Top Speed/Comfortable Cruising Speed

I find this post and its replies interesting. It reflects opinions on our cars' perceived capabilities at speed. It offers opinions on our own skill and comfort levels at speed. And it points to issues involved in sharing the road with other drivers. That said, all of these points are valid despite the age, condition, or any type of car we're driving.

I drive my 60+ year-old Chryslers because I like to drive my 60+ year-old Chryslers. (And my 60+ year old Dodge, too.) I am not shy about using the pedal on the right when conditions are right. But I keep in mind that the "safety features" of my cars are essentially an afterthought, if thought of all. So, I tend to keep the speed at or a few over the posted limit, hang out in the granny lane, and wave at the drivers blowing my doors off. My Chryslers are for cruising, and I make the time for that whether it's a six mile drive for ice cream or a couple hundred miles to a show.

If I'm in a hell-fire hurry to get somewhere, I drive one of my late model cars. Ninety miles an hour may be okay in my old cars, but I have other cars where ninety miles an hour is a safer choice.

I get it that we all have different cars with different capabilities. Heck, I drove my 1963 over 800 miles between 60-70 and (occasionally) 75+ on a long trip. So I'm no extremist on this issue. It's just that when I drive my old cars, I'm happier rolling along, enjoying the time I share with a car that few others will ever have. I figure, what's the hurry?

Thanks for reading this long post. And if you see "TAILFINS" on a tag of a 1960 Chrysler rolling in the granny lane, move to the left, give me a thumbs up, and pull away at your chosen speed!
I agree 100% I’ve got nothing to prove to anyone. These old cars aren’t a pimple on the *** of the new ones in terms of speed,safety, stability, and most of all braking power. Anyone who says different is blowing smoke up their own ***.
Something to add, I sell tires for a living.
The tires our cars came with, 14's and 15's are becoming harder and harder to get. Few manufacturers make a decent ply tire for a 5000 lb car. So knowing this you have to weigh your safety and side on caution. My 68 polara I waited 2 months to get a couple 215/75r14 Hankook white walls. Sure I could of went Coker but 1000 bucks for a set of 14's just wasn't happening. White side walls are dinosaurs. So keep in mind if your running them and get a chance buy them.
Even white letter in certain sizes is challenging. It's amazing a 3/4 ton truck today weighs about what our land yachts do and they run 10 ply. Interesting 40 plus years ago just bias tires and definitely not the technology in what today's tires are.
We never had any tire-wear issues on our '66 Newport or any other Chrysler product for that matter as I always kept the tire pressures at least 30frt/28rr. Looking at the "max load" rating of those now-small tires, at 32psi it was close to 2000lbs/tire. Even the current P225/70R-15s are over 1700 lbs/tire at 35psi. Never had any issues or concerns as long as the tires didn't suddenly vibrate!

Of course, at the used to be "industry standard for smooth ride and decent low-speed handling", 24psi, that weight-carrying rating would be considerably less. Chrysler also usually noted, in the owners manual, that "For speeds over 75mph, increase inflation pressure by 4psi" (over the base recommendation), which would mean 28psi. It was usually common knowledge, back then, that 30-32psi was needed for best high speed durability (and lessened heat build-up). Plus, of course, best fuel economy and the responsive steering response Chryslers were known for, back then.

Keeping the cold inflation pressures in the 30psi range meant, back then, that the car was "ready for anything which might come".

Just my experiences,
I've done just under 120 in the quarter mile in my Fury. It feels ok at that speed but I also wouldn't dare do any type of evasive maneuver or even move the wheel at all.

I've done 155 in a modern car and ~170 on a motorcycle. Both of those felt substantially safer than 120 in my Fury.
I think the fury would look much tougher going down the quarter than most of the computer cars of today. Also at the car shows! Ive had 3 newer challengers, 1 SRT that I took to 150, got rid of all of them, have fun with the old schools now days. All manufacturers from the 50's to 70's make up the best car show cars! My opinion!
215 km/h..........133,5 miles with a 383 4bbl 2.76 and 75 series tires....autobahn!!
70 miles is a nice cruising speed.
1st 1968 PK21 with 440 6bbl in 1970 as a 17 year old (no worry of old suspension, wink, wink) it ran like crap when I got it, previous owner drove it and said I had gotten it to run like a 318, I'm like wtf you sold me it in this shape, that's OK the motorcycle I traded as part payment was dodgy (he wanted it). I re-tune and he re-drove it and said "now you got it running like a 383". I eventually got it right and with 3.23 gears and new best Michelin radials at the time had no problem 'Pinning' the 120mph Fury certified speedometer out at like 3/4 on the pedal with 1/4 to go. I think the top speed was in the 160 mph range as things come up on you real fast at that speed on the Interstate and the old Road & Track adage "If you look out your side window and the scenery is a constant blur, your doing over 150mph" worked. I had put a new Stewart Warner electronic tach up in the lower A-Pillar and I asked my friend riding shotgun to look and see if I was pulling max 6.5k revs on the tach as I was very busy looking way down the road. He responded "Tach? I'm looking at your gas gage and you've used up a 1/4 of a tank already" lol. I had picked up a complete Cuda Rallye dash and wiring harness in a garage buy with the 150 mph speedometer & 6.5k redline tach and one Saturday took the dash apart on the Fury to see what it would take to put the 150 speedo in. I got as far as that I'd need another Fury gauge base and out of time as it was date night, never came back to it.

