400 sbc, good?

[JeffMcKC]

I have one ran the Hell out of it. Money needed for ( If you going to run it hard mine was over 700 HP)

Sonic checking the cylinder walls first
Squaring the block
Line up the lifter bore and Brass lined ( Huge issue on the blocks )
Head bolts got to go and studs used the 400 Blocks wont hold good Torque.
Line Bore with a 2 bolt block adding Splayed Caps and straping the front one
receaver groove the block to hold the gaskets
the Block alone will give over 50 HP up in the cylinder walls not sealing to the rings dont go more than a 420 and over a 5.85 rod

If it was me I would get a SHP and build from that they are not ready out of the box to build

[yannick]

pop for a new dart shp block ................1,320 bucks does not sound too bad

Worth it, considering how much you can put in a stock block...
Stock 2 bolts are fine though. I found they last quite a bit longer if you stud the mains, run a steel crank and long rods 5.7+ when you get in the 500-600 hp range, anything more invest in a race block!!

[SpiderGearsMan]

pop for a new dart shp block ................1,320 bucks does not sound too bad

[TC]

I wouldn't worry about the casting number. If the block is in good condition, get it. If the bottom end is built wisely, you shouldn't have any problems with it at your 450hp goal.

If it is already bored .030 oversized and needs to be bored again to clean it up - that's when you need to get finicky. I wouldn't pay much more than scrap price for such a block.
Regardless, have the machine shop sonic check the cylinder walls to be sure they are thick enough to build a motor safely. <-- I don't know what the magic number is for cylinder wall thickness, but the machine shop should. Perhaps some people here can offer their advice in case your machine shop is more interested in making money than being honorable.

Don't be afraid of a 400 or 406 - I would put one in every "toy" I ever own.

.030 is all I would go on a stock 400 block, you can go as much as .060 but you better have a good cooling system, because the wall thickness gets pretty thin at that point......Also most shops will sonic test the block to make sure a .060 over bore is possible........

[yellomalibu]

I wouldn't worry about the casting number. If the block is in good condition, get it. If the bottom end is built wisely, you shouldn't have any problems with it at your 450hp goal.

If it is already bored .030 oversized and needs to be bored again to clean it up - that's when you need to get finicky. I wouldn't pay much more than scrap price for such a block.
Regardless, have the machine shop sonic check the cylinder walls to be sure they are thick enough to build a motor safely. <-- I don't know what the magic number is for cylinder wall thickness, but the machine shop should. Perhaps some people here can offer their advice in case your machine shop is more interested in making money than being honorable.

Don't be afraid of a 400 or 406 - I would put one in every "toy" I ever own.

[TC]

The problem is more than just a narrow area between cylinders, it's that the siamese portion of the cylinder walls is getting zero coolant, just heat from the other cylinder next door. Don't you think it's a good idea to have coolant running along the other side of all cylinder suraces? I kinda do.

Siamese bores do work...the Hemi in the avatar has 'em and has never had a problem...but I wouldn't use such a block in something I needed to be street-durable when there is the conventional alternative available.

I understand what your saying about the coolant, I'm just saying people have been using 400 blocks for years with no problems, hell GM even put them in Trucks...........I always looked at a block with Siamesed cylinders as being stronger since all the cylinders are connected........

[Loren]

The problem is more than just a narrow area between cylinders, it's that the siamese portion of the cylinder walls is getting zero coolant, just heat from the other cylinder next door. Don't you think it's a good idea to have coolant running along the other side of all cylinder suraces? I kinda do.

Siamese bores do work...the Hemi in the avatar has 'em and has never had a problem...but I wouldn't use such a block in something I needed to be street-durable when there is the conventional alternative available.

[TC]

Also all you guys that are saying these motors don't make power are Crazy, I have a few friends running 400's and they spin them 8000rpm..........

Hell my 406 will make over 600hp and peak hp should come in around 6700rpm......

[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.....

[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

[STINEY]

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

Any hints on the magical torque formulae for 400s?

[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.

[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.

[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........

[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.