED ABOUT IT JUST PUT YORU 400 CRANK IN A 350 BLOCK.HAVE TO HAVE IT TURNED TO MAKE IT FIT BUT YOU GET MORE STROKE AND LOADS MORE TORQUE OUT OF THE STROKED 350 . HAVE IT BALANCED AND USE A GOOD FLEX PLATE AND FLUID DAMPNER(KEEP IN MIND THAT THE 400 AND THE 383 ARE EXTERNALLY BALANCED ENGINE THAT CAN BE QUITE CONTRARY IF YOU CHEAP OUT WITH CEDRTAIN PARTS. THERE IS A WAY TO MAKE ONE INTERNALLY BALANCED BUT IT COSTS MORE. ITS REAL EASY TO GET 400 HP AND 450 FT LBS OF TORQUE OUT OF THE 383. AS FOR THE 400 RUNNING HOT IN A BOAT. I REALLY WOULDNT SWEAT THAT AT ALL . JUST MAKE SURE YOU HAVE THE PROPER THERMOSTAT IN IT.

[HOSS]

The 400 small block was a piece of shit. That`s quite evident by the limited years(2) of production. Chevy quit using them in production because of overheating problems. The "steam holes" in the heads are the culprit.
As far as a 383, you need the crank, harmonic balancer, and flywheel from a 400. The block will have to be machined.
My advise, keep the 350 and invest in heads.

[Jungle Boy]

No problem with the 400ci block. Seen lots of them with no problems. If you are worried, drill & tap 3/8" holes in the water passages in the back of the intake manifold (one on each side). Exit the water through a couple of through-hull fittings. We do this on some of our small blocks and hav never had a problem with over heating.
Allso - My advice; 383 ci and other stroker combinations make the best torque and HP for small blocks. No disrespect Hoss, but in the "real" riverboating that we do, 90% of the guys are running some type of a stroked small block.
[ March 17, 2003, 11:35 AM: Message edited by: Jungle Boy ]

[HOSS]

None taken.

[wfodude]

you want some real fun....A 400 block with 6 inch rods and a 3.25 crank....Hold on to your pants cause it screams on top. With the right impeller....way cool. 383's work great if you use big heads and long rods otherwise they just make good truck motors. bore stroke ratio gets all jacked with the 3.75 X 4.0 combo.

[bakerman]

sorry hoss not to try to disrespect anyone but the 400 small block was built for 10 years from 1970 to 1980 with 3 differant blocks :cool:

[HOSS]

Cool, might want to inform data base for Oldsmobile and Chiltons. Or at least edition I have.

[malcolm]

400 1970-72 4.126 (2.65" main) 4 bolt
400 1973-80 4.126 (2.65" main) 2 bolt

[Jungle Boy]

Here's a photo of my boys. 383ci stroker and 434ci stroker. Never a lick of troubles with either.
http://www.***boat.com/image_center/data/521/259ENGINES-med.jpg

[bakerman]

Block # 3951509 400 S.B.C 70-71 4 bolt main
Block # 3951509 400 S.B.C 74-80 2 bolt main
Block # 3951511 400 S.B.C. 70-73 4 bolt main
Block # 330817 400 S.B.C. 72-80 2 bolt main
Thats what I have on S.B.C 400 blocks :cool: and sence I put the 400 heads back on no problems with it! mine is in my truck! :cool: