Small Block 350 vs 400

[78 Chevyrado]

Nice looking engines^^^

Here's some info on the steam holes, where they are located, how to drill them.  this guys putting 350 heads on a 400, but it applies to any head on a 400.  The cylinder bores in a 400 are siamesed, or have no space between them like all other small blocks for coolant to flow between them.  the steam holes let out air that can get trapped because of the siamesed bores.  thats all it's for, they don't vent steam or anything like that.
http://www.gregsengine.com/350to400.htm   

i think 400's got a bad rep from the start because all (or some) of the 400s from 1970 (first year) came with no steam holes in head or block, which made them overheat.

Main thing to watch for being externally balanced is that you must have a 400 specific flexplate/flywheel and harmonic balancer.  Sometimes the outer shell of the balancer can slip and get out of phase with the inner hub, making the balancing be off. 

as far as fans, you can't have too many, especially flogging on it in a mud bog or trail at slower speeds.

reason I'd recommend a forged crank at least is, while a cast crank (iron or steel) is plenty strong, when mudding, you may come up on more shearing-type (I hope that's the right word) forces.  meaning if you are going all out and something all of a sudden puts a sharp strain on the engine, like if you full throttle went from gravel to asphalt it can put a hella lot of force on everything.  since you broke a crank before, it may be a worthwhile upgrade so another block doesn't get destroyed.

[BlueCollarRon]

Thanks great advice.  I definitely want a stronger crank, it still bugs me why it happened.

Just to clarify, those aren't my motors. Just nice eye candy

[VileZambonie]

Rev's mean diddly when it comes to power and torque when you are comparing powerplants. Useful torque and horsepower is what's important. If you want different operating driveline RPMS change your ratios. For a heavy truck with large tires larger displacement and a longer stroke will be better.

[werewolfx13]

..That 350 blinded me with its bling 

[Captkaos]

My buddies 400 was built for less than $2000 and it was balanced to spin to 8500, it saw it on several occasions, we street raced it during the winter.
Fact#1 = that was the official documented power of the motor.  The 302 which was smaller in size made was documented at 290 at 4400rpms.  It would spin to 8500...  There was alot of discussion on this.  NRE built one a few year back and it made 500hp@8500...  BTW, all of GM's top motors were under rated.  If you notice none of them were ever rated over 375 (this was for insurance reasons)  BBCs were never over 435hp.  BTW the L89 was rate 5 more HP than the Aluminum ZL1 which made realistic 500+hp also, same goes the L88 "race" motor, rated 430 hp @ 5200 rpm, it was good for 500+ at 6800

Fact #2 and 3 Not sure of the relativity... unless you saying GM also agrees bigger is better by going up in size, they did testing and speced the motor for durabiltity and performance when designing it...  Same thing with the LS9 which is 378ci.  Redline BTW is 6600...

Fact #4 10 years for the 400 is 3 more than the 327..  If you notice the trend, engines have gotten larger not smaller for performace reasons.  

Fact #5 By the time the 400 came on the scene the Gas Crunch had begun and performance was thrown in the trash.  No real development was done on anything up until about 1985 when the TPI came out..  BTW as far as numbers of engine with X motors the 350 buy FAR and the 283 were the more popular engines..

I think I have a pretty good understanding on bore vs stroke, the problem is The motor could max at 5000 rpms.  It is the Diff gears that make the rpms at the tires....

[BlueCollarRon]

Vile-

I plan on running 36' super swampers, at that size I should be able to spin them like a raped ape!  Some guys go too big on the tires and they get screwed.  So what would be my ideal gear ratio, I still don't have all that learned yet?  I of course will upgrade 3/4 or 1ton runnin gear when I get the new tires.

[VileZambonie]

I would run 4.10 if you are going with the 700R4

[BlueCollarRon]

700 is too weak, im going th350, and i already have a th400 to take its place.

[406 Q-ship]

Look guys, stating your opinion as fact is just plain, well uneducated.
Fact #1 the 327 had the highest hp output of any naturally aspirated production gm sb engine until the 2002 Corvette z06
Fact #2 the 2002 z06 engine was a 350
Fact #3 the 08  Vette engine is 366ci
Fact #4 the 400 was only manufactured for 10 years, if it was so good why only make it for 10 years? They still made big blocks so the mpg thing is out the window.
Fact #5 the 400 was never used in the Corvette by gm which being the flagship Chevy car always got the best motors, yet the 327 was and so was the 350 as well as big blocks odd isn't it how the 350 and 327 are the 2 most popular corvette engines. I find it also interesting how during the 70's while the 400 was being produced the 350 was the base corvette motor.
Anyone ever wonder why most 400's output was around 250 hp which is around 100 hp less than the 327's? Ever wonder why gm did away with the 400?
A 400 turning 8000 rpms? On a daily driver? On a budget the OP could afford? That's a pretty big claim.
Why didn't GM bring back the 400 in the second generation small block? There has to be a reason especially with the Mustang walking all over everything Chevy made in those years.
Capt - I beg to differ with you. Getting a 327 to turn 8000 reliably is going to cost a lot less than a 400. A 327 makes 350 hp with a hyd cam, they actually call it the 350 horse 327 cam. You could drop a hyd roller cam in and get 400 hp. I think that should be all the power it would need and it can live in the 6000 rpm range all day long and be perfectly streetable, actually tame. Simple physics proves the shorter stroke of the 327 will spin faster than the longer stroke of the 400 or even the 350. The crankshaft even with no pistons attached will be capable of spinning faster. Have you ever watched a figure skater do there spin move? Did you happen to notice as they brought their arms and knees in towards the center they speed up? When their arms are out can be thought of as the longer stroke than when everything is close to the center line.
I agree that a big block is a better choice if it can be afforded because then the jump in horsepower allows you to use gearing to get those tires spinning at the right rpms. As an added benefit the bbc would still be very streetable.

