Well if you've been reading, I'm still trying to figure out if I'm going to swap in a 700r4. I'm overseas, haven't even driven the car yet so I don't know the power range of the engine.

I'm moving from CA to Florida and will most likely driving the car cross country while towing a small trailer.
Allright...please note if you're towing in CA, the max mph is 55. I will be taking a southern route to FL so if anyone knows if other states are the same please let me know.

So I used an online calculator and figured out with the OD of a 700r4, I will be turning 1700 rpm at 55mph. Of course I usually drive a little over but not that much. Oh this is a stock build motor.
QUESTION: Is 1700 too low of a cruising rpm for this motor on the freeway. I mean thats pretty low but it is a pretty healthy motor (also a pretty fresh build). Of course I guess I could cruise in 3rd.

Anyone have any input?..thanks in advance.

 

Your car makes 345 hp at 4800 rpm with 440 ft lbs of torque. Should run fine at 1700 rpm with the overdrive tranny. You should put a tranny cooler on it if you plan on towing a trailer no matter what tranny you end up with. If you go with the overdrive you will want to downshift on steep grades saves wear and tear on the tranny.

 

To whoever may find this in a search, I'm ending up in Afghanistan as a contractor for a year and won't be back till Mid 2010. I'll do the swap then. And to boot, I won't be moving to Florida, thus won't be towing.

 

Be safe and keep an eye out for the Toweliban.

 

First of all stay safe and come back in the same configuration you left in.

Now to the RPM and tranny swap issue.

Perspectives:
In the 1960s the typical speed limit in this country was 60 mph and drive trains were engineered to provide the best fuel economy for a given engine in a given car with the speed limit fact in mind. A typical engine of that era in a passenger car regardless of make or transmission at 60 mph will be running at roughly 1700 rpm, give or take a 100 rpm unless the rear axle is geared for towing or is otherwise extremely low. Virtually all cars came with a full fuel tank capacity capable of making 250-300 miles before being empty based upon the drive train setup. Pushing any car of that era to 70 mph is going to result in the opening of all four barrels of the carburetor and though maybe only turning 2000 or so rpm at that speed the fuel economy is going to be going to heck in a hand basket.

Considerations to Mods:
While there are kits around to adapt an overdrive transmission to a 394 there are other issues you may want to seriously look at before attempting such a swap. Not the least of which is the likely need for modification of the transmission tunnel, inclusive of toe boards and front floor pans. You might well achieve the same fuel economy results from simply changing the ring and pinion gears to something more fuel economy friendly. Ring and pinion gears are a lot less costly than a tranny swap. The 394 is a torque monster of an engine and can easily handle a higher ratio axle gear set without serious acceleration losses from a traffic light.

High compression and Ultra High Compression 394s might well be described as being as nearly as perfectly designed engine as has ever been produced for a passenger car and though in the day gobs of speed/racing parts were produced for it, it is simply best just to leave it alone beyond maybe sticking a Pertronix Ignitor II or III electronic module in the distributor.

 

Well to begin on rpm/speed/mileage, etc. I pulled up an online calculator and plugged in some numbers. Final drive with a 3.23, my 215/70/15 tires and the slim jim came to about 2700 rpm ish. With the .7 overdrive it's about 1800 rpm. Ok so better mileage, less wear on the motor, and reduced engine noise on the freeway. Sounds good to me. Don't get me wrong, I like the sound of a V8 anytime, but since I plan on driving to shows, the lower freeway noise will be nice.

As for the trans swap, I would be going with the modified bellhouseing, not the bolt in kit. This will still fit in the stock tunnel though tight. I have pictures to prove it. I may have to make a new trans crossmember but thats ok.

And lets consider this, if the Roto-hydramatic was such a good trans, why did it have such a short run? The 700r4/4l60E has/was in production for many years and installed in many many more cars. If it make the car that much more enjoyable to drive and I have the money....why not? Why all the work and expense? Because I'm a tinkerer. I like the challenge and the rewards.

 

Go for it! I put a 700 in my 64 F-85 and a 455. I like the car alot better now then before with the 330 and 2 speed. I went through 3 th350s before i went to a built 700. Man its a huge difference with cruising. Plus more gear for 1st. Cant beat it, best of both worlds.

 

BTW i had a 64 Super with 394 and slim jim. That trans sucks. 1st to 2nd is all goofy with a big lag between shifts. If i had the extra money i would do it in that car. But in my opinion i would beef up the 700. They wernt built for Big Blocks.

 

That way is one or the other, you lower cruising rpm and you loose gear from the start. With the 700 you get more on both ends. In my eyes thats a win win

 

I can attest to this. World of difference in rpms on the expressway just down a few gears on the ring and pinion.

