can I change an old p/u from 3/4 to 1/2 ton?

[john keyes]

I have an old 3/4 ton chevy pickup with the eight hole wheels and giant rearend 

Can I change it over to a 1/2 ton, ie with a lighter rear end and spindles in the front to have 6 holes all around?

-are the control arms and spindles in the front different for 1/2 and 3/4 ton?

-driveshaft yoke etc might be a problem?

just looking for  a little improvement in mpg

[Graybeard]

You must have missed a previous discussion we had on buying a new truck for better mileage as false economy. The same applies here. Can it be done most likely but the cost of the conversion would pay for your gas for the next several years in the current truck. Such attempts to save money are a wasted effort and in the end only cost you more dollars than staying with what you have.

[quickdtoo]

I'd just buy a small used truck for the money you would have invested in the change which wouldn't be cheap unless you do the work yourself, even then I don't think it would be worth it in your scenario. I had a '69 Ford F150 V8 in 1970, it got 12-13mpg whether I drove it fast or slow, hard or easy, it made little difference.

As far as buying something that's more economical as opposed to just driving the gas guzzler, the money spent on gas is just a hole in your wallet, at least you can own the econo vehicle. Here's a Clark Howard recommended calculator to help figure it all out.

Tim

http://politicalcalculations.blogspot.com/2006/04/should-you-trade-in-your-gas-guzzler.html

[30-30man]

Forget the conversion...It'll cost more than the truck is worth.  You have a decent truck , you just need to adjust a few things.  Air the tires at maximum pressure, you can find this on the side of the tire.  Don't go by what is written on the inside of your door.  This only pertained to the factory tires which have obviously been replaced already.  Get a tune up with some plugs, filters, wires, etc.  The last thing is to get the carb running as lean as it will run.  I had an old 78 f150 with a 351m that went from 10mpg to 15 with just a carb tuning. It was so lean, it whistled all the time but it got much better mileage. It looks like you already have headers so the exhaust is fine.  If you haven't already, lose the cat or gut it. That is about all you can do. 

If you try converting it you would have more than $2000 bucks in parts.  With that amount, you could buy a small 4 banger that is well used.
If that doesn't work.....................
 The best thing you can do is stay home more. I wish more people would do this so we all could get a break with these crazy fuel prices.

[Lloyd Smale]

on a chev of that era it certainly can be done. back in the day we used to do just the opostite. Wed convert our 1/2 tons to 3/4 tons as we all ran 40-44 inch tires and the 1/2 ton gear woudnt hold up and axles would break like toothpicks. I did two of them and it wasnt that bad of a job. Will you save gas? maybe a little but dont expect anything drastic. Certainly not enough to justify the conversion even if you get the parts for free. Most of the old 3/4 tons ran 410 gears and about the lowest you could get in a 1/2 ton is 373s so there will be some gas savings there but at the expense of power and most of the old trucks were seriously lacking in power and needed the gears. Would i do it? Hell no. Id bet an old 3/4 ton in good shape would bring enough on the market to buy a truck that is better on gas. If you are flat in love with your truck and want to increase the mileage and its in good enough shape to justify the work youd probably be better off to retrofit a fuel injection system. Lots of old iroc cammeros in the dump with tuned port injection. If you look you can find a whole set up with the wiring harness and computuer farily cheap. We just did the neighbors boat and it cost him 500 bucks total with him and i doing the work and we did it in two days. Bottom line is especially with the older trucks your asking what is basicaly shapped like a brick to go down the road and no matter what you do your not going to get great gas mileage.

[Empty Quiver]

With enough cash you could turn it into a Peterbilt. I couldn't help myself.  Try using lighter synthetic axle lube, if stick do same in trans. Radial tires have lower rolling resistance and blow them up tight. Tune engine to very edge of lean condition. Drive so conservative it embarresses you. I just did math on 24k a year 14 mpg $4 gas VS. 22mpg and 29 mpg. It's roughly $200 and $350 a month difference. I'm going to keep the Expy for its intended duty, and get a cheaper commuter. Heck how many people have a $25,000 boat they use 20 times a year or a motor home they put 400 miles on a year. I can have a quickly depreciating truck on the place for the times I want/need it, it's paid for and is still in very good shape. Long way of saying park it and get a $2500 car that gets good fuel economy, use truck when you have to.

[john keyes]

okay guys, I resolved the issue:



































yessir, 82 F100 300 six.

paid $600 for it this morning.

guys, thanks for the replies, see ya around the GBO.

also Graybeard, your place is the best, keep up the good work.

[R.W.Dale]

 the ford 300 six is one of the most outstanding engines of all time. BUT if you're expecting it to get much better mileage than your 3/4 ton then you're in for some serious disappointment

[Hairtrigger]

Your new truck costs less than a 3/4 to 1/2 ton conversion.
That inline 6 is darn near indestructable... we used to have one in a old, light grain truck.

[Lloyd Smale]

A 300 6 in a 1/2 ton 2 wheel drive should get 15-18 on the road which is a substatatial gain over what your going to get with a 3/4 ton chev 4x4. My old 3/4 ton would get about 12 down hill with a tail wind. the old 300 6s that were fuel injected tend to get as good of milage as the newer fords with a v8

[R.W.Dale]

the old 300 6s that were fuel injected tend to get as good of milage as the newer fords with a v8

but an 82 will not be fuel injected nor will it have an overdrive

[Lloyd Smale]

very true. I dont think they did till about 88