400 sbc, good?

[starterguy]

I was approached by a good friend about aquireing a 400 sbc. It is currently a good running stocker,I plan to install in my 67 Nova. My question is how good are the stock blocks really?
I have heard a million stories good and bad, mostly bad though about their fragile(?) bottom ends. Namely mains that crack and self destruct upon putting some reasonable power to them. This will be the long term motor for the Nova if its good, I eventually want to make about 450 hp with it and flog it at the track on occasion.
So are they good or are there specific blocks I should look for as opposed to any ol 400.

[Barry Donovan]

they push boundaries badly.

I did not forget the freak 400s that came in vans running forever..they must have gotten something good under the doghouse.

my bro n laws nightmare revealed errors in every direction.

go for gigantic radiator, keep it stock.

[Scott Liggett]

The four bolt main 400's aren't great. But they are hard to find anyways. My friend has a 550 hp 406 in Scout. You can build one up to 420 ci no problem. I want a 400 block.

[kyhunter89]

The main webs crack on the 4 bolt mains. The 509s are the sought after 2 bolts, aswell as others iirc., the 2 bolt mains are still fine for most builds.

[jays67]

I have a few the one in my 67 is a two bolt with splayed caps and is poked and troked to 440 the one for our race car is over 500 hp and is a 408 my one 4 4bolt is only punched to a 406 has a good cam and decent head (not great but ok) and it seems like a giant killer I like them but I also like 283's lol

if it has 3 soft plugs on eather side it is a 4 bolt if it has 2 with a un drilled pad for the 3rd it is a 2 bolt
if it runs good now with a good cam and nice heads ,intake and a clean up bore your nova would be an animal!

[MadmanMark]

I think the big 400 issue is they were intended to move big heavy stuff more so than for performance, and there can be a lot of variability block to block since tolerances weren't tightly controlled. I remember working with an engine guy in the mid 80s and he had a bunch of 400 blocks, and only 1 of them he felt was suitable for the planned 450hp build (a 2 bolt that was machined for 4 bolt caps). On the plus side, that motor is still running and hasn't ever been apart.

[SpiderGearsMan]

had a 70 400 in a 79 mailbu , ran like an animal with an m21 4 speed

[STINEY]

This thread is just in time, I recently brought home a 400 that is supposed to run..... you know that drill don'tcha? Got it cheap enough to not matter in any case, if nothing else the crank may be useful.

[A/Fuel]

I've seen plenty of cam, intake, headers, ect, 400's run good for a long time. I had one in a '78 Blazer that would smoke the front and back tires.

[TC]

I have a stock 2 bolt(509) block in the 406 in my '71 Camaro, which is basically the only GM part of the motor......The trick is to get the two bolt block and put spayed caps on it and put a 5.7 or 6 inch rod in it.......

I believe Smokey(not the southwest sales rep) said that if GM would have put a 5.7 rod in the 400 that it would have been the ultimate production small block........

[starterguy]

Thanks for all the advice, I am going to check if it's a 509 casting and if it is then I will scoop it up. It's good to have you guys to ask because for as many locals as I know around here, nobody actually seems to run them. One guy did a few years ago, made a 421 and it ran well but it was the only one.

[SuperBuickGuy]

The 400s biggest problem is the siamesed cylinders - if you have a boosted application, the head gasket between the middle cylinders overheats and burns out.... it's why you build a 383 rather than a 400 based motor. However, 400s, if built for torque, are flat-out awesome.

[STINEY]

However, 400s, if built for torque, are flat-out awesome.

Any hints on the magical torque formulae for 400s?

[65RHDEER]

Any hints on the magical torque formulae for 400s?

Here is one that Chev Hi Per did in 2003 using Vortec heads, I've been collecting parts ever since and one day...

http://www.chevyhiperformance.com/techarticles/148_0306_chevrolet_406_big_block_torque/index.html

[TC]

The 400s biggest problem is the siamesed cylinders - if you have a boosted application, the head gasket between the middle cylinders overheats and burns out.... it's why you build a 383 rather than a 400 based motor. However, 400s, if built for torque, are flat-out awesome.

This is pure myth........I guess aftermarket Dart Blocks with Siamesed cylinders are crap to.......

The fix is to run copper head gaskets and O-rings.....Or now a days with the advancement in cylinder head gaskets you can run one of these SCE ICS Titan copper self-sealing head gaskets, these are the head gaskets with the steel rings molded into the head gasket around the combustion chambers.....