SBC 400's cubic incher...any good?

[gearheadperkins]

I have a 400sbc in my 72, and it has been in there for the last 16ish years.. no issues and plenty of tq... I love it..

[midniteblues]

I found a 400 in the jy with just under 70k on it. Got it for $175.
Stripped it down cleaned it up,put on a few aftermarket parts and plopped it into my k 20 with most of the oe dressings. It was a hard decision too keep the rams horns instead of headers.

I'm way happy I found that motor it's certainly not AS torquey as my bbc but I would say it's rite in line if not more torque than my slightly worked 355 but at way different rpms.

Without going BBC, it's exactly what a big heavy k20 needed.

[Boog]

Originally Posted by truckster

You wouldn't be disappointed with it. Just remember it's externally balanced, but everything else bolts up.

Shoot. I’d leave the 350 in it while i freshen up that 400, swap em out and never look back.

[Coley]

damn.....you guys are killing me here, lol.
I'm torn to go get that darn thing....
Although 'today'....I have no need for it given the way my truck is currently running which is very nice.....but its going to need renewal within a couple of years I think.

Coley

[Boog]

Well we are your support group bud.
When are ya leaving?

[BossHogg69]

Originally Posted by Coley

damn.....you guys are killing me here, lol.
I'm torn to go get that darn thing....
Although 'today'....I have no need for it given the way my truck is currently running which is very nice.....but its going to need renewal within a couple of years I think.

Coley

Says the guy who has FOUR trucks in his signature!!!! You only 'need' one! Get the 400!

[truckster]

Originally Posted by Boog

Shoot. I’d leave the 350 in it while i freshen up that 400, swap em out and never look back.

I would probably do the same.

[garyd1961]

Originally Posted by B. W.

If you think about it, the 383 is a 400 with a smaller bore. If I had a choice between the two I'd run the 400.

Wrong, totally different blocks. The SBC 400 as someone has already said have problems with cooling. If you bore it out it has worse problems with cooling. I would go with a 350 block , you can always machine it and put a 383 crank in it if you want more cubes.

[truckster]

Originally Posted by garyd1961

Wrong, totally different blocks. The SBC 400 as someone has already said have problems with cooling. If you bore it out it has worse problems with cooling. I would go with a 350 block , you can always machine it and put a 383 crank in it if you want more cubes.

Plenty of 400 SBCs have run for decades without cooling problems. You need to have the steam holes in the heads and have a cooling system that works as it's supposed to.

[kwmech]

Originally Posted by garyd1961

Wrong, totally different blocks. The SBC 400 as someone has already said have problems with cooling. If you bore it out it has worse problems with cooling. I would go with a 350 block , you can always machine it and put a 383 crank in it if you want more cubes.

BUT, you cannot take out the 350 block to 4.125+. The only cooling problems I've really seen with a stock 400 is lack of maintenance with the cooling system. Dirty and partially plugged radiator immediately comes to mind. I've never had an overheat problem with any of the 400s I've had

[davischevy]

Originally Posted by Coley

damn.....you guys are killing me here, lol.
I'm torn to go get that darn thing....
Although 'today'....I have no need for it given the way my truck is currently running which is very nice.....but its going to need renewal within a couple of years I think.

Coley

If we only bought things because we "NEED" them, we wouldn't be on this site.

Besides this gives you two years to build it. I'd say that makes you a good planner. Yeah, that's it, a good planner.

[53chevyforever]

Originally Posted by Coley

damn.....you guys are killing me here, lol.
I'm torn to go get that darn thing....
Although 'today'....I have no need for it given the way my truck is currently running which is very nice.....but its going to need renewal within a couple of years I think.

Coley

My vote is the 400...I have run them since 1970....as long as your cooling system is good...no problems...here is an example for you...drive something with a 305....then drive the 350...quite a difference in power and torque....the 400 is that much stronger over the 350. Here is a pic of my 400 bored .030 which is 406....scat crank and 5.7 eagle rods and keith black dished pistons and vortec heads...around 9.1 compression. I will be dropping this in my 66 c10 with a 700r4 and 3.73 gears very soon. Run the 400 you will not be disappointed.

[Coley]

Quick question:
What is the externally balanced thing?....is this something to watch for or a problem or?

Coley

[Boog]

That's what I'm sayin. Just like that.
That's a sweet combo for your 66.

[davischevy]

Here is some reading material.

http://www.hotrod.com/articles/ccrp-...l-block-chevy/

[truckster]

Originally Posted by Coley

Quick question:
What is the externally balanced thing?....is this something to watch for or a problem or?

Coley

All other SBCs have internally balanced crankshafts. The 400 is externally balanced, which means the flywheel or flex plate will have counterweights to balance the rotating assembly. You'll just need to make sure you have a flex plate or flywheel that's for a SBC 400. If you don't you'll have a crazy vibration.

[midniteblues]

A harmonic damper and fly wheel/flex plate is what's needed
If it don't already have these.

Also I had to drill and tap the block on my 400 for the clutch ball stud since 99% or all of them were automatics.

