Engine Ideas

[Gage1970]

Im curious. Could I swap a 302 into my 70 f250 highboy and still have a fair amount of torque and horsepower? I don't want to break the bank but I'm fairly confident that a 5.0 would have a little better fuel economy than the 390 in it.

[markguiver]

Too many variables to even give an answer to the question. I would not even consider it for mine because I use it for hauling etc... . I really work the old beast, hard at times. Having the smaller engine may give you less MPG due to it having to work harder to do the same work as the FE that's in it now. You have to factor the torque curves of the 2 engines as well as the wind/rolling resistance of our lifted trucks. Honestly, I could afford a newer truck that may get a little bit better MPG's if I cared about that. I don't own my truck for the fuel mileage, I own it because it's a truck. I had a company truck with a V-10 that got about the same mileage as my Hi-boy. Everything else was equal, gear ratio's, solid front axle, etc. Just some factors to consider before changing engines.
Mark.

[idaho_cowboy]

Not a good idea, at all.

If you need more mpg, the best route is a 300 Six.

You can find a used one locally and do the conversion yourself for probably less than $500 A bone stock one might give you 13-15mpg. Probably better than the 8-10 you have now?

The 302 is not a torque engine. The Highboy needs low-end torque. That's where the strength is, and where you'll find MPG.

Give us more information on your current set-up... Probably lots of things you can do to her as-is.

- Joseph

[cstoyer]

Maybe a 4BT would work for you. Been a couple done and MPG was decent.

cstoyer

[Gage1970]

Not a good idea, at all.

If you need more mpg, the best route is a 300 Six.

You can find a used one locally and do the conversion yourself for probably less than $500 A bone stock one might give you 13-15mpg. Probably better than the 8-10 you have now?

The 302 is not a torque engine. The Highboy needs low-end torque. That's where the strength is, and where you'll find MPG.

Give us more information on your current set-up... Probably lots of things you can do to her as-is.

- Joseph

It's a 1970 F-250 390 swapped in 02 by previous owner. 4.10 gears np235. Dana 24 t case. Besides the motor it is stock. Back in it's prime it was used by Quinn's well drilling in Oregon.

[idaho_cowboy]

So 390, Np435, Dana 24, and 4.10's All pretty standard.

With the above setup in a '69 Highboy, and 31" tires my best average MPG has been in the 15mpg range, with a highway of 17mpg.

But there's lots of small factors.

Which carb/intake ?

What's the exhaust?

HEI or Points?

Let's start there..
- Joseph

[Gage1970]

So 390, Np435, Dana 24, and 4.10's All pretty standard.

With the above setup in a '69 Highboy, and 31" tires my best average MPG has been in the 15mpg range, with a highway of 17mpg.

But there's lots of small factors.

Which carb/intake ?

What's the exhaust?

HEI or Points?

Let's start there..
- Joseph

Eldebrock intake carters afb 4 barrel. Points. Stock exhaust.

[Gage1970]

Maybe a 4BT would work for you. Been a couple done and MPG was decent.

cstoyer

I would love to do a 4bt. But I can't find one and I don't have the money. Unless you would like to do it for me.

[idaho_cowboy]

The FE series engine is a wonderful power-plant. It would be a great dis-service to pull it out and put in a small block.

If your engine is a runner, keep it!

That carb is probably a 625 cfm carb or something close to that, which is a great fit.

If the engine is healthy, no smoke, doesn't burn oil, good oil pressure, etc., etc. Here's what you should do..
Firstly tune. Good clean spark. I like Autolite 45's. 8mm Wires are good, but not required. Double check for healthy cap/rotor and points are to spec. Run 12 degrees initial if you can get away with it. If at any point you ping under load, retard 2 degrees at a time. Should be NO ping.
Double check for clean fuel. The filter at the pump plus one inline clear filter is great.

An Edelbrock calibration kit will do wonders in the tuning department. You can experiment with jets, metering rods, and springs. But it's a fine science, and is going to take a lot of experimenting. Read up on properly tuning a Edel/Carter carb and decide if you want to try it or not.

Double check that your transfer case, tranny, and both differentials have decent clean oil, and aren't running dry. See factory specs for which fluids go where.

Make sure your cooling system is working correctly. 180-200 degrees is a good max water temp.

Now after all of that.

Biggest gain bolt-on is going to be exhaust. This will give you an immediate 2.5mpg increase if you don't change your driving habits. Of course, it's going to sound better, so your foot will probably be in it more too. But try not to for the sake of testing!

