Small Block 350 vs 400

[choptop]

Somebody explain something to me. If the main idea is to get maximum wheel speed, why not got with a torque monster bigblock, and gear the truck higher for the wheel speed. It takes the torque to get to the wheel speed, and horsepower to maintain right? Seems a bigblock could easily spinup some 38's and have enough horsepower at 5500 rpm to maintain it. Is this thinking correct???

Yep, that is correct.  I said that earlier:

the problem is The motor could max at 5000 rpms.  It is the Diff gears that make the rpms at the tires....

Ok, I did see that earlier, but had a brain fart.

[eventhorizon66]

Just so you know, in the 2002 Car Craft Real Street Eliminator contest, a huge boat of a 1982 Cadillac Fleetwood, owned by Jeff Schwartz, won overall with a hot caddy 500, a TH400, 2800 stall, 2.73's in the rear, and 26" tires.  His 1/4 was an 11.80 @ 116.05.

[Fishtail8]

In my old 4x4, I ran a 406,4L80E/205, 4:10's with 36's.  Here's the simple build we did for the 406.

Stock block, stock crank, main studs, 5.7 inch rod, custom forged piston, balanced, 10:1, Comp XE268H, steel Pro-Action 180cc heads with 1.6 roller rockers, Performer RPM intake, 750 vac sec Holley.  Dyno'd at 392hp & 444 ft-lbs.  400+ft-lbs from 2500 up. I wheeled the shoot outta that engine, kept the rpm's under 5000, and never have had a problem.  In low range it was more than enough to get the job done. I can scan the dyno sheet if you want. 

Build for torque, screw the horsepower. 

Off topic a bit, when I parted the truck out, I threw the engine in an ole Pontiac I was building, and being 5yrs old and abused, it still runs 12.80's @105.  Done... Build away... 

[cracker0169]

I vote 377 and 5.13s 

Throw some big Dart heads on there and a big roller and let her eat!

[Layne]

I was once told you can put a 350 crank in a 400 and make a 377 that would "run 9 grand all day"

[eventhorizon66]

You were told wrong.  Any SBC has to be purpose built to "run 9 grand all day".

[bigkountry]

377 is a high revving engine, but as pointed out above it has to be purpose built. You are talking big bucks right there.

[Stewart G Griffin]

Shame on you for crushing that malibu;  It looked like it had many more miles in it.

i mean seriously.

[Layne]

That's what I thought. lol. So a .30 over 350 is a 355, then with a 400 crank it's a 383 right? Then a 400 .30 over is a 406, but if you use a 350 crank it's a 377? Can you make a reverse 383?

[eventhorizon66]

That's what I thought. lol. So a .30 over 350 is a 355, then with a 400 crank it's a 383 right? Then a 400 .30 over is a 406, but if you use a 350 crank it's a 377? Can you make a reverse 383?

That's all correct.  But what do you mean by a reverse 383?

[Layne]

400 block, 350 crank? that's a 377? so do you bore it out? I confused myself, but there's so many variables, I just wanted to clarify for myself lol!

[eventhorizon66]

A 377 is technically a 400 block bored 0.030" over with a 350 crank (3.48").  IMO, for any street engine, go for cubes first.  If I had a good 400 block, I would never use less than a 3.75" crank in it.  Revving high is not of any importance in a street engine.  Power and durability are.  So 406 cubes are better than 377 cubes, period.

[Layne]

Cool! Thanks for the clarification. Now I can act like I know it all in front of my friends!! lol! They're all about the b16 hondas or whatever they are. Gotta stick to my V-8s

[Gusgusa1]

I love all the info but with out purpose building which would be better at stock 350 tbi or a stock 400? Used for a daily driver and some weekend mud/ bush trails.

[rich weyand]

Depends.  350s are everywhere, the parts are available and cheap, and you can usually find stock parts salvage.  It's pretty easy to get in the neighborhood of 400 ft.lbs. out of a 350, even with stock heads, if you cam it right.

That having been said, the old posts above are right: torque is what matters, and there's no replacement for displacement.  The 400 can be set up for more torque than the 350 with the same amount of work.

Gas mileage in a 350 TBI will be much better than from a carbed anything, and more cubes generally speaking means more gas.