400 big block

The 400 is a great engine for a lot of reasons.

Big bore helps not to shroud the valves.
Very strong engine blocks.
In fact they are the strongest stock block ever made outside the hemi.
Low deck is easy to live with in a tight a body.
Great rod ratio.
For example:
A 318 and 340 have a 6.123 rod and a 3.31 stroke.
By dividing 6.123 by 3.31 you get a rod ratio of 1.84.
The 400 has a 6.358 rod and a 3.38 stroke.
By dividing 6.358 by 3.38 you get a rod ratio of 1.88.
What this all comes down to is piston speed.
A better rod ratio lets the piston move at a slower speed, due to the rod staying closer to the center of the bore when moving with the crank.
How much slower???

Well, a 512 stroker has a piston speed of 5250 ft/min at 7000 rpms.

A 400 can be twisted up all the way to 9000 rpms and still only have a piston speed of 5070 ft/min.

At 7000 rpms it's 3943 ft/min.
It really is a big block screamer.
Give it compression and a good cam and it will work great.

I just bought one in the fall---- built to stock specs(1973)low comp.8.1
This man and his son built it over ten years ago with all the machine work done by napa.
They threw it on a brand new engine stand and never used it.
It came out of a 1973 charger from what i was told.
I guess the charger hit a pole side ways and was toasted.
Anyways......They spent a little over two grand.
I got the hole engine and stand,plus a 727 transmission, plus a 650 holley all for $300 bucks.
I do everything on a budget and it's nice to get lucky once in a while.
It will take some time to get all the parts i need.
I just bought the new victor single plain intake and it's a nice piece.

I think the 400 is a great engine.
The 400 engine i got is stamped with a hp.
From what i read ,it has a premium cast crank in it.
It's suppose to have a different part # then a standard cast crank.
Is it any better???We will see when i crack it open.
It should with porting the heads and the right cam and compression be near the high 475 to 500 horse mark.
The only thing is if i go to aluminum heads down the road will i exceed the cast cranks strength?
500 horse seems to be the max on a cast crank according to a few sources.
Well i could always flip it over and install a steel forged crank right???
I will be lucky to be able to buy a set of good headers and a radiator without loosing my mind.

Sometimes i respond to stuff here and get a little crazy with the keys.
good luck :thumbup: mopar7172.

PS If the engine runs good and you can't swing a rebuild, run a small performance cam in it with some new valve springs and seals installed on the heads.