cruising power/rpm range for 383?

[OzCuda]

Having another look at gearing on the Barracuda (3.55 diff gives me 3000+ rpm when cruising at 65-70 mph)  and wanted to know if there was an optimum power range for a 383.  I'm guessing it makes power across the range of rpm but wanted to know what was optimum to give me something to aim for (e.g. my 4.0/6 Wrangler was happiest in the 2200-2400 rpm range).

[hemiken]

Hi Mark do you know what profile your camshaft is please buddy.  Have you got access to your cam card by any chance ? will be easier to diagnose this way.

[Chryco Psycho]

To a point the cam will dictate the powerband but you also have to keep in mind the 383 has a short stroke  almost as short as the 318 so you will need some RPM to make it work as they are not torque monsters like the 440 

[dodge freak 2]

I'm running 3.91's with a 318 motor and 360 MP heads. Went from a 29 inch tall tire to a 26 inch...(was on sale, great buy with Goodyear rebate). Was worry about the rpms...now I have 2 mufflers (edelbrocks) on each side to keep the noise down and yeah, its 3000+ rpms going 60 mph..but if it wasn't for the tach I would have guess it was 2500.

Car runs great...pulls even better now in 3rd gear--every gear. I glanced at the tach after flooring it  for just a short ways...6000 rpms...do run a rev limiter, cause the rpms can climb faster than you might think. I need to change my speedo gear in the trans now, reads 5 mph fast.

On paper 3.55, maybe 3.21 looks great but out on the road I wish it had 4.10's now. (cheap gas is great thou).

[OzCuda]

Cam is a Comp Cams XE256H - what data do you need?  Intake duration - 256 (212 @ .050" lift), exhaust duration - 268 (218 @ .050"), Intake valve lift 0.447, exhaust valve lift 0.455, Intake lobe lift 0.299, exhaust lobe lift 0.304, valve timing 0.006, lobe centre angle 110, Intake centreline 106.  Descibed as strong torque through low end and mid-range.
Engine noticeably screams above 3000 rpm which is fine for play but a little tedious in the cruise.  I'm actually looking at going 255/70/15s on the rear (29" Vs the 26.5" I have now)  which should give me a reduction in Rpm of approx 10% or same as changing to 3.23s.  2700 rpm might be Ok but was wondering whether there was an ideal for this engine and stroke as Chryco indicated?

[dodge freak 2]

That cam is small, it run good and strong down low. 3.55 with a 29 inch tire would be a nice all around gear. At 45-55 mph it be perfect. At 70-75 mph the motor would be buzzing, not harmful but the exhaust noise could get to you if its a bit loud like many cars. If the motor has good valve springs the top speed would still be over 100...Many cars came straight from the factory back then with a 3.55 gear and only a 27 inch tire..and speed limits were 70 mph back then too.

The cam decides what gear would work well more than the motor. You could run a 3.23 gear with that small cam but in slower speeds stop light to stop light, the 3.55 gear would let the motor do less work to take off quick. At 45 mph the motor would be happier with the 3.55 gear, IMO...55 mph could be either way...over 65 mph, the 3.23 gear would start to shine and love 75 mph

[willard]

I have a stock 383 with 3.23, 1800 stall converter and 25,6" tyres (245/60R14). Dont know what is the cam but I have a voodoo waiting dor a swap. Recently I installed TF1 kit an did a test cruise today - still not loosing grip when i floor it. I assume the previosus owner preferred a setup (low stall) that is stronger at higher speeds - so that the wheels don't lose control at the start but then they launch pretty well.
With such converter the tranny doesnt overheat and i'm always crusing at above stall speed... the cons are rather lazy launch and no chirping tyres.

[dodge freak 2]

Another thing is the type of carb you will run. A vacuum secondary would work well with any gear. A double pumper-mechanical secondaries likes 3.91-4.10 gears.

What are you aiming for? A nice all around car that isn't very quick but nice to drive for long drives..at higher speeds and in the rain if necessary or a butt kicking hot rod that laughs at most cars on the road but can be expensive in gas and wear and tear on long  drives.

You can run a 3.91 gear car at high speeds for a long time but you need to push the pedal down and watch the gas gauge go down since you are getting 9-10 mpg at 75-80 mph.

A higher gear helps slow a car down thou when you let up on the gas. Which is how the factory got away with drum brakes in front.

I really think with a 29 inch tall tire 3.55 would be better than 3.23 unless you plan on going for over 200 mile long trips on the freeway. You could get two sets of back tires. A 25 1/2 inch tire for fun on weekends and those 29 inch tires for everyday driving. 3.55 is a nice gear, by switching tire height you can amost have it both ways.