Slick 60's

Even though gas is not at 4 dollars a gallon now it likes it too much so I really can not drive it as much as I would like so I am questioning my sanity on installing it,I am thinking a 351-W would have been a better choice so I am going to hunt for a running motor this fall and get it in over the winter. I have a good small block C-6 and mounts in a 78 parts truck so all I need is a motor.

Realistically you don't install an Fe for good mileage, that's a 6cyl or 4cyl job.
And you didn't build that camper special to be just another daily commuter, did you?

It's yours, do what you think is best.

But right foot training is the best way to tame any Fe of the thirst.
Of course you will not be smiling near as much, when your passed by several 1800 lb econo boxes wound for sound..

460 is a 385 series engine. I can understand wanting better fuel mileage. Other than a engine swap would a taller gear help? What's your driving style? If you drive aggressively then a motor swap wouldn't help much. What kind of mileage are you getting out of the 460 anyway?

Realistically, how much do you drive it? 351 is not a great mileage engine either.

How long will it take to recover the expenses of another engine/tranny, exhaust, plumbing and wiring changes? My guess is drive it and enjoy it, you will probably never recover your expenses of the engine swap.

If anything, look at electronic ignition, carb tuning, maybe a good torque cam and keeping your foot out of it (most of the time or what's the use of having a 460?).

You would probably be better served to put an overdrive tranny with a lockup converter behind the 460 and enjoy life.

JMO,
SPark

It has 2.75 gears so the motor is not spinning very fast and really did not improve the gas mileage much over the 3.54s when it was a 3/4 ton,I think its getting 10 to 12 miles per gallon and does better then the original 352 but I would like it a little better. I had planned on doing some serious hauling with the truck towing a car to long distance shows but realized it would be cheaper to just drive the car and putting a o/d trans behind the 460 was too expensive so I converted to a half ton with highway gears and disc brakes for way less then a auto or manual o/d trans would cost. I do not need that big of a motor in it for how I drive so maybe a 302 would be best and put the 460 is something that needs the power,my plans for the truck is to drive to long distance swapmeets so gas mileage is more of a concern then brute strength.

My truck was/is built specifically to do 4000 mile round trips to Slickstock
. Hopefully someday it will do just that, it has a 302, 4 spd Od tranny and 3.50 gears. So I would tend to say yes, for what you want a 302 will do 'er.

Have you thought about a 300 6? I've had 302's and I'd prefer the torque and fuel mileage of a 300 over a 302.

What about a mod motor out of a more recent truck, like a 5.4? These have a lot of power and get better mileage. You could probably find and engine and transmission. I know the wiring can be intimidating, but it might be the best bet for mileage. I had a 2000 F350 that weighed in at 7000 lbs empty that got 17+ at 70 MPH with a 5.4 and auto OD. I think the 16.5 tires that ran at 90 PSI also helped.

I have been thinking about a 240 or 300,years ago I had a 77 f150 that someone put a 66 240 in it and I got close to 20 on the highway with it.

A 300 and T5 with 3.7 gears can get 20mpg. My 67 did that for many years.

I had a friend who had a bone stock 85 f150
300 & a 3 spd... Not sure of the gears
We drove it one summer on vacation
Highway miles.. He never got less than 22 mpg
But you could put a egg between his foot & pedal
And he wouldn't have broke it

I hate to give up the power but want to drive it more and spend less on gas so I am going to look on craigslist this fall for something less thirsty,since it has a almost new dual exhaust it will most likely be a 302 and a C-4.

Have you tried rejetting the carb? If it were mine I'd buy a wideband air/fuel ratio gauge and get it running in the 16-16.5:1 range at light throttle and 12.5-12.75:1 at full throttle. I'd be willing to bet that it's running way richer than it needs to be.

The wideband I use:

https://www.summitracing.com/parts/inn- ... gQod3n8L_Q

Nowhere near the same thing as your truck, but I have a '64 VW that at the time had an all-stock '72 dual port engine installed. Still had the original 34mm single barrel carb. I was getting 24 mpg with a heavy foot, mostly highway and interstate mileage since I was commuting to Greenville Tech at the time. VW advertised that their cars got "an honest 25 mpg" so it was getting normal mileage for a stock engine. I added a pair of two barrel 36mm Dellorto carbs and tuned them and it picked up to an avereage of 32 mpg, and had a best of 36.25 highway mileage. I even ran it as hard as I could for a full tank, all city mileage running errands for work and it still got 28.5 mpg. Same engine, bigger carbs, way more power, and much better mileage. It would be worth spending $150 bucks on a wideband gauge to see where you're at before you spend hundreds/thousands on an engine swap.

We had a 1978 F150 with a 6 did pretty good on gas. We had an automatic 76 f150 with 460 and would pass anything on the road except a filling station. Friend reminded me when bemoaning my Chevy 1 ton mpg , "you bought the truck to haul and pull, not for gas mileage" . He had a point. Build a truck to suit your needs, but remember you are pushing some serious iron down the road. My 80's Chevy 1 tons weigh 6500-6800 pounds and get 12-14 mpg. My 84 S10 with 2.8 V-6 gets 24 tooling around empty. Run what you like. Mark

66camperspecial wrote:Even though gas is not at 4 dollars a gallon now it likes it too much so I really can not drive it as much as I would like so I am questioning my sanity on installing it,I am thinking a 351-W would have been a better choice so I am going to hunt for a running motor this fall and get it in over the winter. I have a good small block C-6 and mounts in a 78 parts truck so all I need is a motor.

Look at swapping to Quadra Jet. With your high gear ratio closing the throttle too much on a Holley will overcharge the idle circuits and pull more gas. Leaving it like it is with a Rochester will have better mileage. I am an a learning curve on custom tuning these carbs, but maybe someone who knows them better will give tuning advice. Find or make a dual plain adapter for the QJ.

The 460 has a Edelbrock on it right now.

I have to ask, just how much are you driving the truck now? Fuel is not going to get any cheaper, but cost of changing engines may be more than what you save. I have to ask if the engine you have in the truck is a used engine you transplanted or was it rebuilt when installed. You may need to learn more about the 385 engine series, and how to improve one for better mileage. Not a cheap endeavor though. Just installing another engine of unknown condition (used) may not help at all. I owned a 1 ton window van that I hauled parts to Carlisle PA. with. Had a C6 and got 14 to 15 mpg on the road. This was the 4 barrel high output stock engine. Only used it for swap meets. As to pulling any large amount of weight with a 302, it's possible but I wouldn't want to. A 300 six is a fine engine and built for torque, but I've seen those eat gas also. As to any engine, if I were going to change engines, and try for mileage, I would purpose build it.

66camperspecial wrote:The 460 has a Edelbrock on it right now.

Look into rod and jet combinations and see if a 2 stage accelerator pump spring exhist. There might be a way to limit the plunger at cruising throttle. They are fairly simple to rebuild but at this point that is where my experience I have with Edelbrock carbs.

Pulled a plug and it looks like its a little on the lean side so I think this motor just likes gas so its time for a smaller motor.