With 25" tall tires and a 3.08, my car will be turning about 2700-2800 at 65mph.
You have to take into account how the torque converter feels about it too.

 

Backing up a bit in transmission history, the Roto Hydra-Matic like all GM transmissions of the era were sloppy shifters for those thinking the feel of a "positive" shift is absent. GM, as well as Ford and Chrysler, were wanting to market a car with an automatic transmission that lacked the feel of shifting gears with a standard transmission. All sorts of wierd things were done in attempts to make transmissions smoother shifting including using various additives in the transmission fluids. The pennacle of these attempts was found in Buick's Dyna-Flow, commonly referred to in the times as Dyna-Flush or Dyna-Slush.

The Roto Hydra-Matic, like all other GM Hydra-matics of the times also suffered from a really stupid gear selection setup with Reverse being on the opposite end of the spectrum from "Park" leading to a lot of unexpected backups when a driver intended to be in a forward gear or often the other way around. More than one garage wall suffered a hit from the stupid shift selection scheme and a driver not paying close attention to which gear had been actually selected, i.e.; Low or Reverse.

In the case of console mounted shifters found on Starfires and Pontiac Grand Prix's the reverse lock out button was atop the shift **** leading to drivers often accidentially depressing it and finding themselves in reverse instead of low or some other forward gear. The Roto is a great transmission when manually put throught the gears after running the rpms up. Almost as responsive as a standard transmission once the internal pressures have built up sufficiently to give that positive shift feeling.

Bottom line, the gear selection issues are what killed the Roto Hydra-matic and all other similar Hydra-Matics, not their shift characteristics.

 

I can see myself putting it in drive thinking I'm in reverse. That right there putting in a 700r4 could pay for itself.

 

Hee, hee! What a great and right on target rant.

Those of us who drove '50s, '60s, and '70s cars daily and across the country on vacations know those cars got us there and back. Usually without significant event.

Returned to being mechanically sound to original factory specs and spiffed up with new paint and upholstery those cars are just as serviceable today as they were then. Fuel efficient as a tin can on wheels? Hell no, but then neither are the SUVs and pickups so many choose to drive today. It's really quite foolish to think a 12 or less mpg car can be made economical enough to practically use in daily commute from the suburbs to work.

 

Nothing much to add to this thread, except outside of CA you will be able to run about 70 all accost the country, so will want to take that into consideration. Keep in mind that the speed limit is just that...the LIMIT. You can run any pace you want down to 45. Use common sense, other than that welcome to the site. Stay safe, and look forward to hearing more from you soon. Again Welcome.

 

Good read coldwar.

 

Use a higher (numeric) gear with a 7004r, unless you still have lockup enabled. Even still, the trans will be trying to burn up the converter whenever the car is below 55. May not be a good thing to lower gearing even more while you are towing this old battle axe up that "Palm springs" hill when it is 110 degrees outside.
Use the largest transmission cooler(s) you can afford for this tow monger.
My opinion.
BTW, Arizona has speed cameras.
You go too fast, make sure your hair is combed, and the wife has on makeup. These cameras can even show your moles.
Jim

 

Not to beat a dead horse. but I have just seen the light on this issue. My car is having the roto rebuilt and should return this week. While in the shop I have had the engine re-gasketed and painted. I had strongly considered replacing the trans but thought better of it from both a cost and curiosity perspective. The car has survived this long without any extensive mods to the drivetrain - why are my needs so different? Only real change I am making is removing the electric fan the previous owner installed and replacing with the shroud/mechanical fan that was OE.

 

Great looking '62 Starfire you have there! May overall be the best looking car GM ever produced. But then having two of them I'm not even remotely unbiased.

 

I have worked through my modification phase on a few Fords that I had. I actually sold one because it was too nice as it sat in stock form. I couldn't bring myself to change anything on it.
One thing that is great about this hobby is that you have all sorts of perspectives. If someone wants to mod the hell out of their car they can have at it. I do believe however that you will lose the flavor of the classic and cheapen the experience of driving one if you change it too much. I have been around the block once or twice and I can tell you that driving today is very easy. Almost too easy

 

You might want to begin in 1940, for a complete understanding of the subject.

From '51 on, all Ford (except Lincoln Hydramatics) and Chrysler automatics had the same quality shifts as their post '65 GM counterparts.

Dynaflow dates back to the '40s. It worked very well until it was replaced by the TH400.

It made perfect sense, in 1938, when it was first used.

If one got "stuck" in sand, snow, or mud, and needed to "rock" the car out, it was easy to move the selector between "L" and "R". Very difficult if "L" and "R" were at opposite ends of the quadrant.

Another piece of history that was unknown until Algore invented the Internet.

And the Introduction of the TH400 had nothing to do with it.

Norm