300 in a f-250 any good?

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Dashman
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300 in a f-250 any good?

Post #1 by Dashman » Fri Jan 12, 2018 12:23 am

Hi everyone, new here and looking to get some advice. So how would a 300 perform in a 1973 f-250 4x4 with 3.54 gears? Would I be able to get 18 mpg doing 65 mph?could I pull 5-8000 lbs comfortably doing 60 mph?
if not how could I achieve this?

Cheers, Ty

tnab1970
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Re: 300 in a f-250 any good?

Post #2 by tnab1970 » Fri Jan 12, 2018 9:42 am

we have one in a 1969 f250 4x4 HI-Boy. with a pretty nice build. We are very happy with the outcome , fun to drive pulls good etc. However, naturally aspirated, this combo does have its limits. Our combo is 4.10 gears, 35" tires , 5 speed, carb. motor. I can give info on the engine build if you like. I think my sons original MPG were a little high. ( can see in thread link ) We have a second build for another sons truck F150 4x4, also with 300, 3.55 gears, 5 speed, EFI. This one is getting 13.75-15 MPG . A similar question was asked a little while back. Here is the link to the question.
viewtopic.php?f=2&t=77411

Lazy JW
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Re: 300 in a f-250 any good?

Post #3 by Lazy JW » Fri Jan 12, 2018 9:48 am

Dashman wrote:...Would I be able to get 18 mpg doing 65 mph?...


Only in your dreams :evil:
"The White OX" 1974 F-350 300-6, Stock single exhaust, Carter YF, T-18A, Dana70 w/4.11, Flatbed dually w/dump bed. "Where no oxen are, the crib is clean, but much increase is by the strength of the ox" (Proverbs 14:4)
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arse_sidewards
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Re: 300 in a f-250 any good?

Post #4 by arse_sidewards » Fri Jan 12, 2018 11:20 am

Dashman wrote:Hi everyone, new here and looking to get some advice. So how would a 300 perform in a 1973 f-250 4x4 with 3.54 gears? Would I be able to get 18 mpg doing 65 mph?could I pull 5-8000 lbs comfortably doing 60 mph?
if not how could I achieve this?

Cheers, Ty


18mpg is a reasonable instantaneous mpg for highway cruising in non-mountainous places. With traffic hills and around town driving your tank average will probably be 12-15 depending on details. Obviously these are empty numbers

You will be able to pull 5k-8k on flat ground at 60 but it won't be all that quick to get up to speed. I would be very pleased with double digit mpg towing 5k.

With trailer brakes and working truck brakes it will stop fine for what it is.

I'm assuming you have a granny 4spd and ~31-32 tires. If those are not true then your expectations are wholly unrealistic.

If you expect it to perform like a new truck with double the power then you'll be disappointed.
1994 F150 4x4 8ft, engine is basically stock.

66" leafs, extended radius arms, lockers in both ends, nothing special.

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Re: 300 in a f-250 any good?

Post #5 by Lazy JW » Fri Jan 12, 2018 12:49 pm

I drove my 81 F-150 to work for three years and tallied just over 60,000 miles in that time. I wrote down every drop of gas and every mile, year around including any and all idling, stopped in traffic (not much of that) etc. This is a 2 wheel drive with 2.75 gears and a T-18 granny tranny. I typically drive like the grandpa that I am, and I averaged just over 19 MPG for that entire 60,000 miles. This is not a one-time fillup on a good day, this is a bona-fide average for three years running in northern Idaho, winter, spring, summer and fall.

I challenge anyone to document their mileage for an equivalent period. I am confident that my mileage can be beat, but it won't be with any gasoline fueled F-250 4x4 with 3.50 gears running 65 mph.

I do truly wish it could be done, but these rigs have the aerodynamics of a chicken house and it takes a certain amount of energy to push them through the air. It doesn't matter much if is being pushed by a 300 six or a 460, the power requirement is still the same.
"The White OX" 1974 F-350 300-6, Stock single exhaust, Carter YF, T-18A, Dana70 w/4.11, Flatbed dually w/dump bed. "Where no oxen are, the crib is clean, but much increase is by the strength of the ox" (Proverbs 14:4)
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Re: 300 in a f-250 any good?

Post #6 by Harte3 » Fri Jan 12, 2018 1:24 pm

"It doesn't matter much if is being pushed by a 300 six or a 460, the power requirement is still the same."

