While the engine and trans are out, I'm trying to decide if the AOD is worth the effort. I've searched the site and found that the swap is sort of a toss up. Locally, I cruise on the interstate around 70 mph (but not yet in my mustang). If I keep my C4 with the 3.0 gears that I currently have, what should I expect my RPMs to be at while driving at this speed? I planned on sticking with the 3.0 gears because I was advised that this is a good freeway gear ratio, and I plan on driving this car quite often. Now, nothing is written in stone, yet, so any information would be appreciated!
Thanks

 

What kind of tires do you have? What kind of engine/cam/intake/carb? What kind of converter are you running?

A manual with 245/45-17's (also a typical tire height for the newer classics) would put you around 2750 rpm. An auto with a stock stall would be a little higher, 3k or so, but that really depends on how tight the converter is.

 

i'm running a stock 289 4V with a (theoretically) stock C4. As far as the converter goes, this is an area I'm not too familiar with yet. I guess I would go with something as close to stock as possible. What does a higher stall converter do vs. a lower stall converter? I'm not going to drag race this car or anything like that, however good passing ability on the freeway is a must around here. 3 grand seems high to me for a V8, especially a 289. Hmmmm. . . .

 

I would'nt think 3000 is to hard on the engine...but it will be hard on your wallet....I can hear the gas pump from here. My neighbour wanted to increase his milage on his bronco, and he put a GM overdrive tranny in his Ford...I know...Blasfamy!...but he did it. He bought a conversion kit and with block adapter plate for aGM 700R with lockup converter and overdrive...he says he turns1900 at 65mph.

 

i have a c4 with the 3.00 gear - at 70, i'm exactly on 3000 rpms.

 

+1 with same set up.

 

Your buddy must have had that trans around because the AOD will get you a little better gas mileage. You can make any trans better on gas mileage if you put all the right parts together, gear, tire, converter... Hope this site can help you decide...http://www.4lo.com/calc/gearratio.htm

 

If you want to get into the 2K RPM range at 70 MPH on the freeway, you have to go with an AOD. Or pull that C4 out and go with a T-5 instead. Don't even think about a C-6. It's a 3 speed auto as well. Or, suck it up and keep that C4 in there and get 12 miles per gallon.