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Missed the part about 3.08. Depends on how you want to drive at highway speeds however a big block can lower gears (higher numerically) due to the insane torque made at low rpms
I would leave the 3.08s in it. You have more than enough torque and h.p. Unless you are planning on dragging the car and don't plan on much freeway driving. If that is the case them I would go the other direction with 4.11s
I am going to change from 3.70s to 3.08s in my 57 when I get the 383 stroker in it.
With the new head and cam technology, these things make power at low rpm. I have a spare rear end with 4:11's but probably wouldn't put them in unless I did a 5 speed. I just want to keep the car really close to original just with more power.
i would have done a bigger motor to twist a big gear, but I don't think the Munci, frame, rear end could handle it.
3.36 gears with a 700R4 overdrive. 1,980 RPM at 65 miles per hour in my 1962 with a 383 that dyno'd at 465 ft lbs of torque. I drove it from Orange to the Pomona Swap Meet and back last weekend and the gas gauge hardly moved. Hellacious low gear lets it smoke the tires at will. After installing this transmission I'm done with 1:1 high gear transmissions. In your situation with that much torque, and the fact that you already have the gears in it, If you plan on driving it on the street I'd try it first before spending the money or wasting the time to have the gears changed. I think you'll like it as is.
What gears have have you guys enjoyed with big torque? She has 308's
More information would help... what transmission and gear ratios? What's your mix of city/highway driving? Is your driving environment in a hilly or relatively flat area?
How important is initial off the line acceleration to you versus low rev highway cruising?
Have you tried the gearing analysis tool that I posted earlier this week in a new thread I started?
It doesn't make any difference how much peak power (or torque) an engine has. The most important issue in getting it moving from a dead stop is idle/off-idle behavior. If it has a high overlap cam that yields a low idle vacuum at 900 or so, it will be harder i.e. more revs and clutch slipping to get it moving than a base OE engine with the same gearing.
some engine specs and details would really help out if you posted them up
a 550hp 396 or 496 will behave differently;driving habits will dictate if you can keep reg tires or if a drag radial is safer noone wants a suprise at 60mph...broke my M/T loose once on the hwy didnt expect it; reality check!!
Without knowing Id leave the rear gear see how it drives otherwise youre guessing; get that "original" stuff out of your head the car doesnt know what gear is in it
Sounds like, if youre ready to go OD you already know to leave it be for now
when the speed limit used to be 55mph different story
Why even have 500-600hp if you aren't maximizing it's potential!
A 3.08 just isn't a practical rear for higher horsepower! Ya ya ya ya the torque, so you will be able to cook off the rear tires at will with that axle ratio!
If you are sticking with a Muncie of any gear spread, I would re-gear the axle to a 3.55 at least if you are still expecting to commute down the freeway reasonably!
If you insist on keeping what you plan, and you are going to rebuild the Muncie, then at least go for the steeper 1st gear 2.54, which would be the wider ratio boxes!
I would get it running and driving in its current configuration, and go drive that engine to see what you truly have in the way of a power band especially in the lower rpm ranges before laying out more money on theoretical as many people here are throwing at you! It is best to tune your gearing to the actual power band and operation range of your engine!
Every 500-600 hp engine I see mostly operates best with a tighter close gear ratio, but the 1st gear usually becomes a dog! And you want to not be so spread out on your 1st to 2nd gear throw! A 3.36 and 3.55 effectively tightens up the wide spread and makes for more drivability in your power band! With higher axle ratios 3.08 to like 2.xx ranges, You have certain back pressures and things that have been talked about! 3.08 was thought to be the edge of what is still real world! On this back pressure thing, me not having that problem running 5 and 6 speeds, never have really tried to grasp what all of that is all about, so maybe another enthusiast more educated in that can chime in and talk to that stuff!
Last edited by TCracingCA; 04-27-2017 at 03:17 PM.
I'm still not clear as to what transmission you have or what transmission you plan to buy? That will largely govern what rear ratio to use. Or, as SWDuke commented - how you think the car will be used?
Your thread title says Muncie but it doesn't state if it's a WR or CR Muncie. Later you mention possibly using a 5-speed. If you have a Muncie and one that's compatible with that 3.08 rear I will assume it's a WR gearbox. If you are doing a lot of stop and go city driving, that 3.08 is probably not going to be a lot of fun. If a lot of highway driving is anticipated it will be fine. If you by chance have a CR Muncie with that 3.08, your clutch will definitely not like stop and go traffic.
If you are planning for a new gearbox, there are all sorts of possibilities.
Last edited by DansYellow66; 04-27-2017 at 06:52 PM.
04-26-2017, 11:39 PM
What Gears? 500-600 hp big block w/Muncie
