hello guys need a tip, i got my friends father thats selling a 400 block ...I wanna know is it a big block or small block ? Can it withstand more same or longer than a 350 can?And will it fit into a 1991 z28 5.7 350to 400 swap? if so what kind of transmission should i look into?Or even better what will be a good affordable performance to put into the 400 ...Example : forged diamonds pistons camshaft etc...Any info on that will be great ..Give me your opining on the modifications i should put into the 400 while its half way built?

1 more thing a 350 stock engine brings 245 or 275 hp, How mush does a 400 block bring to the table Thanks...

 

The 305-350-400 were all based on the same block ...
It will accept any trans a 350 would.

You can swap over the 350's heads if you'd like, just have them drilled for steam holes.

Power levels depend on the build up.

 

It could be either. Need more details to know for sure.

 

look at the space between the exhaust ports on the heads.
If the space is equal from one port to the other, its a big block.

 

chevy?
396 bored .030 = 402, not 400...unless chevy only bored it .020 in some years??(big block talk)

Its most likely a sbc (small block chevy).. and when it all comes down power, your power comes from whatever u put in it..

also, Spectre, I am assuming you mean that 305-350-400 are all small blocks.. cause it isnt like you can bore out a 305 to 4"...

 

They all have the same external dimension because they were based on the same block.

I didnt say you could turn on into the other.

 

just making sure, lol.. the sad thing is, i KNOW ppl who say that...

 

Chances are it's a SBC. The 402 BBC was actually called a 400 by GM and it caused a lot of confusion until they rebadged it as a 402. All they did was punch out a 396 .030 over to get that size.

As mentioned above, if you can't distinguish between a BBC and a SBC, just look at the exhaust ports. SBC center 2 exhaust ports are siamesed. BBC exhaust ports are all equally spaced apart.

BBC also has a wider valve cover which is easy to see.

As for compatablity between a 350 and a 400 SBC, they're externally the same size but there are a few differences that doesn't make it a 100% bolt in swap.

The 400 is externally balanced. That means it needs a special balancer and flexplate/flywheel. Depending what tranny you want to use behind the engine, the proper flexplate/flywheel will be needed.

Everything else that you can buy to hop up a 350 will work on the 400. Your 91's intake won't be a direct swap if you wanted to use it. The angle of the intake bolts is different.

Comparing apples to apples, the 400 will make a bit more power than the 350. The slightly bigger bore will make a bit more HP and the longer stroke will make a bit more torque. That's providing the same cam, heads, induction is used on both.

400's were never a performance engine from the factory. They all had cast cranks. A few had 4 bolt mains but these are considered the weaker blocks. They were all low compression smog engines. The last 400 was produced in 1979 so the factory blocks are getting hard to find.

 

.031", actually.

396 bore was 4.094, the "400" or "402" was 4.125".

I don't recall that any BBC 402 badge actually said "402". They were all 400 that I saw.

At any rate, we need the "straight" scoop. Find out exactly what he has.

 

Let's not discount the possibility that this is a Pontiac 400.

 

hmm, everything i read says they were still badged as a 396 because of the recognition and insurance purposes

 

yah.. im looking for a 4bolt block myself.. i really dont wanna get a 2bolt, get splayed maincaps, and get a line-hone... thats a good $500 at least , plus the cost of the block

and anyway, were pontiac 400's any type of power makers?

 

2 bolt 400 blocks are stronger than factory 4 bolt blocks.

 

could a 2bolt 400 block with a stud kit be strong enough to take about around 500tq?

sorry to hijack this, last question, i promise

 

There are two "chevy 400" engines... one is the 400 small block, and theres also the 396/402 big block, which was also badged as a 400 big block.

 

Some of the early 70's pickup trucks have 402 badges on them.

The 400 4 bolt blocks are weaker because the crank has larger journals. This means the webbing for the mains is smaller. Add a second set of main bolts and there isn't a lot of metal left around them.

A studded 2 bolt main is far superior to the 4 bolt main 400 block. 500 HP could easily be taken. I'm not too sure about the cast crank though.

See if you can get a casting number. 509 is the most popular 400 block.

 

dont worry, forged and not twisted all the way

 

i looked like crazy.. all i can find is 396 badging (camaro/chevelle), no 400 or 402

 

Canadian 402's may have gotten "402" badges.

 

Actually, the only "true" 396, was 1965... and IIRC, only the Corvette and maybe full size Chevys got that.

After that, they were all technically 402s because of the bigger bore.

GM still called it a 396 though, because the numpties that ran GM decided that mid-size cars (ie. Camaros, Chevelles, etc) could not have engines bigger than 400ci. The 402 big block would be breaking this rule, so they called it a 396. The exception to the rule, as usual, was the Corvette.

This is also why, on paper, the 396 was the biggest engine you could get in a Camaro from '67-69, but in reality the biggest was the 427. The 427 cars were special order cars that the 'car guys' at GM kept as a dirty little secret from GM execs that banned anything bigger than a 400ci in those cars.

Just a little trivia for you

 

Oh, come on - 1966, 1967, 1968 & 1969 were all 396's, regardless of what body it went into. 1970 saw the advent of the 402, and the 396 as a displacement no longer existed, regardless of badging. Same year the 400 SBC came out.

Actually, that probably had more to do with the .031" punch-out than anything else - after all, the BBC's all have to be bigger than the SBC's, right? (trucks not withstanding...)

Don't forget, the 396 was developed as a result of a rumor that NASCAR was going to limit cubes to that weird number - which is how the 396 got its weird bore size.

I still say it could be a Pontiac 400...

Hey, where's Mr. straight been through all this?

 

I think you're right

 

thats what im wondering.. and i still cant find 400 (to represent BB) badging... lol

 

Try looking for 400 and 402 crossed-flags air cleaner decals, there are lots around.

 

thanks guys for reply...Noted...I have a fresh new problem (annoying) My camaro has lost some power due to msd unplug but thats not the problem the real missing power is when im at a stop or red light even while driving sometimes...We i take off my shifter give a "KICK" Example: Gaz ....Bang! even when its shifts it give a small kick but the big kick is when im stop then push the gaz...When i push more than half it kicks when i barely push its ok..Fells like the drivetrain is lose or something ...cause when i hit medium size pot holes you hear something under the car bounce around i did a basic check to see if any lose NOTHING!!????Was told by a old friend its "KICK DOWN SHIFT" ?? was it that anyway..
Ive lost power because of this kick ive never had a Civic come that close to my rear end before...Thanks in advance..

P.S, its a 4 speed auto (OD)