1st off Chevy never did a HiPerf version of the 400 because at the time they did not know how to make it reliable in a regular driver with a warrenty, remember the 400 is a short rod engine which causes higher friction.  The 400 was made for smaller lighter engine in trucks and big cars where it did its job without protest.  Ask yourself this question why did Chevy make a SBC 400 when they already had the 402 BB.  With today parts a 500 ft/lbs 400 with long rods is easy as falling off a log, and no 327 will ever make 500 ft/lbs at a streetable RPM and that is a fact.  Torque is what moves our heavy trucks and horsepower is just a math formula.  I will agree that the 327 has the greatest HP to cubic inch ratio of anything except the LS series, but torque makes a much better street driver, another fact.

Why would he build a stroked 350 when he already has a 400?

I'm gonna steal a line from my 4-yr old boy....."Because!".

I dunno, never had a 400, but, I have a 383 and that puppy has loads of torque.  Torque is what makes an  engine go.  'tis why they are called stump pullers.  Love mine.  Anyone else would love there's.

But, as mentioned, c.i.d. is  boss.  Go with displacement--i'm outvoted www.delbridge.net/install

383 is just a 400 crank in a .030 over 350 block, if you put that 3.75 stroke back in the 4.125 bore block where it belongs it tears up the 383.  The larger bore unshrouds the valve allowing the heads to work to their full abilities. 

[fitz]

   There has been lots of debate about the 350/400 and which can be built into a better motor. I've owned both(still do) and don't think you can go wrong with either. It sounds like your just looking to get your truck back on the road as quickly as possible. From your post in the Projects Section it sounds like you own the 400 already as opposed to the $200 350 that is shown covered in snow.
  If you know that the 400 is a good motor I say bolt it in and get the truck driving again. The 350 appears to be a Goodwrench replacement motor by looking at the valve covers. Captkaos has a Link to the Car Craft buildup of this motor the Tech. Section. That could be a good project when time/money permits.
 As far as the trans, your keeping the 350 but mentioned you had a 400 for it. Just keep in mind the 400 uses a different transfer case.
  Like Vile said cooling can be an issue with the 400. You may want to go with an electric fan. He has a few good post about wiring them and the aluminum shroud he made for his. I mounted mine under the stock plastic fan shroud. Let me know if you need pics.

[VileZambonie]

700 is too weak, im going th350, and i already have a th400 to take its place.

Tell that to the Big Block Blazer I built 8 years ago that still has the same 700R4 behind it burning rubber all over the place. I'd build a 700R4 over a th350 any day. Having overdrive allows you to run steeper gears and get better fuel economy. Upgrading the weak links in a 700R4 is inexpensive and easy.

[Captkaos]

I agree with you Vile, I would much rather have a 700 with OD than a 350..  Of course I prefer EFI over carbs too...

[fitz]

700 is too weak, im going th350, and i already have a th400 to take its place.

. Upgrading the weak links in a 700R4 is inexpensive and easy.

What is the weak link and how much $$ is it to fix?. I swore off the 700R4 because back in the early 90's most tranny shops couldn't fix them right. Probably lots of updates for them now, and like you said before, some people just need new mechanics. How about the 4L60/241 set up from the 89-91 Blazers/Suburbans. Are they an improvement for our trucks over the 700R4/208. 

[BlueCollarRon]

Vile- are you turning 36' or greater tires with that big block?  From my understanding the 700 doesnt like it when you have to rock yourself out of a mud hole ( reverse, drive, reverse, drive) and on top of that the 700r is the most expensive tranny o rebuild, at least around here. 350's and 400 and much cheaper, easier to rebuild, and easier to find.

What do you think about my gear ratios since I am running a 350 now and will be a 400 in the future (trannys)

BTW I bought that motor last night and dropped it off at the shop.  Hopefully I can pull it into the shop tonight to thaw it out, then I can do something about my truck.  I might just run the 350 since it is ready to drop in, then that will let me get some cash to build the 400 up for a real mud truck.

and I prefer carburetor over efi

[Captkaos]

How about the 4L60/241 set up from the 89-91 Blazers/Suburbans. Are they an improvement for our trucks over the 700R4/208. 

A 4L60 IS a 700R4, same trans.  In fact a 4L60E in the newer trucks is the same as a 700R4.  May parts will retro back on them to the 700R4s. 
Many 82-86 700R4s were junk and had alot of issues that were fixed over time.  By the time you hit 88 all of them were getting the new upgrades, but earlier ones couldn't take all of them...
They gain an unfavorable rep because of the earlier models, but they are just as strong as a TH350 if not stronger.

You can build one handle 600ft/lbs before breaking under repetitive abuse.