For all the Small Block 400 Guys!!!

[Hazieview]

Hey guys I have recently stripped my sb400 down to the block. This is the rebuild I am considering with the AFR Aluminum heads.

http://www.popularhotrodding.com/eng...ine/index.html

The reason I like these heads so much is that you can run on low octane fuel and still have big gaines. My question is this.....

How effiecient is my engine going to be?

I know horse power and fuel mileage dont mix but I dont want to be getting 5 miles to the gallon. If that was the case I'd be getting a big block.

Also is it even worth building or should I invest in something else for the money to power ratio?

Waht do you think?

[pokethesmot]

i love the 400 sbc but i have no clue about ur question

[78BO]

I'm looking at these heads for when my warranty is up. Right now I have a 383 with vortec cast heads. It dynoed 405 hp at the crank. But I've seen a few sets of topend kits that put out 460hp with just a basic 350 block and 8.5/1. I would be willing to bet with my built bottom and these heads and cam I could be close if not over the 500hp range. But that's got to wait lol, too many pies in the oven right now.

[crossy]

fuel mileage depends a LOT on where your sweet spot is on the curve and getting that particular RPM through gear ratios. Spread bore carbs are a big benifit too. 400's are not known to get good fuel mileage. remember big blocks started at 396 CID.

[pokethesmot]

so is a 400 a sbc or a bbc

[3r!c84]

SB! lol its a big small block.
the easiest way to tell is look at the header or manifold
BB all 4 are sped out . SB the middle 2 are close

[tvblazer78]

Originally Posted by 3r!c84

SB! lol its a big small block.
the easiest way to tell is look at the header or manifold
BB all 4 are sped out . SB the middle 2 are close

Small Block..

[dammitmitchell]

that's why it's called a SBC 400 pokes...
goober..

[3r!c84]

lol this is what confused him :remember big blocks started at 396 CID.

[manimal]

400's a great engines,EXCEPT for the 4 bolt mains. They are known to crack in the main webs.

[LONGHAIR]

Originally Posted by 3r!c84

lol this is what confused him :remember big blocks started at 396 CID.

I think that the real confusion came from Chevrolet.....They call the Big Block engines that they put into the 67-72 generation of trucks 400...even though they were actually 402.
IIRC they did the same thing in "low performance" big body boats (Impala, station wagons, etc)

396s and 402s were only used in preformance oriented cars....Camaros, Chevelles, Corvettes, Novas, etc....

The small block version of the 400 was used mostly the same way, big tanks that needed the torque to get them moving, not really in Hi performance cars.

[Manbearpig]

Originally Posted by 3r!c84

lol this is what confused him :remember big blocks started at 396 CID.

Nope 366!

[pokethesmot]

Originally Posted by 3r!c84

lol this is what confused him :remember big blocks started at 396 CID.

yeah lol

[pokethesmot]

Originally Posted by LONGHAIR

I think that the real confusion came from Chevrolet.....They call the Big Block engines that they put into the 67-72 generation of trucks 400...even though they were actually 402.
IIRC they did the same thing in "low performance" big body boats (Impala, station wagons, etc)

396s and 402s were only used in preformance oriented cars....Camaros, Chevelles, Corvettes, Novas, etc....

The small block version of the 400 was used mostly the same way, big tanks that needed the torque to get them moving, not really in Hi performance cars.

man thats good cuz my truck is a tank lol

[Albatrossian]

Getting good mileage doesn't consist of just the engine. It also depends on transmission, rear gear ratio and vehicle weight. Also remember that 405hp at the crank is NOT the same as 405 at the wheels. You can lose as much as 100hp just from parasitic loss through the driveline. Also remember that 400s, while they are good engines, are prone to cooling issues because of the lack of steam passages. If you're going to use the 400, make sure your cooling system is up to par or you will have problems.

[Chlsnk]

Actually didnt the BBC start at 348cid?

[crossy]

Originally Posted by Chlsnk

Actually didnt the BBC start at 348cid?

the 348 and 409 are usually referred to as 'W' motors due to valve cover design.

big trucks had big blocks as small as 366 CID
passenger car big blocks started at 396, 402,427 & 454 and in 69-72 trucks and 70-72 big cars ,for some unknown by me marketing reason, they called the 402 big block a 400 big block in everything BUT the Chevelle, Nova & and Camaro where it was still called a 396 instead of a 402. SS396 just hada good 'ring' to it.

[RPOZ11]

Originally Posted by manimal

400's a great engines,EXCEPT for the 4 bolt mains. They are known to crack in the main webs.

I am in COMPLETE agreement with this statement!!!

[clinebarger]

ive had 2 400 sbc both cracked the lower row of head bolts but the nitrous might have had somthing to do with it. and the short rods dont help either. if your really serious about having a 400+ ci small block invest in a bowtie block.

[RPOZ11]

Originally Posted by clinebarger

if your really serious about having a 400+ ci small block invest in a bowtie block.

MoTown & DART would be suitable cadidates as well

[clinebarger]

Yes sir they whould.

[aaronschendel]

I build a 406 in my garage two years ago. I am using World Sportsman II heads and I used a longer rod. It's a major torque monster. I had the block drilled for steam holes when I had the machining done. I ran it for two years with the stock cooling system with never an overheating issue.

I just ran it about 1,000 miles after swapping in a new cam and driving 70-75 I returned about 13 miles per gallon. It gets better the slower you drive but if you are using it like it should it's not terrible.