how the hell can you thell a 400 from a 350


thx

The balancer is quite different and the 400 has 3 freeze plugs on the side of the block instead of two.

Rene

thanks but what about other small blocks

like dont they have a number stamped somwhere

for example international stamps the size on a mechened surface on the rite side of the block g like tis

http://www.binderbulletin.org/images/idboss.jpg

They don't stamp the displacement on them like that. That would be too easy. There is a number stamped on a pad on the block deck surface that sticks out in front of the passenger side head. This number can be decoded to ID the engine. http://www.nastyz28.com has a listing of the suffix codes (last 2 or 3 letters of the block ID #).

The 400 will have bulges in the water jackets around each cylinder, by the freese plugs. And three freese plugs. Sometime only two freese plugs. But you can see the casting spot where the third center one should have gone.

www.mortec.com is another good site for decoding sbc casting numbers.

The numbers are on a machined surface at the front passenger side of the block. It should be visible with the alternator removed but can be seen behind and below the alt if the area is cleaned.

Rene

Another way is to look at the block - all the 400's I've seen have the numbers 509 cast into the main section of the block.

Actually, now that I think about it, if you are trying to ID the motor in a junk yard, the casting number on the block will be the easiest way. The casting number is on the horizontal surface just above the bell housing on the drivers side back of the block. 400s will be one of:
330817 - '73 - '80 2 bolt
3030817 - '73 - '76 2 bolt
3951509 - '73 - '80 2 bolt
3951511 - '70 - '73 4 bolt

Most people agree that the 2 bolt 400 blocks are stronger and more desirable than the 4 bolts.

the numbers on front passside off block tells year and car or truck where it was made. the actual id pad is on the back driverside of the motor I grew up in the chevy 350 plant in michigan and stamped a few motors

The number of frost plugs is a bad idea - came either way.

Casting numbers are good - but can be tough to get off a gooey engine that's still in the truck.

The balancer is a pretty easy check. The back of it looks like somebody zipped around half the circumference with a 1/2" radius quarter-round router bit. You can even check for this by feel on the darkest stormiest night ;)

i got 426 inchers out of my old 400. and think they were bad ass motors! but theres no replacment for more displacment. go with an 800 inch merlin!!!!!!!