THIS!
'83 F150 300, 0.030 over, Offy DP, Holley 4160/1848-1 465 cfm, Comp Cam 260H. P/P head, EFI exhaust manifolds, Walker Y Pipe, Super Cat, Turbo muffler, Recurved DSII, Mallory HyFire 6a, ACCEL Super Stock Coil, Taylor 8mm Wires, EFI plugs.

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Re: 300 in a f-250 any good?

Post #7 by Lazy JW » Fri Jan 12, 2018 3:23 pm

Please don't get me wrong here, I love the idea of a 300 six in an F-250 Highboy. It's just that I have put a good many miles on these engines, running heavy and light, and I have no illusions about what they are capable of doing.

My White Ox currently has the TorqueMotor 300 six in it that I built specifically to enhance the low-end grunt at the expense of high-speed horsepower; it perform exactly like I want it to, but it definitely runs out of breath at 3000 rpm, and 20,000 lbs CGVW is about 55 mph on level ground. Not many folks are satisfied with that nowadays.

My wife recently inherited her Father's 1970 F-250 4x4 Highboy snowplow pickup, complete with an oil-slobberin' 360 and a massive exhaust leak. I see a 300 six in its future... :D
"The White OX" 1974 F-350 300-6, Stock single exhaust, Carter YF, T-18A, Dana70 w/4.11, Flatbed dually w/dump bed. "Where no oxen are, the crib is clean, but much increase is by the strength of the ox" (Proverbs 14:4)
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pmuller9
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Re: 300 in a f-250 any good?

Post #8 by pmuller9 » Fri Jan 12, 2018 3:27 pm

I'm going to play the other side.

I do truly wish it could be done, but these rigs have the aerodynamics of a chicken house and it takes a certain amount of energy to push them through the air. It doesn't matter much if is being pushed by a 300 six or a 460, the power requirement is still the same.


This is true but it doesn't take into account engine efficiency or the ability to extract more energy from the same amount of fuel.
If you're talking about just dropping in a stock carbureted 300 then 18 MPG is not going to happen as previously mentioned.

For example my heavier 2001 Crew cab 4x4 automatic gets 18mpg at 65 with a 5.4 V8
So I'm not sure what a later model 4.9 EFI would do in a 1973 f-250 4x4 with 3.54 gears?
I'm assuming it's not a high boy

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Re: 300 in a f-250 any good?

Post #9 by arse_sidewards » Fri Jan 12, 2018 3:35 pm

pmuller9 wrote:I'm going to play the other side.

I do truly wish it could be done, but these rigs have the aerodynamics of a chicken house and it takes a certain amount of energy to push them through the air. It doesn't matter much if is being pushed by a 300 six or a 460, the power requirement is still the same.


This is true but it doesn't take into account engine efficiency or the ability to extract more energy from the same amount of fuel.
If you're talking about just dropping in a stock carbureted 300 then 18 MPG is not going to happen as previously mentioned.

For example my heavier 2001 Crew cab 4x4 gets 18mpg at 65 with a 5.4 V8
So I'm not sure what a later model 4.9 EFI would do in a 1973 f-250 4x4 with 3.54 gears?


I can repeatably get 20-21ish on highway only drives with my '94 with 31s 3.08s an an E4OD. I think 18mpg from a carb'd 70s brick is doable. He'll be at a more efficient operating RPM and have a lot less parasitic loss from the transmission but aerodynamics will work against him.
1994 F150 4x4 8ft, engine is basically stock.

66" leafs, extended radius arms, lockers in both ends, nothing special.

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Re: 300 in a f-250 any good?

Post #10 by Lazy JW » Fri Jan 12, 2018 5:56 pm

Yup. Show me 60,000 miles of continuous data and I'm all ears :D
"The White OX" 1974 F-350 300-6, Stock single exhaust, Carter YF, T-18A, Dana70 w/4.11, Flatbed dually w/dump bed. "Where no oxen are, the crib is clean, but much increase is by the strength of the ox" (Proverbs 14:4)
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Re: 300 in a f-250 any good?

Post #11 by Wesman07 » Fri Jan 12, 2018 7:42 pm

I can just about touch 15mpg if I'm running all highway. That is at 60-65mph with 12.5" wide tires, 5,000lbs empty, 2500 rpm and my truck sits about as tall as a new super duty.

I think the answer is yes, but at what expense?

The difference between 55 to 65 mph is very noticeable at the pump. But doing 55 on the highways around Philadelphia is down right dangerous. It's all give and take.

