Hello. First time to post. I have a 73 Camper Special with 390 and getting 11mpg at best. To keep this beauty on the road I need better mileage. I've been advised to swap for a 460 EFI with AOD transmission. Has anyone tried this and got better mileage to make this swap worth the effort and costs?

 

390FE & getting 11mpg?!@#! I would NOT complain about that one bit. Swapping in EFI & overdrive transmission would help.

 

Improve the engine's efficiency with headers, dual exhaust, and dialed-in tuning for more HP and torque. An open element air cleaner and K&N filter is with a few more HP - even on a 2bbl.

Next up is a lower (numerically) rear gear... something like 3.00:1... The alternative to gearing down is an overdrive. Now we're talking a TKO-500 and 4.10 rear gears...A 0.68 overdive will net a final drive ratio of 2.79 which is perfect for freeway flying.

Remember to do an ROI (Return on Investment) analysis to figure out how many miles you need to drive before it is paid for.... At $3.50 per gallon and 11 MPG, that's 31.8 cents per mile. Assuming 16 MPG, it's 21.8 cents per mile. ... and miles add up.

 

Im no expert on 390's, but i can tell you that i dont think a 460 is the answer to your quest for mileage.

ive got 4.10's and the best i've done is 10.25mpg at 65 unloaded. no overdrive though.

it would be possible to find a 460/AOD combo out of a later truck or motorhome, but 10mpg is still a pretty common number for those as well.

soooo ... perhaps you could spend that money on a gear vendor's overdrive?
save the work of swaping motors and trans and still get the OD. set you back $1500 ish?

another option would be fuel injection. Summit has a self learning FI kit for about $1700. that would likely net you some gains as well.

not trying to rain on your parade ... just saying .. they are big old heavy trucks with big old heavy motors .... and they likes them some dino juice ....

good luck!

 

EFI.. a high-dollar item and the last thing I plan to do with my 70 bump after the exhaust and TKO-500/rear gear. It's still up in the air on whether to go with Professional Products' Powerjection or the FAST XFI.. decisions, decisions, decisions.

 

the best my 390 gets is bout 10-11mpgs. she runs real good on a 750cfm q jet.
im on 36x14.50x16.5 w/4.10's

yer best bet is to buy a commuter car.
my .02

kurt
00 f350 7.3 4x4 scsb
99 f350 7.3 4x4 cc lb drw
73 f250 390 highboy np 435- 205
03 getta gli
98 passat
90 corrado

 

11mpg is pretty good!!! FYI a 460 EFI gets about the same!!! Consider replacing the torque converter with a fuel miser from hughes! I picked up 1 to 2 mpg and it really helped.

 

I think 11 miles per gallon out of an f 250 camper special is pretty good. I have an f 100 2 wheel drive that only get 11 and a half. My buddy's 04 f250 with a 5.4 and or only gets 12! If you want mileage I would go with the cummins diesel swap That I have read about on these forums.

 

A lot of good responses...thank you everyone! Changing motors made me cringe since I have only 40K on rebuild. However upgrading the Torque Converter, installing headers, K&N and maybe a good intake manifold would be good to try. Since I'll have the transmission off why not install an AOD? I read the '92 or early '93 is the best for that run. Many upgrades were incorporated to beef it up. Wouldn't that be better than installing an overdrive unit? I believe they are shy of $3K

.

 

There is ZERO OD transmissions that bolt up to the FE engine you have with out a lot of $$$ and time.

 

haven't heard of this...is it manual trans or bolts up to the C6?

 

Excuse me, I see understand what you meant...any OD will be time and expense.

 

IIRC ... the 92 ish AODs where the strongest made in production. In particular the ones found in the HD trucks, or behind the 351w in the F150's had a 2" OD Band, and are generally regarded as the best of the salvage yard find.

AOD Performance Products - Baumann Electronic Controls

BE Controls has a wealth of information available on the AOD/4R70W. They can be made quite bullet proof.

Ford FE to Ford AOD transmission adapter kit

a quick search showed the above site to mate the two together.

One nice thing about doing an AOD swap is the factory column shifter will work because the AOD only has OD.D.1 on the shift pattern. Where by, for racing or towing 2nd can be held by throwing the shifter down into 1 at speeds above 20mph or so. You'd be wise to limit doing this, however, unless you purchase the "fix" from BE Controls (or someone else), because when you hold second in this fashion you WILL lose your OD at somepoint. Ask me how I know ....

if the shifter is thrown into 1 above 20mph or so, the trans goes into second, once the speed drops below that threshold it automaticaly drops into 1st. for controlled upshift you have to start in 1,then bump up to D to allow second, then throw back down into 1 to hold second, then bump back into D to allow third. It's kind of fun once you get the hang of it, but doing so will cost you OD eventually, unless you fix the valve body. again, ask me how I know ...

anywho ... it's a worthwhile swap if you can make it work .....

 

To make an AOD swap work you will need an adapter Ford FE Transmission Adapters its 1500.00 by itself!

 

Transmission Adapter Pricing

850 here .... still a lot of coin ....

makes your return on investment calc harder to pan out.

I think this is something you'd probably do just because you wanted to ... I dont know that it would ever pay for itself.

i'd do a fuel injection kit from summit before i did this swap.

but it can be done ...