Low tech vehicle approach

[Knighton]

I am considering going low tech concerning a vehicle (truck) to be used daily or as a back up. I remember grandma and grandpa had a 1965 Ford Galaxy 500 with a 390 motor. Grandpa never changed the oil - just topped it up. This car use to start in any weather (-40C), never being plugged in; the thing was bullet and bomb proof. Today's vehicles, with their supercomputers, are anything but reliable. Here is what I propose to do.

My last remaining grandparent has a 1985 Ford Bronco (351 W) with a three speed. It gets about 5-7 mpg! No kidding. It has been checked out by more than one mechanic and they say it is running fine. The Bronco has around 130,000 kms so all around it is in good condition. I propose to have an engine custom built by a respected engine builder. I am thinking a high hp, easy revving (6500 rpm) 302 producing 350hp/350 tq, which would surely see these hp and tq figure peak at higher rpm - not great for towing though but wait. I would put in a 6 (or 5) speed ZF gearbox and lower the gearing right down. I could go with a 351 or a stroker (to 396 or 408) but this surely see fuel mileage suffer. The motor would be carbed and built to be bomb proof. The Bronco itself has no power windows or locks but does have cruise and air con.

I would select the gear ratios from the manufacturer. The first 2 gears would be low for pulling a camping or horse trailer. All gears would be closely spaced. 1st gear would not be used for daily driving. Having a 6 speed gear box would make for a nice tall highway gear.

My question is:

What kind of cam to use? Should I build the engine to be a stump puller (mild cam) and go with a normal set of gears? Or, should I not worry about using a mild cam and use lower gearing instead to create a strong low rpm puller and consequentally, a nice highway cruiser and daily driver with the choice of 6 speeds?

Do you recommend automatic or manual?

Manual could see me use 3rd off the line, 4th for city driving and 6th so highway cruise. 5th would be used for highyway passing?

Your thoughts?

[EarlAbsher]

I've built some pretty fast engines. A great source for this answer would be Summit Racing. The techs their are great!

1 800 230-3030 or summitracing.com

[TMR2003]

Enginefactory has some good ford engines. There ford engine page is at www.fordcobraengines.com. I hope this helps.

[John]

if you plan to tow a trailer, I'd say go with a shorter cam and build it into a stump puller. If you do go with an auto trans, you'll probably want to use a tighter torque converter for towing as well (also use a trans cooler). Manual trans will give you an extra gear or two to play with and is just more fun in my opinion. [img]/ubbthreads/images/graemlins/smile.gif[/img]

I'm no expert though, just my 2 cents. Good luck with it.

[Bill Bayard]

Knighton,

If gas mileage is a concern, you might want to think about
a 4 spd automatic(overdrive). With the proper diff ratio, and a moderately tuned engine, you should still have plenty of power for towing, and get a LOT better than 5-7MPG! Shifting can be fun, but not necessarily when towing a trailer on a long road trip!
Many years ago, I had an F-150 with a B&B 429, 4spd, etc. It was a son of a bitch on the highway! My 1981 Bronco (tame 351W & automatic w/overdrive) was a pleasure to drive, didn't kill me at the gas pump, and would still pull down a house. When towing in hilly areas, I'd just lock out the overdrive.

Bill

[Knighton]

Hi Bill,

Will a 4 spd automatic give better mileage than a 5 or 6 spd manual?

I am not sure what the diff ratio is.

Would you go with a shorter cam (stump puller) or would you go with shorter gearing?

The vehicle would be used sparingly to tow. Most use would be a daily driver - say 10% towing and 90% daily driving.

What are the options for a tip-tronic gearbox? ZF make one? I know Porsche does.

[Jim B]

One thing to consider with the Bronco sitting at the curb, average over 5K lbs. The 302s work HARD to move that heft. Add in towing and the 302s are out of their league
With the mileage you stated it may be possible that the Bronco came with 4:09/4:11 gears. Most were 3.55/3.50, but the 4:09/4:11s were an option
For what its worth my EXP with the Bronco’s are,
1984 351W 2bbl C6, run at 55mph would pull 12-14 mpg at 65mph, 10mpg, 75mph, 8mpg I drove it a lot at 55 owned it for 110k miles.
1979 351M C6 5mpg no matter how fast tips the scales at 5900lbs and is a dog, has an EFI460 in its future. 330K miles.
1989 302, AOD. Factory stock truck. When AOD was tight it managed 16-18 mpg. If a ran it hard it would run 13-15, all time best tanks 24.1 mpg I90 in SD heading twords Sioux Falls From Rapid, 40mph tail wind 65mph, 20.0mpg Wash DC to Warrenton Va 57mph average.
Current mpg is ~12 with 250K miles. The 302 is ok at speed has issues with the mountains, and do not expect a brisk take off.
For towing the Auto is nice, Baumann engineering can help if you want a computer-controlled tranny. The AOD is OK but should be beefed up if you’re going to tow. Most of the mustang parts for it eliminate the lockup feature. AODE is much better, but requires controller. E4OD- $3K+ to play with + controller at stupid $$$$. The 3spd C6 is all but the definition of Bombproof but it spins the engine on the highway.

The following is for stock availability, if your going to use custom built/geared skip this paragraph

The ZF5speed out of a F350 is very nice, but runs a deep first gear. The light duty Mazda MOD 5speed is a POS avoid it like the plague. I understand you mentioned the ZF, the Mazda 5speed is found almost everywhere, and almost all of them appear to have been run dry which is the only reason I brought it up
ZF 5speed. 2nd for take off, 3-4 around town. 5th is an OD and feels like it. With a 302 you will use 1st for take offs just due to the weight of the Bronco.

Go with the 351W, I think you will be happier in the end. Even at stock displacement, they work better than any of the 302 variants. The mileage penalty works out to be in the range of 1mpg difference to the favor of the 351W depending on use of the secondaries [img]/ubbthreads/images/graemlins/grin.gif[/img]

Jim