71 250 XLT Camper Special. Granny 4spd & 4:11 rear end. Truck to be used as a daily driver. No racing. Not really hauling or towing anything but ya never know. Block is D3TE (stock bore), heads are C8AE-H (no hard seats) and crank is 2U. Here's where I really need some input.

I want to redo the motor for a better setup. I want something that can be a daily driver and have more umph than the 'ol 390 put out. I'd like to stay around 9.5CR but am willing to go above that if it's streetable and has something around 15 or more mpg. (I was at that point already with the current engine until it overheated with a stuck thermostat) If I go to 10:5CR or more, I'd just run it on propane. I've been digging/researching for way too long to decide what to do for stroking the motor and can not make an informed decision. Even though the current engine worked ok, I'd just like a tad more umph.

I don't really want to go oddball in some manner but just want something solid I can rely on for long term and hopefully get some kind of decent mileage/power. I know there's a ton of variables but perhaps someone can shed some light on a direction to go? The one thing I know I'd like is to put a roller cam into it. I'm tired of the clacking lifter scenario. I won't put headers back on but do have dual exhaust. Had to much trouble in the past keeping them sealed. I'd like to have a little thump on the low end but still streetable.

I know this sounds pretty wishy-washy but I'm at a total loss for a direction and am darn sure open for suggestions.

Dan

 

good luck on MPG
my camper special with 354 gears only gets around 12
but it cruises well on the interstate
electronic ignition will help a little
and maybe an electric fan
make sure its tuned and timed properly




or just go diesel

 

I'm not a FE man but there are plenty of them on here.

I hear a 410 is easy to build with factory parts, and runs like a raped ape. If your going for MPG you want a cam with short duration and good lift to fill the cylinders quickly and not bleed off any compression. Also, getting a roller timing set that has adjustment will be good too. Advance the cam for better low end power.

Your 4.11 gears aren't gonna help MPG at all. I'd be looking for something in the 3.5- range.

 

Your wishes/plans are all over the map and don't make sense in terms of your goals.

Foregoing headers leaves efficiency, HP, and TQ on the table. Stock manifolds suck. 4.11 rear gears and a four-speed at 1:1 reduces mpg potential. Go overdrive.

Stay with a two barrel for MPG but you want "ooomph"?

My recipe was EFI /TKO-500 and now up to 18 mpg.

READ:
FE Exhaust Manifolds and Why You Probably Want Headers
CarCraft Magazine: Build a Low-Buck Street/Strip FE
Sanderson Shorty Headers FF427 Reference Pics
Ford FE Smog-Legal Horsepower,Part I
Ford FE Smog-Legal Horsepower, Part II

 

Dan, your truck "71 250 XLT Camper Special. Granny 4spd & 4:11 rear end." is a 6-8 mpg truck. No idea on how bad your engine was tuned a good tuned FE should have plenty umph turning 4:11 gears, while screaming at 65 mph on the hiway.

What kind of budget do you have in mind for your project? Without knowing that you get all kinds of answers.


John

 

Rear axle is a Dana 60, actual ratio is 4.10-1. 'Favorable' ratios available for 1967/72 F250's: 3.54-1 & 3.73-1 .. which would improve MPG somewhat.

4 speed is either the Warner T-18 (reverse is up-towards the dash) or the New Process 435 (reverse is down-towards the seat).

The 410 4V was the standard equipment engine in 1966/67 Mercury Parklanes.

 

You'll find mucho MPG if you up the gear ratio. 3.73 or even 3.50's would be good driver and hauling gears (for the ocational haul).
360, 3 on the tree, 2.75 dallas to ponatoc Ms. 23 MPG with the a/c on in 69 bump. never got out of 2nd gear on in town driving.

 

Tranny is T-18. I put an Edelbrock intake & 4bbl carb on it when I replaced the motor the 1st time. Mileage went up to 13 or 15? hiway. But most driving was +/- 55mph backroads to work and keeping a light foot. Never had any luck with header gaskets/bolts. Are they better than they were in 1995?

Budget is +/- 5K on the motor. Would I be better off just putting an Edelbrock 418 stroker kit and Edelbrock heads with headers in it? I know it's $$$ but I just want something trouble free and bit of go.

