What kind of horsepower can you get from a 1975' 440 motor?

[440charger68]

     For Christmas my dad gave me a 1975 440 motor, the guy my dad bought it from said it is rebuilt and should put out 550hp depending on what carburetor you put on. But i thought that the 1975 440 motor were very low compression and very low performance motors. The motor has been bored .30 over, block was  honed, crank balanced within a gram, forged pistons, and a purple cam. The heads have been resurfaced and the valves re-seated, also has high compression valve springs, Edelbrock high rise intake manifold with a holley 770 cfm carb. What kind of horse power should i expect from this? I believe 550hp is a little far fetched, and i'm just shooting for 375hp. 

[RD]

it totally matters on the pistons he put in there, the cam grind, and what the heads will flow.  you find that out.. and you will have your answer.

I had a 10.75 to 1 440 with a .509 cam, and dual 600 eddys and it pushed me to low 12's in the quarter with a terrible rear suspension.

purple cams are really not as crappy as people think, there are just better alternatives on the market nowadays.

[SeattleCharger]

a stock hp 440 in an original R/T Charger was 375, a stock 440 was 325,  if your motor is built you gotta be above 375, in the 500's I would say would be hard to do without aluminum heads, but depends on the cam and the headwork, 450 seems possible,  if it has good head work and good cam, purple cams aren't bad,      pretty cool dad you got there

[firefighter3931]

   But i thought that the 1975 440 motor were very low compression and very low performance motors.

They were....late 440's usually had less than 8:1 static compression. 

The motor has been bored .30 over, block was honed, crank balanced within a gram, forged pistons, and a purple cam. The heads have been resurfaced and the valves re-seated, also has high compression valve springs, Edelbrock high rise intake manifold with a holley 770 cfm carb. What kind of horse power should i expect from this? I believe 550hp is a little far fetched, and i'm just shooting for 375hp.

The 550hp number is a little far fetched unless the heads were heavily ported and it was running a lot of compression and a roller cam....but that doesn't sound like this motor. 


From what you are describing this is more of a 425hp type build depending on the cam profile and it will want a set of headers for best performance. This should be a good street motor with a bit of tuning and the right components to go along with the engine build. Try and find out the cam specs....then the proper axle ratio and stall speed can be determined. 


Very nice gift ! 



Ron

[440charger68]

  Thanks, you guys are a lot of help.

[Nacho-RT74]

with right parts you can get same juice than any other earlier Mopar motor

[440charger68]

whats the difference anyway between the 60's 440 motors and the later 70's 440 motors?

[Nacho-RT74]

there is some diff on block about casting, some reinforcements etc... there is a thread about that somewhere. Now about internal, piston height is basically the diff.

Also heads, but mostly sure you'll gte one of the most desireable ( 452s ). Cast crank instead forged. but the basic specs and meausres are the same. Same Bore, same stroke etc...

So to you get an erlier 440 specs powerplant will ned basically just get the earliers pistons kind. Forged crank would be GREAT too, just for safety to be sure will support the extra power you want to add, but has been told cast cranks are able to support untill 500 HP  being a street/strip car ( not race ), but experts will chime out here better than me on that.

[RD]

read this for starters:

http://www.440source.com/blockinfo.htm