383 carb sizing question

[azazello]

Hi all,

I'm rebuilding a 383 (pre 1963 kind) and am investigating different carb/intake/cam/header combinations.

Right now I'm looking at a 750 Double Pumper on an Edelbrock Performer RPM manifold with 1 7/8" primaries and 3" collector with 3" all the way back.

I'm still undecided on the cam.

Besides the high volume oil system (wet sump), MSD ignition, fluidampr, and underdrive pulley setup everything is stock.

I'd love to run a 750cfm Dominator if for no other reason than it looks so slick, but I'm not sure if that's overkill. I know looks aren't the main thing, but man.......

My concerns are that for the application, a vacuum secondary carb might be better because its a relatively heavy car (4800lbs) with an automatic tranny and stock rear end. (However, these might change in the near future.) Not a daily driver by any means, but basically intended for street use with occasional trips to the track.

Thanks for any suggestions,

Pat

[Christopher]

I have run a similar combo like this for many years in a 70 Road Runner.I use the Mopar Performance "Street Hemi Grind" cam.Which is now the 280/480 cam.I use a 750 Holley Double Pumper and it works very well.I don't know what car weighs in at 4800lbs,but this is the cam I'd use.

[azazello]

Thanks for the info! Yes, that 4800lbs is not a misprint. The car is a 1960 DeSoto Adventurer -- I know, I know..... it may be a little old and missed the "Golden Era" of Mopar street muscle, but it's in tremendous shape with only 35k miles on it!

It's been pampered for 40 years (grandfather bought it new back in the day) however, I thought it could use a little spice. It ran great before I started work on it, and hopefully it will be even better when I'm finished.

Regards,
Pat

[Christopher]

Sounds like a cool car to me!!! Good luck with your DeSoto.

[Brian Mills]

I like it ! Wish I knew where to find one!

[Old hippie]

Sounds like one hellova cool ride!!!!! But....if you are going to move 4800# (!!!) with an early 383 you are going to have to build in as much bottom end as you can. That means trading off some top end power to do this. Here is the combo I would run. Edelbrock Performer RPM intake or the late model cast iron intake off of a 400. Even though this is an iron intake it is still a very good intake and would allow you to run a spread bore type carb.. The spread bore carbs feature small primarys and huge secondaries. Great for bottom end torque and fuel mileage. Get a set of late model heads ( 346,912,452 casting ). They are far and away better heads than your stockers and are cheaper than rebuilding the stock 512 ( I think) castings for unleaded fuel. Have 'em milled 20 thou to help offset the compression ratio drop. I would not run the Mopar 284/484 cam in this car. I would likely run the repo 440hp cam. It will build scads of bottom end power. I also question the 1 7/8 headers and the full 3" exhaust system in a car this heavy. The bigger you go with the primary tube dia. the more you take away from your bottom end. Same with the rest of the system. I would use 1 3/4 primary tube headers (3" collectors standard) and a good 2 1/2" exhaust system with a balance tube and 2 1/2" three chamber Flow Masters. That Dominator????? Great stuff for wowing the troops at the 'Burger barn but the wrong carb for this deal. If you can find a Thermoquad in rebuildable condition, go for it. If not, Holly has a t-quad replacement carb., 650cfm I think that should get the job done nicely. Good luck. The old hippie hisself.

[Brian Mills]

Old hippie, do you think you could lend a hand to a pair of pre-magnum throttle body injected pick ups? We have a thread going on the Jeep Truck board, and were about to go past tires, gearing and tuning, and talk cams porting and exhaust. I'll understand if small block and V6 is not your best field.

[DartGT66]

The best thing you can do to your 383 in such a heavy car is to replace it with a 440. However, since the tranny attachement is different it would not be a bolt on. Best thing to do with your 383 is to get decent heads for it. The older B/RB heads are a lot worse than the newer '68& up heads. You just have to mill them because of the bigger combustion chamber to retain your CR. Like said in the above posts, I would too concentrate on low end torque with a car that heavy. Otherwise you need very steep gears and a high rpm converter or the car will be a dog. I would not use the RPM intake, the performer or a late stock iron intake should work fine. I would not use a double pumper of any kind but a vacuum carb instead. The size is about right. Either Carter, Edelbrock or Holley 3310 should do the job. The 750 Dominator is a good carb, I have used it in a 3000 lbs 3.91 geared A-body with a 383, but your car is so heavy that it takes far more time to accelerate through the first gear than is good for a double pumper, a vacuum carb works better and can be modified for great performance. I prefer the Holley. If you seriously look at the big port RPM intake, then go ahead and take the RPM cam too, they are designed to work together.

[TD]

I have a 72 Chrysler Town and Country that weighs about 4500 pounds. I went from a stock 400 2bbl single exhaust to to a 4 bbl dual exhaust with dynomax mufflers. It made quite a difference in performance. I later changed the cam (Stock Roadrunner cam) and that really woke the care up when you put it in passing gear. It pulls away from a stop just as good as it did with the stock cam. I use this car for towing and these changes have made a world of difference in pulling power and the gas mileage is a little bit better.

By the way, the 383 and 440 use the same transmission.

[azazello]

Thanks everyone for all the info! I'm checking out Holley and Edelbrock's offerings on vac secondary carbs -- can anyone tell me why a vacuum secondary is better on a heavy car? Is there a specific reason or is it just a good rule of thumb?

[Christopher]

I still recommend the 280/480 cam.It's not that much hotter than the stock 440 cam.I've been using it for years,and I get 16 mpg in the Road Runner with 4.10's and a 750 double pumper.