My 66 fury has a 383 with the horrible 2.92. I want the car to launch when I pedal him, and it does a bit with the torque, but I think I need a 3.54 or 3.73. So, what do you guys with this already done....think. I will not be driving this overland, only short hops and want some punk. What do you think on rear gear ratio please. I am being oppressed by a friend who had a 340 duster and thinks 4.11, and I am having indigestion. The 340 is a high rev dog, and the 383 is a low rpm torque monster, so am thinking that just a taste of more gear is enough. So.......
What rear gear???
- Thread starter 66furys
- Start date
In order to verify which axle ratio you have, there should be a metal tag on one of the pumpkin bolts with that stamped on it. I strongly suspect you now have a 2.76 if the car was originally a 2bbl or a 3.23 if it was a factory 4bbl. Those were the standard gears, but could be flip-flopped as an option.
Even with a 2.76, it should lay about 2-3 seconds of rubber rather than "wasteful" wheel spin going up in smoke, on dry pavement. Even with "a gear", it will NOT have the "launch" of a modern car with an 8-speed automatic and approx 4.7 low gear ratio. Tooo much weight to get moving from a dead stop. NOW, there are a few members in here with 500 cid stroker motors, but they also made many OTHER modifications to get the cars to their full potential with those motors.
My (somewhat biased) recommendation might be for a 3.55 rear axle ratio (to not completely kill any enjoyment should a road trip beckon) and a '68 Road Runner torque converter (aka 10.75" diameter) at stock stall speed. Be sure to upgrade the MOTOR MOUNTS, too!
My biases? I like to enjoy the firm torsion bar chassis calibrations on the highway. The natural cruising speed for our '66 Newport 383 2bbl is 75-90mph. It has the standard 2.76 gear and everything works well and more economically that way. With 90mph being right at 3000rpm. My '70 Monaco Brougham 383 "N" car is running about 75mph at the same speed (with its taller factory-size tires). My '80 Newport 360 2bbl and 2.45 rear gear, it just wants to "Eat Road", period. Which the factory HD suspension fully supports.
In the mean time . . . tell your A-body buddy that it's harder to make a stop light racer out of a 4000+ lb car than his "lightweight". That C-bodies can do that, but with many changes made to them, all of which cost money and need to be well-executed and finessed. The other thing is, how much does he actually drive (miles) his car with that low rear axle gear? C-bodies were meant for driving, especially on the highway, where you really experience how much better they were than other non-Chrysler Corp cars, whether it is the engine response for passing or highway fuel economy. Everybody has their own tolerance levels on these things. Do NOT be intimidated!
Regards,
CBODY67
Even with a 2.76, it should lay about 2-3 seconds of rubber rather than "wasteful" wheel spin going up in smoke, on dry pavement. Even with "a gear", it will NOT have the "launch" of a modern car with an 8-speed automatic and approx 4.7 low gear ratio. Tooo much weight to get moving from a dead stop. NOW, there are a few members in here with 500 cid stroker motors, but they also made many OTHER modifications to get the cars to their full potential with those motors.
My (somewhat biased) recommendation might be for a 3.55 rear axle ratio (to not completely kill any enjoyment should a road trip beckon) and a '68 Road Runner torque converter (aka 10.75" diameter) at stock stall speed. Be sure to upgrade the MOTOR MOUNTS, too!
My biases? I like to enjoy the firm torsion bar chassis calibrations on the highway. The natural cruising speed for our '66 Newport 383 2bbl is 75-90mph. It has the standard 2.76 gear and everything works well and more economically that way. With 90mph being right at 3000rpm. My '70 Monaco Brougham 383 "N" car is running about 75mph at the same speed (with its taller factory-size tires). My '80 Newport 360 2bbl and 2.45 rear gear, it just wants to "Eat Road", period. Which the factory HD suspension fully supports.
In the mean time . . . tell your A-body buddy that it's harder to make a stop light racer out of a 4000+ lb car than his "lightweight". That C-bodies can do that, but with many changes made to them, all of which cost money and need to be well-executed and finessed. The other thing is, how much does he actually drive (miles) his car with that low rear axle gear? C-bodies were meant for driving, especially on the highway, where you really experience how much better they were than other non-Chrysler Corp cars, whether it is the engine response for passing or highway fuel economy. Everybody has their own tolerance levels on these things. Do NOT be intimidated!
Regards,
CBODY67
57fury440
Well-Known Member
You didn't say which 383 you have. It is a two barrel or 4 barrel? Either way I would go with either a 3:23 or a 3:55. If it is a 2 barrel go with the 3:23.
