You guys have really nice street combos! I have a healthy motor and I think this car would run easy 10's in street trim but I really don't plan on racing it at all and just want to make it more streetable.

MikesDuster, I want to stay with the 275/60/15, any taller on an A-body and it might start rubbing the rear quarters and may sit up too high, I think the 28's look perfect.

'71 Charger, 4:10's with 30-inch tall tires, 440, A727 TF Trans.

Yes, I can and do drive on the Freeway, but not often. It does tend to wear you out a bit.

I also have 4:10's in my '74 W200 Power Wagon pickup, with 33-inch tires, manual transmission, 360 engine, also Freeway Driven.

My '79 CJ5 Jeep, AMC 304 V8, manual Trans, 33-inch tires has 3:73 gears and is a very good compromise of acceleration performance and freeway driving.

What are your cam specs?

I had 2.76's behind my 493 with an MP509 cam and stock converter in a 4800 lb C-body.

With over 500 ft/lbs from 2000 it had no problem getting around town but it wasn't "happy" cruising where a 2.76 put it.

I put in a 2800 Turbo Action converter to cushion the 1100 RPM neutral drop on the drive line and a 3.23 SG and all is good now.

Kevin

Frankly the gears are not going to wear out the engine sooner then blowing it up at track so who cares! I run3.91-4.10s with 25 tall tires and have run 4.30s and 4.56s for close to four years and have driven them for hours at a time. If your cooling system is good and engine in tune a bit of 4000 will never hurt it I run LT tires with the 4.56s too much worry for nothing besides you won't get the tickets for speeding going 60-70mph on the interstate

Frankly the gears are not going to wear out the engine sooner then blowing it up at track so who cares! I run3.91-4.10s with 25 tall tires and have run 4.30s and 4.56s for close to four years and have driven them for hours at a time. If your cooling system is good and engine in tune a bit of 4000 will never hurt it I run LT tires with the 4.56s too much worry for nothing besides you won't get the tickets for speeding going 60-70mph on the interstate

I use 4.30's and run the 30 x 9 Hoosier radial slicks. I drive to the track on them and race on them. I turn about 3200 at 60 mph and dive it the 90 miles to Carlisle like that on Rt 83 and the PA Turnbike. I use a 9.5 Dynamic street/strip converter. It does not bother me at all on the highway as most cars ran 3.91's or more gear when I was a kid in the 60's as I remember riding in a friends brothers 69 Cuda 383 with 3.91's and short street tires about 25 or 26" tall. It seemed like he was turning 4000 rpm at 60 mph(just a guess as I was 14 when riding in it)and it seemed everyone with a hotrod or muscle car ran alot of gear and still ran the highway. So I guess thats why 3200 rpm at 60 dont bother me. In fact it sounds like the eng is just purring along at that rpm. Ron

I can see a gear swap from 3.55 to the 2's if you go on a lot of 2+ hour drives. Might want to try to go 2.5" exhaust after the mufflers to bumper to quiet it down. I have 3.55 with 275/60/15's on my sb demon I usually keep it at about 2,800rpm which is about 63mph, when I get above that speed the road and wind noise become more of a pain.

Paul, That would give me a headache lol, I'm not worried about my motor, it could handle a 250 shot of nitrous. I'm just worried about my annoyance level. I got real spoiled to my Mustang going 70 at 1900 rpm's.
I think tightening the converter some might be all it needs, if not I'll install some 3.23's.

Back calculate it.What's the max cruiser rpm you are comfortable with? What's your max cruise speed? What's your tire size or how many revolutions of the tire per mile?

With those three numbers you should be able to calculate it. Trick is that 60mph is one mile per minute. So revolutions for a tire to roll one mile become tire rpm at 60mph.

For example, 3000 rpm at 80 with 27" tall tire.

27 x pi /12 = 7.07 feet per revolution

5280 / 7.07 = 747 revolutions per mile

Turn ideal rpm at 80 into rpm at 60

(60 / 80) x 3000 = 2250 rpm at 60

calculate gear ratio 2250 / 747 = 3.01 That's optimum gear ratio assuming the car is either 4-speed or converter slips only a little bit. If converter slips 3% then multiply ideal gear ratio by 0.97, giving you 2.92 as the ideal ratio.
.
Now pick your closest factory gear ratio.

Done.

R.

I hated the 4.30s in the hot rod. They were fun for the first ten minutes. After that, they had to go.
I swapped them for a set of 3.23s at the Nats. Literally. I saw some guys looking at 4.30s in the swap meet. They had 3.23s in their car. I proposed a straight across swap with them doing the work.

I got up to speed on the highway, dropped the 833 into OD and smiled all the way home.

I miss the OD and plan on stuffing my 518 OD into the Imperial.

