3.23 to 3.55?

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domdart

domdart

FABO Gold Member
FABO Gold Member
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I have a 3.23 open 741 in my 4 speed 68 Dart. I am switching to a sure grip. I think I want to go with a 3.55 gear. Any members here make such a switch? I just drive around town except for the 2.5 hour drive to Carlisle every year. Are you happy with the 3.55 gear? Thanks FABO.
 
To me, the 3.55 gear ratio is perfect for most driving conditions with 15" tires.

With 14" tires, a 3.23 suits all overall roads the best.

If racing, different story.......
 
2.5 hr drive to Carlisle, I would leave the 3.23 in there.
I have 3.55 in my old truck, and I avoid the interstate, 28" tires.
 
I had a 4speed with 3:91 and loved the gear, great around town, high way a little steep but real fun gear so I would definitely go steeper, 3:55 aren't much different
 
I have 3.55's in my 383/Auto Charger. Love them. My drive to Carlisle is a little shorter, about 1hr 45 min. They're a little buzzy if you want to keep up w interstate traffic - 70 mph. Fine at 55-65.
 
tell us more about the rpm range of the engine, cubic inches, cam , etc. I drove to epping more than once with a 4 speed and 5.13s and a spool and 28" tires and a 340 . about 100 miles, 3600 rpm @ 60 mph. run low 12s at 113
 
Personal preference I guess. I prefer the 3.23 I’ver the 3.55. Hell I love the 2.94’s in the dart now. :)
 
I have 3.73 in my duster with a 275/60/15 , we run 2600 rpm at 60 mph. I went from a 3.08 to a 3.55 in my vette with a 255/60/15 gained 500 rpm, no big deal. The trade off was the car just plain drives better with more gear, accelerates nice and is not doggy at all.
 
Demonic said:
I have 3.55's in my 383/Auto Charger. Love them. My drive to Carlisle is a little shorter, about 1hr 45 min. They're a little buzzy if you want to keep up w interstate traffic - 70 mph. Fine at 55-65.
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^^^ This. I made the same switch in my Dart with 255/60/15's The car preforms better with the 3.55's but on a highway drive of an hour or more its a little much for me, keeping up with traffic. I usually end up running at 60 mph. Your results might be better than mine though, you being 4 speed vs my auto with 3800 converter. On a once a year drive I would probably just keep my speed down and enjoy the drive. This is my opinion, you might not mind running 70 or so.
 
I made this exact switch on my ‘79 Magnum.
Glad I did. I wouldn’t go back. It is just a few hundred rpm more than a 3.23 on the Hwy. at worst.

Performance wise it felt like a good tune up from a neglected engine. On the road, it was a nicer take off and it worked better getting on the Hwy. and going around cars for passing. The sweet spot for the 400B/727 B body with 245/60/15’s was in the 55-65 mph area.

Traveling at faster speeds (70+) required a slight tip in of the TQ secondary side making it thirsty. I’ve only had the car to 110 mph. Non sustained. It was a few mph lower than the 3.23’s but unless you need to be there.... I don’t think I’d worry about it LOL!

The drive feel was nicer. It helped give the car the missing “Pep” I thought it lacked. While it is not a huge gain by any means, it is noticeable and IMO, a delightful enhancement.

The only thing to make this better (and this is totally driver and engine combo dependent) would be an overdrive transmission for a serious rpm drop when in overdrive. Of course the engine build comes into play starting with the cam duration size not being to large as to become inefficient coupled with the torque converter operating in a too low of a rpm range and letting it heat up to much.

Being you run a manual gear box..... never mind.... LOL
But that’s added in for the auto transmission guys.
Figured they might like to know FWIW.

Also, FWIW, I drive off the far eastern end of Long Island to Carlisle Pennsylvania for the meet and I have ZERO issues with Hwy. traveling. It takes me near double your time to get there unless I hit traffic through N.Y.C. just right. Not a fan of 2 hours in traffic to travel a few miles.
 
The tires are 255/60/15's (27.1"). I put a 72 340 in it. It is modified to 10.5 to 1 compression, 2.02 valves, air gap, headers, 650 carb, probably around 400 hp. It is a dog out of the hole, but is scary fast once the rpm's are up.
 
domdart said:
The tires are 255/60/15's (27.1"). I put a 72 340 in it. It is modified to 10.5 to 1 compression, 2.02 valves, air gap, headers, 650 carb, probably around 400 hp.
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**** let it rev, you obviously didnt build it with MPG in mind. lol
 
Swapped the 3.23 for 3.55 in the landyacht several years ago. Made a noticeable seat of the pants improvement in take offs. Stock 318 bottom end, 340 6pack cam/heads/intake, 225/70/15s 69 Fury ragtop. I'm also 2.5 hours from Carlisle. If I keep my foot out of it, I can make it there and back and almost there again on one tank. Also have no problem running 70 mph on the interstate. Do it. You'll be glad you did.
 
With those tires I'd go 3.55's no hesitation, especially w/a 4-gear, if those RPM's bug You...... get another hobby! :D
 
I went from a one wheel 2.76 to a 3.23 Sure grip then immediately went from 14" to 2:55x15's. Dang I wish I had found a 3.55.
 
domdart said:
The tires are 255/60/15's (27.1"). I put a 72 340 in it. It is modified to 10.5 to 1 compression, 2.02 valves, air gap, headers, 650 carb, probably around 400 hp. It is a dog out of the hole, but is scary fast once the rpm's are up.
Click to expand...

With 27” tires I would opt for 3.73 gears if you are buying a new set of gears, 26” tires & the 3.55 would be fine.
 
I used to drive 2 hours to Don Garlits in Ocala every year with 3.55 and auto.

Not too bad.

My friend with 3.91's always bitched.
 
Me? I don't like getting passed by every Prius or econobox on the road. Here in Nebraska, if you don't run 80 you get your *** run over. But then I drive my stuff on the Interstate every chance I get. I'm putting 2.76's in all my automatic cars. I give up performance to be able to keep up with traffic. Just my thoughts! My 71 Polara in my avatar is an original NE Highway patrol car, had 3'23's, put 2.76's in with 235-70-15 tires. I could run 90 all day if I could get away with it.
 
I have a five speed manual in my 410LA with 3.91 gears and 28inch tyres. At 110kph (70mph) it revs at 2600rpm. Many friends in my club have low gears with high stall converters in there autos and are well over 3500rpm at hyway speeds. This is why I like my manuals.
 
well if you had a normal 4 speed in your car it would be revving too.. 5 speed is a game changer. be the same if one of those guys went with an automatic with OD. really nothing to do with manual and or auto. add an od gear to either and get results.
 
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