how much?

[tscott9330]

How much should I expest to pay for a good chevy 400 core?

and , How hard are they to find?

Tom

 

[tscott9330]

Also I know that gm put the 400 in pontiacs and some of their other makes, but were the block identical or are there differences in the blocks?

Tom

 

[Thumper]

The 400 Pontiac was specific to Pontiac. It was a big block that came in different cubic inch configurations depending upon bore and stroke ranging from 326 cubic inch to 455 cubic inch sizes. GM discontinued this engine in 1978, but sold the remaining inventory thru the 1979 model year in the Trans Am with a 4 speed only. Great motors, extremely torquey, not high rev engines without spending big bucks. Their weak spot was the connecting rods.

 

[phxraptor]

I was looking for a 400 block for a 406 build. Have decided to go the crate route. Any way I found some short blocks at core supply places for any where from $150-$250 and up. Hope this helps.

 

[tscott9330]

I just got a quote from a company in illinois for a 400 4 BOLT main. with shipping its gonna be $400 total and he guarentees no cracks. I'm gonna do a little shopping here in florida and see if I can find a better deal from a local salvage yard. Anyone want to recomend a reputable salvage yard in the Orlando area?

Tom

 

[robert kirk]

Depending on what kind of motor you are building, a 2 bolt is stronger than a 4 bolt. The main webing in the 2 bolt is thicker, installing splayed caps and having the block line bored will make it almost bullet proof. Watch the timing as to much will push the bottomend out. Also chevy had a problem with core shift in the 400 blocks, If you plan on punching it out over 30 it is a good idea to have cylinder wall thickness checked. Its a bummer to spend money building a motor only to find out it overheats bad and nothing you do short of sleeving a cylinder will fix it. I learned this the hard way. just my opi robert

 

[tscott9330]

that is the opposite of what i've always heard, I was always told a 4 bolt is what i need for high hp/torque motors. Is this just a condition faced by 400's or are you saying that a 2 bolt is stronger in every motor?

Tom

 

[Robin7TFour]

tom, i have been reading alot of good things about the 383 motors. its easier to find a donor 350 and build. also a 400 will be limited on its total bore, due to thin water jacketing.
you can use a two bolt main. they are capable of handling up to 500 hp if the proper hardware is used..

just a few random thoughts

robin

 

[robert kirk]

The webing in the 2 bolt is thicker. You can then install steel caps, 4 or 6 bolt pattern and have the block linebored. How many bolts hold the main caps on in a street motor is not as important as the quality of the bolts or studs used. This is not the place to try and save a dollar. This is about as strong as you can get a factory production block. You can fill the lower part of the block, that will add considerable to the stability of the webing, and increase center line strength. The down side is street motors tend to run hot with half the water jacket in the block filled. Unless you are planing to have extreme cylinder pressures, this is overkill for a street motor. Also look for blocks that have 010 cast in the side. This does not mean its .010 over bore, it indacates the nickle content of the casting. just my opi robert

 

[tscott9330]

am I really gonna have problems with a 400 or so hp motor if I get the 2 or 4 bolt main? I always use ARP bolts on everything. This motor is not going to see rpm's above 6500 and i would be suprised if it saw that.

Tom

 

[robert kirk]

A 400 hp motor will be just fine a factory 2 or 4 bolt. Don't shy away from a good deal on a 2 bolt block it will handle 400 hp easy. At that level a new cast crank, stock rods, and cast pistons, will also be fine. They do need to be balanced and the clerances set up properly. Also the stock oiling system is excelent don't screw with it. You don't need a high volume pump or a high pressure punp, it will just suck your pan dry and scar bearings, they also increase load on the distribitor. If funds are ava, forged pistons are a very good investment. It would let you put a small shot of nitros onit at a later date with outcausing problems. hope this helps, robert

 

[MaineShark]

On the 350 block, 4-bolt mains are superior.

On the 400 block, 2-bolt mains are superior.

Or, to put it another way, you couldn't give me a 4-bolt 400 block. I've heard too many "cracked block" horror stories. The extra bolts go into places that they shouldn't...

Joe

 

[tscott9330]

ok then , hees another one for you all. what accessory mounting brackets does the 400 use? Are they 400 specific or does it share them with the 350?

Tom

 

[MaineShark]

Same brackets, same intake, same oil pan, same exhaust manifolds, same motor mounts. The only major external differences are the harmonic damper and the flexplate. And not even those, if you go with an internally-balanced crank, which will work with the 350 damper and flexplate.

 

[tscott9330]

this sounds good, but where is all this added expense that I have been hearing of? So far it is going to cost about the same as my 383 was going to but it will have better parts. But maybe i'm just starting off with more knowledge this time and so I'm a little more savvy.



Tom

 

[MaineShark]

where is all this added expense that I have been hearing of?

For starters, the 400 blocks are more expensive than the 350 blocks, due to their rarity (well, in comparison to the ever-present 350, anyway). You also end up needing to buy a new harmonic damper and flexplate designed for the 400 crank, so that's a potential expense (depending on whether your originals were in reuseable condition).

And then there are the intake, heads, and exhaust. Since larger displacement means more airflow, you need somewhat better-flowing parts, to obtain the same level of efficiency.

Joe