[special-K]

Originally Posted by garyd1961

Wrong, totally different blocks. The SBC 400 as someone has already said have problems with cooling. If you bore it out it has worse problems with cooling. I would go with a 350 block , you can always machine it and put a 383 crank in it if you want more cubes.

Wrong. That 383 crank (and rods) is a 400 crank. He never said the blocks were the same. The comparison is in the rotating assembly. No need to bore one out since it's already 17 cubic inches bigger than a 383. Yeah yeah, if the motor wears and needs rebuilt one day they don't take over boring as well. But plenty running around not needing that and they don't run hot. I don't think a 350 block can take the 400's bore either. Isn't the 383 max bore in a 350 with 400 crank?

[truckster]

The possibility exists that you might run into a 400 block that shouldn't be overbored, but I personally haven't ever seen one that wouldn't take .030 and be healthy. A .030 overbore gives you 406 cubic inches, and there are a lot of those around.

The whole reason the 383 became popular was a scarcity of 400 blocks. Given the choice between the two, everything else being equal, I would take the 400 any day.

[68Gold/white]

Originally Posted by Coley

Quick question:
What is the externally balanced thing?....is this something to watch for or a problem or?

Coley

If you look closely at the picture before this post, you can see the balancer looks like part of it is ground away (I call it a scallop). THis identifies a 400 or 383, unless a LOT of money has been spent to internally balance them, (a very unusual thing...especially for a street engine).

400 flex plates will have an obvious weight on them , AND a dowel pin in the crank. THe dowel pin also identifies the crank as a 400 crank, and the pin is part of the balance of the crank.

The problems folks have with 400's are almost always a lack of maintenance, inept engine builders or improper parts. There's no real big mystery, just big power potential if you get everything done correctly!!!

My buddies 66 C10 would absolutely rip your head off. Tha build sounds sooo lame, it was awesome. He had a weak moment and sold that pickup around 1995, long story I didn't know about it, or I would have bought it. No telling where it is now.

[jus2qwk]

I love all the 400ci ive had. currently I have a 406, big solid lift cam, aluminum heads and intake. one key to making them really run is to change the rods and pistons. stock the 400 has a short rod and a tall piston. this combo is ideal for a good performer because the rod is trying to push the piston into the cylinder wall. from my experience if you go to a 5.7 rod or a 6.0 rod it really help. the longer rod straightens the piston out in the cylinder. the first engine I built I used a good set of used rods, new pistons, 041 heads and that thing was a lot of fun for real cheap. pulls way better than a 350 of similar spec. use a 4 core radiator if you can. i've never had any cooling issues

[bandit0067]

Are the rods on a 400 a bit shorter than other small blocks.....

[68Gold/white]

Originally Posted by bandit0067

Are the rods on a 400 a bit shorter than other small blocks.....

Yes, 5.565. all other small blocks 5.70

Longer rods are always better. A street engine doesn't really need all the fancy hot rod engineering, usually.

[garyd1961]

Originally Posted by special-K

Wrong. That 383 crank (and rods) is a 400 crank. He never said the blocks were the same. The comparison is in the rotating assembly. No need to bore one out since it's already 17 cubic inches bigger than a 383. Yeah yeah, if the motor wears and needs rebuilt one day they don't take over boring as well. But plenty running around not needing that and they don't run hot. I don't think a 350 block can take the 400's bore either. Isn't the 383 max bore in a 350 with 400 crank?

OK, I get what you meant now. I was referring to after market cranks built specifically for the 383 instead of a factory 400 crank.
Just for what it's worth my cousin recently took out a fresh built 400 because of heating problems. But I just learned the 350 he put in is having the same problem so I don't think it was the motor.
I keep telling him he need to put a by-pass hose from his intake to his water pump but he wont listen. The heater is usually the by-pass but if you do away with the heater you still need to run a by-pass hose so the water can flow through the heads. That will cure a lot of heating problems on these motors.

[GASoline71]

Originally Posted by davepl

One thing I've never been able to figure out though:

People take 400s and put 350 cranks in them and make 377s.
People take 350s and put 400 cranks in them and make 383s.

Why would the 377 be preferable over the 400? Why destroke it? I know it would improve the rod ratio, but in terms of perf, maybe piston dwell is different? I don't get it, like I said...

A properly built 377 will spin up quick like a 283. Great circle track engines!

Originally Posted by garyd1961

OK, I get what you meant now. I was referring to after market cranks built specifically for the 383 instead of a factory 400 crank.
Just for what it's worth my cousin recently took out a fresh built 400 because of heating problems. But I just learned the 350 he put in is having the same problem so I don't think it was the motor.
I keep telling him he need to put a by-pass hose from his intake to his water pump but he wont listen. The heater is usually the by-pass but if you do away with the heater you still need to run a by-pass hose so the water can flow through the heads. That will cure a lot of heating problems on these motors.

If any cylinder head other than a head made for 400 SBC's will have to have steam holes drilled in them to work properly on a 400 block. Maybe your buddy had 350 heads that were not drilled for a 400.

Gary