1.) Hooker Headers.
Here's the set that fits a Highboy:
https://www.summitracing.com/parts/hok- ... e/5-9l-360
Blast them to remove the stock flat matte coating. As it's junk anyway. And re-coat with VHT Flame Proof primer, Followed by Flame Proof Black. This will preserve the tubing, and will FAR outlast the original hooker coating. And is still cheaper than going ceramic.

Use these gaskets:
http://catalog.remflex.com/FORD_Header_ ... p/3009.htm
Pricy. But worth it.

Mix some acetone/ATF for a pre-soak on your stock exhaust manifold bolts. Soak for a day or too after applying with a spray bottle. If you're lucky, you won't break bolts in the head.

Now after the headers go on, you're going to need a fresh exhaust system. 2.5" collectors and 2.5" all they way back each side with an H pipe would be perfect. You could get away with 2", but 2.5 will sound more mellow. I prefer chambered Flowmaster 40 series for clean flow and sound. They actually flow better than a thrush/glasspack or similar "flow" through muffler! Glasspacks are the worst on MPG.

The exit on both sides need careful attention. Don't just stick them straight out the back. But also don't do the stock style right out the side either. For optimum performance the angle on the tip needs to be around 45d to the movement of the truck.

Here's a quick illustration, never mind the scale!


This will allow the airflow when your going down the highway to actually scavenge your tailpipe rather than create non scavenging turbulence. The flow from the muffler back to the tailpipe is already compromised. Why make it worse with a lousy exit hole? This mod is worth a solid 1mpg on the highway.

2.) Dual Belts
Don't laugh!
Regardless of if you're using a flex-fan, clutch fan, or the stock steel fan, you need dual belt pully's. Alternator/Waterpump/Crank at least. If you don't have dual belt pully's, start looking for some. When you do have them, have the autoparts store order a matched set. They need to be matched as close as possible. This is a really great mod, and it does make a difference.

3.) Tires
Depending on the mission of your truck, tires might vary. All-around BEST highboy performance in all working conditions are going to be 31-33" tires, and the narrower the better. Trust me. The narrower the better. Memorize this.

For optimum performance when working, towing, or driving down the highway. Get some all-season E-rated 235/85/16, or at the largest 255/85/16 tires. Run around 45psi when unloaded, and up to 65psi if towing or hauling weight.

A big fat mud tire isn't going to do you any favors, anywhere. If you must get mud style tires the only ones worth their cost are TOYO MT's, or the ones from Firestone. Either way stay narrow! Unless your only mission is play.

All of the above should turn your highboy into a solid 13.5mpg average rig when considering all driving conditions. And you might get 15mpg on the highway if you keep her around 60mph. (No reason to go much faster with 4.10's).

I've owned 7 FE powered Bumpside highboys. Taken numerous road-trips, and working with them under any given circumstance imaginable. Towing, hauling, racing. You name it. Better mileage CAN be done. It just takes some good old fashioned work ethic, and common sense.

If you're getting 8mpg now, and you go to 13mpg that will save you around $375 in fuel per 3,000 miles. (per oil change). So in two oil changes all of the above will pay for itself.

Good-luck!

- Joseph

[eggman918]

Maybe a 4BT would work for you. Been a couple done and MPG was decent.

cstoyer

I would love to do a 4bt. But I can't find one and I don't have the money. Unless you would like to do it for me.

I get 18 mpg with the 4BT towing @ 70mph in my '68 truck weighs 8,000# and trailer is 3,,500# did the ZF-5 and 3.55 gears with 33" tires, turns 1950@75mph. Best mod I've done inthe 26 years I've owned the truck

[Gage1970]

The FE series engine is a wonderful power-plant. It would be a great dis-service to pull it out and put in a small block.

If your engine is a runner, keep it!

That carb is probably a 625 cfm carb or something close to that, which is a great fit.

If the engine is healthy, no smoke, doesn't burn oil, good oil pressure, etc., etc. Here's what you should do..
Firstly tune. Good clean spark. I like Autolite 45's. 8mm Wires are good, but not required. Double check for healthy cap/rotor and points are to spec. Run 12 degrees initial if you can get away with it. If at any point you ping under load, retard 2 degrees at a time. Should be NO ping.
Double check for clean fuel. The filter at the pump plus one inline clear filter is great.

An Edelbrock calibration kit will do wonders in the tuning department. You can experiment with jets, metering rods, and springs. But it's a fine science, and is going to take a lot of experimenting. Read up on properly tuning a Edel/Carter carb and decide if you want to try it or not.