Some other notes about my 1968 PK21's (2), wind buffeting noise would disappear after 120 mph and all would be fairly quiet with Hemi mufflers. The second PK21 440HP Maryland State Police pursuit 4bbl (650 Holly) car when I first got it I thought the vacuum secondary's weren't working (around town) and started to fiddle around with springs, it wasn't until I did a flat out run on the Interstate that I realized due to cam or whatever, is that they would open up after 120mph and that is when the 440 would git'up & GO! well on the way to pin with room to spare. Previous owner of my 1st PK21 which originally had a 383HP in it said the 383 would pin out the speedometer pretty much flat on the floor but the 440 you could back off the gas pedal and it would be awhile before the speedo would come off pin.

I eventually around 1973/74(?) after putting the 440 6bbl in the 2nd PK21, I put the 440HP 4bbl Holly carb and manifold on the 6bbl motor for gas mileage as gas was going up around 45/59¢ a gallon and the six barrel with very lite toes would only get 12mpg, with heavy toes 4 to 6mpg, average around town was 9mpg with the 3.23 gears. The one time I threw the 3.91 chuck in... well you didn't even want to think about it... it was like my Caddy with the 490(?) and 3.9x gears it was just gas station to gas station LMAO.
On a 200 mile Interstate speed run to NYC to buy my 1st Harley with the 650 4bbl Holley I got 15mpg with a overall average speed of 95mph. We (I invited the owner of 1st PK21 along for the ride and he was impressed) had to keep it below 120 for quite awhile along the coast in the morning as there was quite heavy fog. Thank god that I had racing Raybestos metallic brakes all around for the jackass guy in the Beetle in the left hand lane doing stupid slow (and that he had his lights on) when I came up upon him @110 in fog.
I wanted to get 2.91 (6cyl) rears or I take it the 2.76 (to much) which was optional for the C-Bodies, not for the gas mileage but to see what top speed could really be... but that would've involved going to the boneyard, spotting & pulling the chuck as my 3.55 & 3.91 chucks were bought as a after thought when I went somewhere to get something else from the want AD's with a 'what else you want to get rid of'?

My 1977 PK41 with the lean burn 440 in the early 80's... I never really did a full flat out run to see what the top was, maybe the 140mph speedometer was intimidating, but by then I had my Harleys full tuned to do my high speed jollies and I crashed the PK41 into a ditch on a wet slick road in a corner with a heavy foot on the pedal (80+) tweaking the stub frame to the right. Plus I was getting older... sigh.

My 1976 Gran Fury Brougham with a 360 2bbl, (de-catted single exhaust) out on the Interstate, set the speed control @90 and press & go from there. It was pretty good on gas mileage even with the A/C on, best I did was 22mpg.

The 1968 Fury III 4dr sedan I had, with 318 2bbl with very high mileage, after I replaced the very worn timing chain (surprise, surprise, no nylon gear) and hacked dual exhaust installed would get the speedo well up past 120mph with 3.23 SG. Another laff.... when I first got the Fury III it had (the traditional) only 1 small dent in the lower right rear door into the wheelwell. When I got rid of the car (after it was rear ended in a 4 car, I was the only one too drive away) I pointed to it and said "I'm responsible for ever dent on this car" Well except the lower door one and the ones where I got rear ended. ROFLMAO.

My 1968 Fury Fastop... well lets just say I got a awful lot of speeding tickets in that car. I don't know what it was... 55mph days, unfortunate luck? The Fastop? Color? This was a replacement $100 car for when my Fury III got stolen for the 2nd time and they dumped it in a commuter rail lot going unnoticed for weeks, grrrr and I didn't have the Fastop for long as it was destroyed hitting a immovable object. Actually I parked the Fury III for awhile and robbed it for parts (transmission) for the Fastop.
I thought I was pretty class going from a 4dr sedan to the (no dents) sporty 2dr Fastop. heh...

:lol: :thumbsup:

(edit, added file picture, just spotted memories)


I didn't get the fender skirts with mine.

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They all "should" be a dream to drive at 75. The current 64 New Yorker 413 here with the low and rounded front sheet metal is a lot less subject to side wind and truck draft buffeting than the later slab side models.
Set your ride height "before" you do an alignment, very important. Or you will have bump steer induced instability with each rise and fall of the front end at speed.
And more than the minimum amount of positive caster will make it over responsive to wind and road crown.
I don't remember ever driving a C over 90. But I have been driving them regularly at 75 for 15 hours at a time since 1974.
I have owned no pre-63, but would like to, so can't comment on them.
The big mid 70s Chrysler Mopar's are as good at 75 as any other C body after1964. And better at emergency lane changes than any other year C body.
I'm asking this question because I want to know if the work I put into the front end suspension of my car has given my car at least a comparable level of feel and performance to other C bodies. I just want to know what the highest speed you've had your c body up to is and what speed you feel comfortable with cruising on the highway.