After reading suggestions, I'll change the rear end, install electric fan, electronic ign. electric fuel pump. Truck has factory AC but it will get a new 134 change-over from Classic Autoair.

Appreciate all advice and insight... I'm like a 5yo kid at the candy counter that can't make a decision.

Dan

 

I'd keep the mechanical fuel pump. Nothing but trouble comes from electrics.

 

https://www.ford-trucks.com/forums/1...overdrive.html


Installing the NV4500 Overdrive Transmission - Ford-Trucks.com


here is some overdrive trans info
a friend of mine installed a built 700R (gasp) behind his 390 in a Galaxy and loves it
gets around 20-21 mpg on the highway

 

A T18 is a rugged transmission that's good for pulling heavy loads but is not a mileage friendly transmission.

Manual Transmission Identification Guide - FORDification.com

4.10 rear end gears are not mileage friendly either --at least not with a non-overdriven transmission.

An FE engine was designed for plenty of torque for hauling/pulling heavy loads and was built at a time when gas was cheap and people weren't concerned about good fuel economy.

Changes can be made to help performance and marginally increase fuel mileage with the FE but, there isn't going to be any significant or consistent increase as long as the engine is carbureted and the transmission does not have an overdrive gear.

Going a different direction, a 351W has good power and torque as it is, can get decent fuel mileage (15-18 MPG or more), can easily be fuel injected and has plenty of options in being able to bolt up an overdrive transmission without requiring any transmission adapters.

A 351W is 39 cubic inches smaller than a 390. However, there are multiple stroker kits available for the 351W such as 383, 393, 408, 410, 418, 427, 428, 438, 446 or 454 (last four would require an aftermarket big bore block).

Cubic inch-wise, all of these are greater than the 390 but a 351W will also be lighter than an FE --less overall vehicle mass requires less fuel to set the vehicle into motion and to keep it moving. Of course there's also the issue associated with increasing the size or performance of an engine. More power means more fuel consumption to produce the increase in power. Strokers generally aren't cheap to build but, it's just all in what the objective is in what direction you want to go in and what you're willing to spend to get you there.

 

IMO, you should fix 'what you got.' Swapping in another engine like the 351W (not offered in F150/350's until 1981) will be labor intensive and will probably need some work beforehand.

Plus, the MPG gain will be paltry, as these trucks have the aerodynamics of a brick and back then, no one gave a hoot about MPG

1971: Chevron Custom Supreme leaded 105 octane was 35 cents a gallon and this was at a Standard Station in Bel Air CA where I usually bought gas for my 1971 F100 Ranger XLT 390/C6.

 

putting small blocks in these truck is super simple


mounts from later trucks can be used easily
don't forget about 351 Cleveland's
they have some very good heads and make a lot of HP and torque
also small block transmissions will bolt up easily

 

Dan, Something is off, as respectfully as I know how, the truck described above will not get that kind of mpgs being towed on a trailer. Your speedo gear or something is off. I don't mean to **** you off, but I have been around these trucks since they were new. About 8 mpg is about as good as it will get soft pedalling.

Ya gotta slow that engine down to get the mpgs up. With 4:10 rears at 60 mph the engine is screaming.

You can do some porting & polishing on the heads add a rv cam, headers and get power, but you gotta slow it down to get the mpgs up.


John

 

I have to agree with Bill on a no engine swap. I'm not ready to tackle a different engine install at this juncture. Even like Bill said about aerodynamics, it's a beautiful brick in my eyes.

Ultraranger addresses one other aspect, FE weight. I want to keep 'some' of the weight just for the ride. Same reason I kept an 800# gang box in the bed.

John,
No harm/no foul on your answer. Information and advice is what I asked for and I appreciate all responses. Given the extent of the knowledge here, I'd be stupid not to ask for ideas and learn from them. It's been 15 plus years since the truck was running and given my old age (over 60), I could be off as well.

Suggestions I never even thought about, like changing the rear end. Simple & cheap. I considered a tranny swap but the $$ put that on the back burner. Besides, the old granny 4spd is what I grew up with and I'm kind of sentimental.

Dan