My ‘68 Sport Fury with a 520” stroker, 3.73 rear gear and G70/15 bias ply tires, which are 27.5” in diameter is not a long distance highway car. At 65 mph she is at 3500 rpm, 2500 rpm at 50 mph. I think that you would be happy with a 3.23 rear gear but the diameter of the tire that you use is an influential factor.
You aren’t going to beat your friend with the Duster no matter what gear you put in.
You aren’t going to beat your friend with the Duster no matter what gear you put in.
Your gear options also depend on which case you have. I have the same basic setup and put 3.91's in mine recently with a helical gear sure grip and running 27" diameter tires. Love it and yes I can still drive on the freeway
yee hah....all great comments.....appreciate it. This engine is the four barrel in this sport model....but power is not great. So, just want a bit of sport with this setup. Would like to be able to spin the tires, but doubt it can do it with the 292.....but have not gotten to that point. This one came with the 741 el cheapo center section....but OK for this car. Just needs a bit of push to get going. Thanks
Well, with the 741 case your options are going to be much more limited but I think you can get 3.73 gears for that which would work well. In my opinion if putting money into the rear end for gears I would try to find a good 742 or 489 case to upgrade instead.
Setting up your timing curve will help off line performance, then after car is tuned I would not go over 3.23 for a driver.
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57fury440
Well-Known Member
The 741 case is not bad. It's not an "el cheapo" unit. With an automatic you would not have any problems. I've had all three cases and unless you are racing it will hold up just fine. The 489 I have in my 57 has 3:91 gears in it with a four speed and 27 inch tires. At 60 MPH I am about 2950 RPM. You should be able to spin the tires easily with 3:55 gears.
Right, it is just that over the development of the rear, it got better, stronger, bigger where necessary for power and torque. And you are right, for a low power auto, the 741 is fine. But, I will go to carlisle and look for a used one, and try to spend less than the 250 plus 500 to rebuild mine. And, I assume Boyd meant a 3.23.....and for the life of me I dont know why momma mopar put in a 2.92 in a sport fury with the four barrel 383.....hmmm.
Ripinator
Old Man with a Hat
Yes. The car should have been delivered with a 3.23, if it was originally a four-barrel car, but maybe it was ordered with the 2.92 or someone changed it over the years. Do you have the build sheet for the car? It will tell the tale.
This car is a good survivor, but, has been worked over from stem to stern over the years. The fuel tank was pulled recently, but I do not know if build sheets were on top of the tank or where......but no, no docs. The good thing about this one is that the superstructure is good, although some of the pans have holes and rust, it is not bad. The bad thing is that somehow, the previous shankers somehow ruined the steering gear, and worked over the electricals so badly that it caused several fires under the dash which I did not see before purchase. Interesting car for someone like me that drove them back in the day.....my first 53 bought in 1962, and spent my HS days drag racing several of them. Trying to relive my yoot, and laughing at myself the whole way. Latest short road trips have been good, and takes me back a bit.
Ripinator
Old Man with a Hat
Mighty fine. If you haven't looked behind the rear seatback yet, you may find the build sheet there. That is where it was on my '66 convertible.
fixed the 2
Someone had put on magnum 500 wheels that had a real bad interference with the hubs and would not come off. I finally ground the inside of the wheels to allow me to remove the old 14 inch wheels. But, I got new rally wheels in 15 inch. And, the used tire guy here had some 255 60 tires fof
Aaargh, hit the wrong button. So my rears are now 255 60 15 that are about 27 in diameter. I used 7 inch rear and 6 inch front wheels that seem to work....not much clearance on the skirts. Soooo for now, OK with this setup. I find that the rear leaf springs are winding up a bit and the rear snubber is hard on the body....so may need some attention to springs one day....poor old thing. Everything worn out.
3.23's would give you pep and still have highway legs. If you really never go over 55-60mph and you want the most gear, a 3.73 or 3.91 with a 27" tire would be ok cruising a back road. You'd be unhappy on the interstate. You'd have a lot more umph off the line.
383 doesn't have a long stroke, they can use a little rpm, thinking about it like that 340 isn't wrong.
383 doesn't have a long stroke, they can use a little rpm, thinking about it like that 340 isn't wrong.
The Chevy 302 and Chrysler 383 share very similar stroke-to-rod length ratios, near 1.9, which is better for high rpm capabilities (with, of course, good connecting rods, although the pistons in the 383 are quite a bit heavier). All the Chrysler needs is better cyl head ports.
CBODY67
CBODY67
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