If you want good fuel mileage:
Keep your vehical light
Keep it low with skinny tires
Focus on gearing!
In-lines we trust

86 f150 300 efi with advanced stock cam. Np435, Dana 60/ 10.25, 35" BFG's, four link front suspension with 12" travel fox coil overs, custom deaver leaf pack in the rear.

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Re: 300 in a f-250 any good?

Post #12 by Dashman » Fri Jan 12, 2018 10:50 pm

so will the 3.54 gears and 4 spd let me pull more weight at higher speeds? I got a f-150 4spd 300 with 3.73, it's amazing what it can pull, but on the highway it struggles especially after 55mpg (like falling off a cliff). At 70 mph I do believe my motor should be reving around 2500-2700 rpm keeping it in the power band more. Will this help?

Thanks for the replays, ty

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Motorboy
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Re: 300 in a f-250 any good?

Post #13 by Motorboy » Sat Jan 13, 2018 7:05 am

Dashman wrote:Hi everyone, new here and looking to get some advice. So how would a 300 perform in a 1973 f-250 4x4 with 3.54 gears? Would I be able to get 18 mpg doing 65 mph?could I pull 5-8000 lbs comfortably doing 60 mph?
if not how could I achieve this?

Cheers, Ty


I hate to say this but I think what you are asking out of a 40+ year old truck isn't entirely realistic. I have 2 f250's with 300's in them both run 4.10 gears and have 32'' tires. My'89 rwd has a c6 and efi, my '80 4x4 has a 4spd w/ granny gear and a single barrel yfa. I love both trucks and they have proven to be great workhorses around our farm. I have never been overly concerned about my mileage as most of my driving is on back roads and through small towns under 45mph. I would say in these conditions both trucks about 15-18mpg depending on if i'm hauling something or empty. The times I've hauled or towed on the highway going 55+ i notice they get awful thirsty. The advantages of these trucks are they are cheep to insure, easy to maintain and DIY repair, and the pride of owning an older vehicle.

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Re: 300 in a f-250 any good?

Post #14 by 86f250straight6 » Sat Jan 13, 2018 4:56 pm

I think the truck is too heavy for what youre expecting, With OD cruising flat @55 I estimated between 16-18mpg, add a hill in the mix and its like dumping 5 gallons of gas downthe carburetor lol. I think a set of 4.10 gears with no more than a 33" tire will help get the weight moving without flooring it everywhere. In my experience, half the battle of getting good mpg is driving style. With a little more gear you donthave to work so hard to getup to speed, and a few more rpm at cruise sppeed means you can hold your speed without downshifting or flooringit.
I'm trying to build a truck that I can't break :bang:

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Re: 300 in a f-250 any good?

Post #15 by Lazy JW » Mon Jan 15, 2018 8:22 am

Motorboy wrote:... The times I've hauled or towed on the highway going 55+ i notice they get awful thirsty. The advantages of these trucks are they are cheep to insure, easy to maintain and DIY repair...


^^^This. If you really feel the need to pull heavy loads at high speeds, get a diesel. The Fordsix engines were designed for folks like me who want simple, reliable engines that can get-er done without breaking things too often.
"The White OX" 1974 F-350 300-6, Stock single exhaust, Carter YF, T-18A, Dana70 w/4.11, Flatbed dually w/dump bed. "Where no oxen are, the crib is clean, but much increase is by the strength of the ox" (Proverbs 14:4)
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Re: 300 in a f-250 any good?

Post #16 by guhfluh » Tue Jan 16, 2018 6:49 pm

All F250 from 67-77.5 4x4 are "highboy" trucks with a divorced case. A few years before 67 could be considered the same as well.

I'd say it's possible, just not plausible. I can get close to 20mpg at 65mph if I try, but add in anything other than that constant 65mph on flat ground and it'll drop fast. That's with overdrive and 3.73s on 28"ish tires. You didn't mention what transmission or tire size, but unless they're small and skinny tires and/or an overdrive, 18mpg instant at 65mph will probably only be a dream. You'll have to meticulously go through every part of the truck and make sure everything is at its best and geared towards max efficiency to be able to get there.

I'm sure if outfitted correctly, it'll tow 8k fine. Steering and brakes is what I'd concern with, but "comfortable" is subjective.
1967 F-250 Crew Cab 2wd, 300 6cyl, T-170/RTS/TOD 4-speed overdrive
240 head, Offy C, EFI exhaust manifolds, Comp 268H, mandrel 2.5-3" exhaust, Edelbrock 500, Pertronix ignitor and coil, recurved dizzy. 200whp/300wtq

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