My top speed is 90 mph, this where the front end starts floating. I feel comfortable driving on the highway at 80 mph.
My New Yorker is the only c body I've ever ridden in (and I would like to change that at Volo if anyone is willing) so I currently have nothing to compare it to.
Thanks for the input in advance.
Just after I picked up my 64, I decided to drive it to work. Left work at 5 am, no traffic on the road, not paying attention to the dash, just enjoying the trafficless drive. I’m in Canada, the speed limit on the road i was on is 80 kph, i had a quick look at the dash and it was reading 80 …… MPH couldnt tell i was doing 30 mph over the speed limit
I was just on the northeast extension of the PA turnpike. 70MPH speed limit with 80MPH cruising speed between the concrete "Jersey" barriers. The convertible top raises about 3" off the center bows at that speed. Good times.
On my’68 Polara 383 2bbl, 75-80 seems to be its happy place. No problem getting up between 90 and 100. Above 100 it floats a lot more. In my case in particular above 85 Or with a head wind, the right side of my hood seems to flutter more than I like. Not sure if the skin has delaminated from the bottom structure, or I start getting some weird air flow through the engine compartment. In ND the interstate speed limit is 75mph. In SD it is 80.
28 inch tall tire 3.23 @ 5000 rpm = 129 mph 27" tire = 124 mph
28 inch tall tire 2.94 @5000 rpm = 141 mph 27" tire = 136 mph
It takes more than stock hp to push a barge to 5000 rpm in high gear and some real estate. It also requires proper tires and suspension, back in the day is not now....
I would not trust anyone's large barge car to handle speeds above 70 mph let alone stop on those asbestos linings
The 1970 standard 440 (E85) gave max torque at 2800. With JR78 tires, which were 28,9” tall, and 3.23 gears that translated to 74 mph. Which in my old man’s NYer seemed to be the sweet spot. More than that felt like pushing. Above 110 the hood began to tremble at its far corners, as the air came rushing in.
Wallace Racing has a bunch of calculators on their site, and others too. You need to know your tire size and also estimate converter slip. It’s usually a few percent.
I grew up on a dairy farm with 4 generations on it. I only new my great grandfather for a few years he died when I was around 12 years old. He lost his hand in a corn picker on the farm and had a hook on his right hand. My dad told me the story of how that happened and the story of the trip to the hospital in my grandpas 69 Imperial. Now my grandpa wasn't a speed freak but he had several Imperials over the years and always had the engines built up because he loved to travel the US pulling his holiday rambler trailer with the Imp's. Back in those days trucks were used to work on the farm, not pull campers.

In the fall of '71 my great grandpa was trying to clear a plug in the corn picker and his hand got caught and he was pulled in up to his shoulder. He was in the middle of a 100 acre corn field by himself but managed get on his knees against the picker head and pull back hard. When he did it pulled his hand off, not cut, pulled it off! He always carried a pistol and fired off two rounds to get some help. A hired man heard the shots and when he got to him he had used his belt as a tourniquet but lost lots of blood. He took him up to the farm house and my grandpa told my grandma to call the hospital and tell them what was happening and they were on the way. He put great grandpa in the back, my dad jumped in the back with him and grandpa was driving. My dad said he had never seen his dad drive that fast. It was a few miles to the 127 highway but when they got there gramps put it to the floor and pegged the speedo in about 1/2 mile but didn't let up. There is one long S-curve about half way to Jackson and dad said his dad let up just before they got to it. Dad said he was watching the speedo and the needle just started to come down from 120 when they finished the s-curve and gramps floored it again. When they got to the hospital they were not ready for them, the hospital staff said they had just gotten off the phone with my grandma and could not believe they had made the trip in less than 9 minutes. On the map below I pointed out the s-curve and it doesn't look like much but in my younger days in my 70 340 dart, late one night I hit that curve at just over 100 and it was scary. Now days I regularly take that curve at 80 in my 2021 Tundra and it doesn't feel like anything.

My 68 Sport Fury has its original 383 4bbl with the 727 and 2.76 rear end. It is all stock with a Pertronix electronic ignition on it and it runs at 70 no problem, but it seems to really like going 80 and even 90. I don't drive like that, but when my brother and I were driving the car across the country back in 2004 he had no problem putting his foot in it and we would run at 80 to 90 for hours across I-80 in Wyoming and Nevada when he was driving. I am much more conservative and kept it at the speed limit or just 5 over. In 2017 I stepped up from the original 14 inch Magnum 500s to 17 inch American Racing VN501s with modern BF Goodrich performance radials and it now rides and handles extremely well for a large and heavy car.