The highways around here are ~70mph almost constantly if you plan on getting anywhere, tollways push 80. Obviously you can go as slow as you want, but my biggest annoyance with 3.91s was the constant screaming of the engine just to maintain a reasonable speed...hence the double-overdrive 6spd that now resides in my garage.

If I kept it with a non-OD, I would have put 3.23s in it and putted along, I was done and over with running low gears on the street.

At 3,200rpm instead of 70, i'll be at 110! 70 at 2,000.

I'm running 4:86's with 275 50 15 tires..it's just a little wine..but fun..

I really have to reply to this as I am the member that bought the G/V from Frankenduster. Let me say right here that he is a stand up guy, fair and honest and I love his car. I have a 4,175lb convertible 66 Coronet with a 540" HEMI. 4.5" stroke, 246@ .050 I roller cam and 3.54 Dana. Torque is not a problem with this set up! Last fall, I drove the car almost 400 miles round trip to the Mid TN Mopar show in Lebanon TN from Chattanooga. Most of the trip was Interstate at 70+ MPH. 3,300 rpm with semi trucks on your bumper is NOT fun! The car had a 9.5" converter and would still "slip" 300 RPM going up a hill. With the G/V I installed a Hughes "2,800" 11" converter. Now 70 MPH is 2,500 RPM on the flat and level. It still gains 200-300 RPM on a hill. But it is SO much more pleasant to drive on a trip! In an hour drive, the noise, vibration etc. is VERY reduced. With the 640+ ft.lb. of torque, I should have sprung for the TCI "power adder" converter for $900 with a stall of 2,200 RPM but couldn't afford it at the time. The OD ratio ends up at 2.76 and the car is just a joy to drive @ 60-70 MPH. In short, if you have the torque, you just don't NEED deep gearing, I like my "rear end" just fine, don't you?

Yes I do, and she matches my car.

why not put a 518 in it?
I run 3:91 with a 440 in my cuda with 26" tall tire and 60 mph is about all I care to cruise the highway at. I'm thinking about a 518 swap over the winter.

Once you've driven modern muscle with a 5 or 6 speed you realize what your missing out on.

My '63 was built to do lots of street duty with 2800 stall and 3.55 gears and 275/60's. I had ran 3.23's in my '71 'Cuda but wanted to step it up a notch with the '63 build.

I'm going to throw a set of 2.76's that I have lying around just to see what it's like on the highway. If it does okay it might get the suregrip in that 3rd member!

With over 500 cubes I don't think they will be a problem...

"FrankenDuster I love that Charger! What RPM are you at when going 55 and 60?"

Thanks for the kind words!

My tach crapped out recently. It could be the fuse, I have just been too busy with work and another car project to tinker with it.
Its been a busy year. I changed the cam to the MP 528 Solid and switched from the 3.91s to the 3.55s. If I recall, I was at 2800-2900 at 65 mph. I have some 3.23s, but this 3.55 chunk has new gears and a rebuilt clutch type Power Lock diff. I don't commute with the car, so the gearing is a decent compromise for me.

I ran 4.56's in my tube chassis street Cuda with the biggest QTPro Hoosiers at the time. If I remember right it turned about 2700rpm at 55. Also ran 4.30's in my 62 Dart 330 with (I think) 28' Hoosiers. Those 2 cars where for wk end warrior street cruising though.

Edit: Now that I think about it, those 28's were more like 383man's 30's.

Now that I have my 70RR back on the road, 1st time since 1983. It's a Dana 3.54 4spd with 27" BFG's. Tach says about 2750 at 55. Calculator says it should be about 2400-2450. Car sounds like 2700-2800 to me, lol ...probably cause I'm getting used to these modern OD cars & trucks.

On the list for the A855 for longer Cruises/trips. Will make dew till I get the last few miner things fixed on this RR. Then I may do a Passon 4spd OD if he'll do a trade-in on the 5spd.

Hey...mickm I got her going!

It might be necessary to go to a bigger converter core to get the characteristics you want. I raced a 535 in a 3400 lb car with a stock 340 converter, which is 10 3/4 inch core. The stocker only lasted six passes but stalled to 3800 behind that motor with 906 heads. You should be able to get somewhere around 3000, to 3200 (maybe even 3400?)with a stock type configuration but modified guts to make it live. Then the 3.23 gears and tall tires won't make the converter slip too much. The bigger core simply has more leverage which helps reduce slip. I can relate to the rpm problem for long cruises. I even have a lockup trans, and 3.55 gears with 28.3 inch tall tires is still buzzing the motor more than I like. Funny, forty years ago it didn't seem so bad. Guys were running more gear on the street all the time, and driving freeways with them.

back "in the day", i ran 5.38's [ ] in my charger with m-50's on the street. 50 was just about all i cared to cruise at, but if somebody wanted to pass, that "fun gear" really woke up in a hurry !