Double check that your transfer case, tranny, and both differentials have decent clean oil, and aren't running dry. See factory specs for which fluids go where.

Make sure your cooling system is working correctly. 180-200 degrees is a good max water temp.

Now after all of that.

Biggest gain bolt-on is going to be exhaust. This will give you an immediate 2.5mpg increase if you don't change your driving habits. Of course, it's going to sound better, so your foot will probably be in it more too. But try not to for the sake of testing!

1.) Hooker Headers.
Here's the set that fits a Highboy:
https://www.summitracing.com/parts/hok- ... e/5-9l-360
Blast them to remove the stock flat matte coating. As it's junk anyway. And re-coat with VHT Flame Proof primer, Followed by Flame Proof Black. This will preserve the tubing, and will FAR outlast the original hooker coating. And is still cheaper than going ceramic.

Use these gaskets:
http://catalog.remflex.com/FORD_Header_ ... p/3009.htm
Pricy. But worth it.

Mix some acetone/ATF for a pre-soak on your stock exhaust manifold bolts. Soak for a day or too after applying with a spray bottle. If you're lucky, you won't break bolts in the head.

Now after the headers go on, you're going to need a fresh exhaust system. 2.5" collectors and 2.5" all they way back each side with an H pipe would be perfect. You could get away with 2", but 2.5 will sound more mellow. I prefer chambered Flowmaster 40 series for clean flow and sound. They actually flow better than a thrush/glasspack or similar "flow" through muffler! Glasspacks are the worst on MPG.

The exit on both sides need careful attention. Don't just stick them straight out the back. But also don't do the stock style right out the side either. For optimum performance the angle on the tip needs to be around 45d to the movement of the truck.

Here's a quick illustration, never mind the scale!


This will allow the airflow when your going down the highway to actually scavenge your tailpipe rather than create non scavenging turbulence. The flow from the muffler back to the tailpipe is already compromised. Why make it worse with a lousy exit hole? This mod is worth a solid 1mpg on the highway.

2.) Dual Belts
Don't laugh!
Regardless of if you're using a flex-fan, clutch fan, or the stock steel fan, you need dual belt pully's. Alternator/Waterpump/Crank at least. If you don't have dual belt pully's, start looking for some. When you do have them, have the autoparts store order a matched set. They need to be matched as close as possible. This is a really great mod, and it does make a difference.

3.) Tires
Depending on the mission of your truck, tires might vary. All-around BEST highboy performance in all working conditions are going to be 31-33" tires, and the narrower the better. Trust me. The narrower the better. Memorize this.

For optimum performance when working, towing, or driving down the highway. Get some all-season E-rated 235/85/16, or at the largest 255/85/16 tires. Run around 45psi when unloaded, and up to 65psi if towing or hauling weight.

A big fat mud tire isn't going to do you any favors, anywhere. If you must get mud style tires the only ones worth their cost are TOYO MT's, or the ones from Firestone. Either way stay narrow! Unless your only mission is play.

All of the above should turn your highboy into a solid 13.5mpg average rig when considering all driving conditions. And you might get 15mpg on the highway if you keep her around 60mph. (No reason to go much faster with 4.10's).

I've owned 7 FE powered Bumpside highboys. Taken numerous road-trips, and working with them under any given circumstance imaginable. Towing, hauling, racing. You name it. Better mileage CAN be done. It just takes some good old fashioned work ethic, and common sense.

If you're getting 8mpg now, and you go to 13mpg that will save you around $375 in fuel per 3,000 miles. (per oil change). So in two oil changes all of the above will pay for itself.

Good-luck!

- Joseph

Thank you for all this great info. I'm a 16 year old I bought the truck last summer because I've wanted one for as long as I could remember. I didn't take into account that I would be driving around 40 miles to school and back (running start program. College in high school). And I don't want to get rid of it. It's still a project sorta, but as cash flows in from my job at the race track I'll work on doing some of these modifications. Thanks

[eggman918]

When i was doing research after my 390 died the EFI 300" I-6 with a 5 speed OD was the other option I was looking into but i found a deal on a running bread van with the cummins for a fair price so it won, but the EFI 6 and OD trans could be a viable option especially if your 360 has some life in it still.
If you take your time you could likely find a donor vehicle for a good deal, with the divorced T-case a 2WD will work you will need to shorten the intermediate shaft as either the ZF or the M5odr2 are longer but there is room to do it. the ZF has more truck like ratios with 1st being a bit of a granny gear at 5.72-1 the M5odr2 is a close ratio with a 3.91-1 1st gear......