For upgrades to your otherwise stock 400, either of those would be fine. The "783" cam is the original "HP" cam that was used in essentially all the Super Commando, Magnum, and Roadrunner engines, so you know it works and will idle well. The other one will have more of a "cam" sound to it, but I can't say if it would be any easier to live with. The narrower centerline or lobe separation angle will give it a little more "chop" and perhaps a bit more midrange-top end than the 783, as you can see in the basic RPM range. It's a tough choice, but I might just go with #677 if I had to choose between those two. How much of a price break are you getting? The Summit Racing brand cams are great deals, and lots of folks on Moparts have used them. I used one in my 360, and was very satisfied with the results.
Well both cams are priced the same according to the mopar performance web page they are priced at 171.00 but i can get one for 168.00 and that includes tax so i figure that once you add shipping into the figure from the web im guessing it would be at least a 10 dollar break and since i'm on an extremely tight budget the smallest savings is good !cowboy
Joined: Mon Jan 16 2006, 02:52AM
Location: Vantaa,Finland
Posts: 379
I have used the 272/272 .454" cam in a low CR 383, and it worked well. With a single plane, it pulled strong to about 5000 rpm. Although, the "summit" cams work too, I wouldn't bother with them. They are low priced, but the design is not very modern, and you get way better performance with some other grinds. Your car is heavy, and the engine has got very low CR, so I would even study some other choices with less .050" degrees.
This thing was the torquiest cam I've used...really is, imho, too small for a rb...even a stock one. But man if you want to pull a house around or smoke the tires forever, thats what you need. Great on gas mileage too I'm ashamed to admit hehe...
Joined: Sun Feb 26 2006, 08:46PM
Location: Kingston,Ontario
Posts: 5622
I have the cam that is in between those two.#P4286675 260/260 duration,34* overlap 113 centerline .430/.430 lift. Basically an RV cam that produces good bottom end--and that is what you need to get a heavy car moving. It is in my '68 New Yorker's 440 with massaged 452 heads,factory original pistons,valvetrain and intake,Carter 750CFM carb with the TTi dual exhaust system.Pertronix conversion in factory re-curved distributor. I chose this cam for reliability, GOBS of torque,and mainly due to all the options that require lots of vacuum. I really am satisfied with my cam choice.Works well in a 4600 lb car that can boil the hides at will,and still have a smooth idle, and cruise nicely down the highway.(I luuuvvv the sound of those pipes!)
I am not afraid to drive my car hard.At the top end the car still pulls hard and does not break up.Sometimes the only problem I have is not enough road or Mr. policeman! LOL! !stop Oh,yes I do get an average of 16-18 hwy MPG with it too! <span class='smallblacktext'>[ Edited Wed Dec 13 2006, 04:31PM ]</span>
Joined: Sun Oct 22 2006, 09:26PM
Location: San Antonio
Posts: 74
Corey in your application I would use the 783 (Mom's original "HP" cam), lots of low end torque and its a proven performer, ask any 440 roadrunner or GTX owner.