View Full Version : so sad
04-09-2001, 09:49 PM
well its a sad day in 350 land as mine has died once again. i am finally putting it to sleep. can anyone give me some perks and or problems with a 400 small block?
what kinda carb should i run? will it give me trouble with a 350 turbo tranny behind it? or will it give me trouble period??? thanks in advance for your input
04-09-2001, 11:49 PM
I havent heard anythign bad to be bashing a 400 but the way I look at it:
So many parts.....
So many still avalible.....
So many still out there running well.... :)
04-10-2001, 01:50 PM
400sb is a great motor. if you have one already available, then I say go with it. it will bolt up to just about anything that any other small block will, and take all the same bolt on parts. carb? i would recommend a q-jet but if youre into the square bore carbs, any will do.. id probably run a 650 or 700cfm max especially on a mild motor.
you wanna make sure your cooling system is in excellent shape.. some say the 400 creates a lot of heat.. one thing i know is that they are a little more susceptible to heat damage so you dont want em getting hot in the first place..
i run a sb400 and probably will always, ive had real good luck with mine..
thats my opinion
OK, here's my opinion(s):
To get the 400 cid into a small-block package, the cylinder bore had to be increased. This means there is no water jacket between adjacent cylinders ("siamesed" bores) which is why the 400 is more susceptible to damage from overheating. As long as your cooling system is in good shape & you pay attention to the temperature gauge, there should be no problem.
400 is the same (externally) as a 350, so bolting up to the T350 trans will be no problem, and the transmission should handle the 400 engine OK.
Just remember that the 400 is balanced externally - they use a special flywheel/flex plate and harmonic balancer because with the extra bore & stroke stuffed into a small-black package, there isn't much room for counterweights on the crank. The 350 flywheel/flex plate & balancer will NOT interchange.
As for carb, I like the Q-jet, especially for everyday driving.
The 400 is more of a "torque" engine, not as much top end/RPM as some of the other members of the small-block family. In my opinion, torque & low/mid range power is what you want in a truck - at least one that's used as a truck!
If you have or can get a 400, by all means use it! Since it'll bolt right in where your 350 was, it should be a simple swap and if for any reason it doesn't work out (always check out a used engine thoroughly if you go that route!) a 350 can go right back in.
04-10-2001, 06:04 PM
For a truck the 400 is the way to go,torque,torque and more torque.I replaced 350's with 400's twice-both times the truck went from barley adequete to super truck-capable of topping big hills with no problems at all.
Just wondering John - I know this is going to vary a lot from one area to the next, but how readily available are 400's? I don't see them too much around here in the used marketplace - maybe those that got 'em, hoard 'em! :D
My 350 does fine (4:10 gears help for pulling power, but are lousy for mileage!) but the extra 50 cubes & more torque are always good. Changing an engine in an old truck like mine is real easy, so I'd gladly drop a 400 in some day.
If my memory is right, I think the 400 made more torque than the old 396/325 hp did. And made it at lower RPM as well. If I can ever find a decent late 70s chassis to build the way I want it WILL have a 400 in it.
04-12-2001, 05:58 PM
thanks for all your input guys. im leaning more and more toward putting a 400 in my truck. just a few more ?'s can anyone recomend a tranny to back it upand possibly a transfer behind that? thanks again
Here's my 2 choices for trans/T-case:
Manual: 4 speed/205
I realize these may not be the best combos from a gas mileage standpoint, but I like to build strong!
04-12-2001, 08:36 PM
for tranny + transfer case its personal preference.. 205 is a strong beast, 203 is a good case too and you can get a 2 wheel lo-range with the part time kit, which I really like, plus they're cheap.. turbo400 automatic is a beast but it takes more power to turn and is more expensive than a turbo350.. turbo350s can be built extremely strong, too. 700-r4 is an excellent choice also, with its overdrive.
let us know what you choose
You bring up good points Mike: my 2wd dually has a 350/T400 and it's strong but likes it's fuel! I am building a 4x4 now, it will have a 350 (or maybe a 400!) with the 4 speed/205 combination and it too will be very "friendly" with OPEC. I like 'em strong so I can plow/tow/winch but I don't do a lot of long distance driving and I pretty much have the truck parked in the summer months so the (lousy) fuel mileage isn't a big problem.
The 700r4 with that extra gear is a good choice to help bump fuel mileage up, and the 203 T-case is a decent unit too.
So if I may add to your post: "For tranny + transfer case it's personal preference AND what you plan on doing with your truck".
04-13-2001, 02:37 AM
I have never had a 400 SB, 350's and Big Blocks are all I have had.
My K5 came with a 400 th350 and np-203 t-case.
The guy I bought it from said that plant was strong as hell.
Now it has a 355 plant,sm465 gearbox and np205 t-case.
After the addition of the 33's I have lost alot of power.
Not to worry, I have a .040 over 454 waiting to drop in her.
04-18-2001, 12:35 PM
The comments on the SB 400 are right on, siamesed cylinders, etc. Another thing is that they were all 2-bolt mains, but that shouldn't matter for your application.
The TH400 is definitely stronger than the TH350 and 700R4, but is more expensive and has more frictional losses. You should determine what you will be using the truck for and go from there.
Personally, I am running the factory 454 and TH400 in my '76 Suburban, with some bolt on goodies to help it breathe a little better.
04-18-2001, 07:49 PM
Jeffs Classics: surely you dont mean ALLLLLLLLLL sb400's were 2 bolt mains, right? possibly all of them in our trucks, but definately not every single one :) just wanted to clear that up.. i say possibly because im not really sure which block they used, when.. I tend to think that for a street/daily driver, that a 2 bolt will never let you down. and they say that the factory 4 bolt main 400's are not good for extremely high output motors, because of where the holes are drilled for the extra main bolts, supposedly it weakens the block, and the way to go is to buy aftermarket splayed caps.. at any rate, judging from all ive seen and heard, the 2bolt vs 4bolt main thing is way over-rated and i would not hesitate to build a 2 bolt.. thats just my opinion
Mike - I did some searching on my bookshelf, and what I was able to find out was the 400 had 4 bolt main caps in the years 1970 - 1972, from '73 on it had 2 bolt mains.
And, I'm inclined to agree with you on the 4 bolt vs 2 bolt question - for street use I don't see anything wrong with a 2 bolt main engine either.
04-26-2001, 09:07 PM
400sb rules!! I run a 400/TH350 combo with a 203 t-case with no problems at all(mind you my tranny is built to the nuts). I run 35-inch tires and use the truck HARD(from towing to hauling to playing). I say go for it!!
04-26-2001, 09:17 PM
400's are getting tougher to find now-but so are driver side dipstick 350's.Unless you use a GM service replacemnet block with dipstick holes on both sides,most now are pass side dipstick.
04-28-2001, 09:00 PM
well all i have found a very solid 350 form a friend of mines brother. its been bored 30 aver and has keith black dome pistons, roller cam, roller rockers, holly high rise intake, and a very healthy holly 750cfm double pumper. it has a turbo 400 hydrostatic tranny that needs rebuilt but i figgered that for 500 bucks i cant pass it up. i have yet to figger out what kinda transfer im gonna put on it but when i find one ill let you guys know
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