I am trying to put a motor "together" for motivation (myself and the car) out of parts that I have, as Im starting over for the 2nd time in as many yrs (plant clossings)money is non existent. What I do have is a 383 that looks fairly clean but is unknown. .020" deck with 10cc dish-almost entire piston. I also have a 400 that has been rebuilt with L3014F Flat top .030" over pistons but, with a .120" deck. I have a set of 915 with 79/80 cc. this +.018 HG will give the 383 +/- 9.0 and the 400 +/- 8.3
For parts I have an DP4B Dual plain, xe274h comp, also a I-.440"/E-.470" cam, 3 way timing sprocket,isky adj 1.5 rockers, 1 7/8" header, or HiPo manifolds,windage tray, elec ign. Going into a 69 RR POST 4spd car. 3.55 or 3.23 posi.
Would I be better to go for the 383's higher comp. or the fresh 22 extra cubes of the 405? Im leaning to the 400 because it is some what fresh, if it where a 440 at 8.3 there would be no question I would go for the cubes but, is 22 enough to make up for the comp of the 383? what are your thoughts? I had something close onetime 400, milled 906, Engle K7HYD .517" 244@50 ran cam adv.same header, intake,700DP auto,stock conv. 3.23 in a 68 GTX. ran like a scalled dog. weld:

Mr.Runum.

You may wish to cosider which engine has the most parts available for future builds. Much easier to find kits/pistons for a 400. I think that the walls may be thicker too.

I have 3 other 400's and 2 440's(apart needing rebuilt) and if this is the way I go for now i will sell the 383. The future will 472, 3.9 stroke, stealth heads, ect. Right now I just want the most Bang for my buck. Going to drive it like I stole it.

Mr.Runum

go with the 400. 17 more cubes, it is rebuilt, both have no quench. Then put together a good 400/440 built properly(proper quench & CR etc).

The 400 is the way to go!!! More cubes more parts.

THE REAL big diff between 383 and 400 is just the compression due the piston height. In stock form, 383 is a NO DOUBT, WAY TO GO, but with mods, 400 have more juice to get of course.

Beside the higher compression ready to get more HPs and torque, then you'll find easilly 383 with forged cranks, and 400 are allmost all with cast cranks, but you can interchange it anytime to fit a 383 crank on to a 400.

an advantage on 400s on stock form is the manifold ready to get a spreadbore carb

The 400 with the cam/heads/intake would be a good basis for a turbo or supercharged engine

Yes it would be but,,,what I am looking for with using either short block as is..with the parts I have listed...Which is going to make the best HP? With the 400 being .030 over to 405cid and running the cam advanced, every thing else being equal will the bigger 405 with 8.3comp suck more air, make more HP than the 383 at 9 comp? Anyone have a computer program for HP? plug in the #'s and see.

Mr.Runum

The 400 is basiaclly like a bored 383. We run a 400 in my boys Dart thats a street car he drives to the track like me. Nothing fancy as it runs a MP .557 cam and Eddy heads with 10.6 comp. Its a stock body 72 Dart that has run 11.40's @ 117 with 3.91's and Hoosier QTP tires. And he spanked this Vette also. Ron