I'm putting a 345hp 302 crate engine from ford racing performance parts in my '79 F-150 XLT. I talked to one of the transmission shops in the area and they said the C4 might hold up for awhile but in the long run I could do better with a C6 or AOD. With the C6 or AOD they can swap different gears into the case for lower gears to help me off the line. The C6 sounds OK to me but if I'm spending the money I would want to go to AOD. With the AOD they would be putting a gear set from newer heavy duty trans into the AOD case (I think he said E4ODW? Something with a W at the end) and a stall converter and such. This would get me off the line and still keep me with OD. I don't really need OD because I have 2.75 gears and the reason for the lower trans gears was because of this, maybe I'm missing something?
My question is this: If I'm keeping 2.75 (or possibly moving to 3.25 at a later time) do I need AOD? Will the C4 hold up to 350hp (with a 2000 stall converter and mild shift kit)?
Below are the specs for my truck and some other info:

Engine: "345 hp" 302 crate engine from Ford Racing Performance parts. 345hp produced @ 6500 rpm. The engine is a late model 5.0 explorer block w/ aluminum GT40 heads, an aftermarker type "performance cam" (I can get cam specs when I get home, don't have the catalog with me). I'll be running an Edelbrock Air Gap intake with a 650cfm demon as well as jet-hot coated headers.

Transmission: Stock C4 with column shift. Has been rebuilt once about 4 years ago. Would like to put in a shift kit, 2000 stall converter (maybe a TCI street fighter?), and work with the governor (if I mash on it too much off the line in "D" it shifts to 2nd on it's own. Doesn't do so if I hold it in "1"). From what I understand the factory converter is a 1200 stall.

Rear end: 9 inch ford with 2.75 gears. Open. Would like to add a limited slip. What would running 3.25 gears do to my highway crusing?

Tires: 235/75/R15 on 15" 5 hole chrome dodge van wheels. About 27-28 inches tall (if I remember right)

The truck itself is a 1979 F-150 XLT. It's a regular cab longbed and has about 150,000 miles on it. The only thing thats been rebuilt is the transmission. I drive it daily (about 150-300miles aweek). It leaks oil and burns a little bit too. About a quart every 300-500 miles depending upon how it's driven. Thus the new engine. I live in a rual Texas area so most places I drive have a speedlimit of 50, 55, 60, or 65. I do however like to go fast. I do not do a ton of stop light driving but do want it to move pretty good off the line (are mid to high 13s too much to want? The goal is a daily driver that can run with most anything on the street). I have a bed cover on the bed so that helps mpg as well as reducing drag at higher speeds. It weights about 3500lbs as daily driven (with gas, driver and "stuff"). It has A/C P/S and P/B. The truck currently runs very well at 70mph and seems to get the best gas mileage there. I do not have a tach in the truck but one will be in shortly. I can run 1st to 50mph and that seems to get me to 60mph quickest. 2nd I normally run to about 80 but it has no problems holding to 85mph (ran it to 85 in 2nd at Texas motor speedway during Good Guys) and I'm shifting into 3rd then and after that I don't have any speedo. I know the truck will do every bit of 130mph the way it sits now. The factory engine is rated at 140hp. The smog pump was removed before I got it and I had the cat taken off as well as replacing the muffler with a R/T dakota muffler (free flowing but not loud, my other muffler was getting old and I needed something to get me thru until I do the duals with the new engine so my muffler shop buddy had that so we put it on. really helped out and it's not too loud). The engine currently runs a 2bbl factory carb and redline is about 5500rpm. The truck has front discs and rear drums (I may upgrade to rear discs or cryogenically freeze the drums). I will also be doing a 3/3 drop (with dropped I beams and shackles in the back) to keep the factory rake, make it handle better, and fill up the wheel wells more. Sway bars will also be added.

Anyways thats the gist of it all. If you need more info let me know.

Nick Tosie

 

i would use the c6 and get an external overdrive for it. the aod is not that strong

 

How much torque does that engine put out and when? With 2.75 gears, it's going to bog off the line. I know your thinking of 3.25's, but I'd look for even lower since the 302 seems to like to rev a little. I have 302 with 2.75 gears, too. It's like having a four speed automatic with no 1st gear. From my experience with other trucks, a 3.5 or even a little lower would work much better. I'm sure the 302 would be humming on the freeway, but I bet it would be fine.

I don't know ford transmissions well, but mine has a C6 that has been thrashed hard with no extra cooler and still works fine.