[connoisseur]

Hi guys, I have a 78 Ford Fairmont 2dr sedan, 77 460 from a Mercury Grand Marquis, (internally stock - 8.2 compression), has headers, Edelbrock Performer intake & 750 carb., alum. rad., with a built C4, 2,200 rpm stall, (which I didn't want, wanted 1,700-1,800, but was later told that only a 10" converter would fit with the J. Bellhousing/adaptor), and a 3.08 gear. It is rather sluggish around town at anything less than 3/4 throttle. Gas mileage went from about 11-12, (with the previous 3.27 gear), to about 7.5 with 90% hwy cruising 65-70mph. I like the way it cruises on the hwy now, the rpm's are about 290 lower,( also went from a 26" rear tire to 27").
Can't live with the sluggishness around town. Wondering if I need to switch to a 3.55? I know I won't like the rpm's on the hwy, that is why I went from 3.27 to 3.08.

Also, I plan on installing Edelbrock alum heads and a comp cam, (270?)next year, wondering if I wait until then to change the gear, if I can get away with just going back to a 3.27? Car weighs about 3,300 lb.s

[whyholdback]

Let's pretend for a second that your Fairmont was a '79 Mustang, then pretend that was an '82 Camaro with a 7.9:1 454. Now I can tell you this: Getting 20 MPG with good launches is possible with a 3.08:1 gear and 26" tires by swapping to a 700R-4 and using a Comp cam with a 206-at-0.050 intake lobe and a 110 lobe sep. That's far milder than the cam you want, but feeling quick means more to me than actually having lots of HP.
Next, if you've adapted a C4, then you can swap to an AOD, which is not inherently weak, but has a few problems that need fixed. Easier to read up on how to swap a late 4R70W from a '95 Mustang 5.0, or better yet, from a '99? Explorer 2WD 5.0, but those guts can be retrofitted to give an AOD the better ratios, however, you lose the late 4R70W's superior lockup, and in fact you lose the lockup converter entirely, when you put the 1-piece input shaft into the AOD. So again, you're losing MPG, and still don't have the launch of the 700R-4. Which is why there is an adapter for 460-to-700R-4
Sell the C4 and the adapter, then buy the adapter for the 700R-4, then use the '88-'93 700R-4.
Then, once it drives right, you can start thinking about saving up for a new cam / converter / rear gear combo.

[TommyK]

Before you swap gears swap out the original retarded timing set with a pre 72 straight up timing set.

Recurve your distributor.

These two simple things will make a big difference.

Of course if you change the timing set, a cam change isn't that much more work.

[tnsmith10]

Originally Posted by connoisseur

Hi guys, I have a 78 Ford Fairmont 2dr sedan, 77 460 from a Mercury Grand Marquis, (internally stock - 8.2 compression), has headers, Edelbrock Performer intake & 750 carb., alum. rad., with a built C4, 2,200 rpm stall, (which I didn't want, wanted 1,700-1,800, but was later told that only a 10" converter would fit with the J. Bellhousing/adaptor), and a 3.08 gear. It is rather sluggish around town at anything less than 3/4 throttle. Gas mileage went from about 11-12, (with the previous 3.27 gear), to about 7.5 with 90% hwy cruising 65-70mph. I like the way it cruises on the hwy now, the rpm's are about 290 lower,( also went from a 26" rear tire to 27").
Can't live with the sluggishness around town. Wondering if I need to switch to a 3.55? I know I won't like the rpm's on the hwy, that is why I went from 3.27 to 3.08.

Also, I plan on installing Edelbrock alum heads and a comp cam, (270?)next year, wondering if I wait until then to change the gear, if I can get away with just going back to a 3.27? Car weighs about 3,300 lb.s

what is this j. bellhousing/adapter? is it a adapter plate or a bellhousing that bolts to the front of the trans?
if its an adapter plate, the mention of the AOD is not a bad idea, third gear will suck though as because of the converter design but, should work just fine. and you could go back to the shorter tire and gearing as well.
if its the bellhousing itsself, i dont see why a stock c-4 v-8 converter wouldnt work. transtar has a converter that is a 10" low stall with the extended pilot that fits the 460. converter # FM122. they also have another low stall without the extended pilot, part # FM120. hope this helps.
also, if you plan on doing these changes, the higher stall converter may actually be an advantage later when you do the cam swap.