Stock 383 - need some more ballhs

[wantone]

Hello!
  I'm looking to add some oomph w/o breaking the bank.   What do  you suppose is the best move on my part to gain some ponies?   

ORR should I just save up and get an EFI system?   If so - which one?

[1 Wild R/T]

What do you know about the engine's current set-up?

383's are tough to make run hard these days, Piston choices are very limited & assuming your has already been gone through it probably has a true C/R of less than 9-1 if it's got 906's on it probably closer to 8-1....  Even if it has 9-1 C/R cam selection is critical & if it's lower it becomes more of an issue....   EFI won't make any more power. it'll just optimize what you have...

If you have 906's either dig up some 516's or better yet 915's...   Get them milled .040-.050 to get the chamber volume down to 75-78cc... That'll get your compression up around 9.0-9.5 & you'll see a snappier throttle response, more torque & horsepower from off idle to redline

[wantone]

Good stuff right there^...   I was thinking that I am such a poor tuner than I'd best rely on the computer hahah.

[72bluNblu]

EFI isn't going to make much more horsepower. Maybe a little, but you won't overcome the low compression and stock cam.

As for making more HP, just depends on what you want and how much you have to spend. You didn't say how you engine is currently set up at all, so I'll assume it's stock with a 2 barrel, since that's how most of the 383's came. If the engine is in good shape, you can make bit more power with just a better 4 barrel intake like the Eddy RPM or DP4B if you can find one, a decent 4 barrel carb and a set of headers. Even with no other changes that could buy you 20-30 hp.

If you want more than that you'll have to address the compression ratio. Again, if the engine is in good shape and you don't want to do a full rebuild the way to do that is with a set of closed chamber heads, 516's or 915's if we're talking stock heads. With the compression ratio up you'll make more power, but you'll also be able to support a bigger cam too. Just depends on how much you want to spend.

[jimynick]

 "Get them milled .040-.050 to get the chamber volume down to 75-78cc. don't forget to give the machinist the intake while you're there so he can cut it to match the heads or you may have sealing issues. Just my 

[1 Wild R/T]

"Get them milled .040-.050 to get the chamber volume down to 75-78cc. don't forget to give the machinist the intake while you're there so he can cut it to match the heads or you may have sealing issues. Just my 

Never cut a Mopar intake.... You cut the intake surface of the heads.... That way the heads can be swapped from a 383 to a 440, really any Big Block... And the intake can be swapped without issue.....  Next realize the original head gasket was an .018 steel shim & a replacement composition head gasket is gonna come in around .039.... So really the heads are only gonna be .020-.030 lower than stock....   So the intake surface of the head gets cut .0123 for every .010 below stock.....

[Chryco Psycho]

Or grab a 383 or 400 block drop in a stroker kit & do 438 or 451 CI & swap that under you heads & intake with a good cam, you could cut down a 440 crank & use the 440 6.7" rods & just order new piston & have the assy balanced , there should eb a lot of 440 cranks & rods around with all the 440/ 512 strokers being built & even if the mains are damaged on the 440 crank it will need to be cut down below the damage to fit the B block  , it will still be cheaper than EFI

[rUNCHARGER]

383's aren't that bad in stock Magnum form. I would make sure the timing curve and carb are optimized and the timing chain and cranking pressure are up to snuff before giving up on it.

Sheldon

[wantone]

Cool - I have a 383 - orange and not blue so it's got to be the magnum version.   Running a manual choke (switching to electronic) 750 eddie.   haven't touched timing or tested cylinder pressures yet.   Currently has a vaccum leak and i'll be sorting that as soon as I take the carb off.  Otherwise this is a martian.

Will advise if I still hate the thing after that.

[moper]

It sounds like you don;t know too much about the engine you have. The first step in fixing anything is to find out what's been done. If it was rebuilt, chances are it's a compression ratio that will run well on cheap gas because builing in compression to a 383 takes a custom piston and some careful machining. If you want more power, the best way is to make sure what you have is maximized, and then possibly ad some bolt ons to gain some power. I'd suggest you take some compression readings with the engine warmed up and all the plugs out. Buy a factory service manual and start with verifying the basic setup of timing and carb. 

[Racer57]

At what point in cam selection does the brakes go to hell ?

[jimynick]

At what point in cam selection does the brakes go to hell ?

usually about when the guy goes to the bottom of the selection page! The driveability usually goes hand in glove with them. 

[72bluNblu]

At what point in cam selection does the brakes go to hell ?

Never. Just get manual brakes. The power brakes on these cars are awful anyway.

But if the OP has a stock compression ratio 383 he won't be able to run much cam before he kills his cylinder pressure anyway.

[73restomod]

Hmm.... On a budget 383 I would start with

Eddy RPM, 440 source heads, 1 3/4 headers, 2.5" exhaust at a minimum, and a cam with 265-275 intake 275-280 exhaust duration and around .5-.525 lift. Should make good power if bottom end is stout, and you could leave the heads off the board initial to save funds. If your gonna stroke it, than good heads become mandatory.

[wantone]

Hmm.... On a budget 383 I would start with

Eddy RPM, 440 source heads, 1 3/4 headers, 2.5" exhaust at a minimum, and a cam with 265-275 intake 275-280 exhaust duration and around .5-.525 lift. Should make good power if bottom end is stout, and you could leave the heads off the board initial to save funds. If your gonna stroke it, than good heads become mandatory.

I'm thinking there is a solid thread you could write-up with a few links to where you'd get this stuff.