240/6 power, or lack thereof

[stink bear]

Anyone else have a 4x4 F100 with a 240/6, NP435,and Dana 21?
I inherited one and have been fixing it up. I like the old truck (72) but it doesn't have enough power to pull a whore out of bed and it only gets 11 mpg. It must have some pretty low gears because it turns about 2800 rpm at 55 mph. I would think it should either have decent power or get decent gas mileage but I get neither. I'm wondering if the engine / drive train combination is just weak, or if the engine isn't putting out the power it should. I did a compression check and that was good, it seems to run well enough, just lacking power. Anyway, I would like to hear from anyone else with a similar truck to see if their experience is similar.
I am planning to swap the 240 for a 302, but I'm still curious about the 240.

[basketcase0302]

"stink bear"Anyone else have a 4x4 F100 with a 240/6, NP435,and Dana 21?
I inherited one and have been fixing it up. I like the old truck (72) but it doesn't have enough power to pull a whore out of bed and it only gets 11 mpg. It must have some pretty low gears because it turns about 2800 rpm at 55 mph. I would think it should either have decent power or get decent gas mileage but I get neither. I'm wondering if the engine / drive train combination is just weak, or if the engine isn't putting out the power it should. I did a compression check and that was good, it seems to run well enough, just lacking power. Anyway, I would like to hear from anyone else with a similar truck to see if their experience is similar.
I am planning to swap the 240 for a 302, but I'm still curious about the 240.

I would be willing to bet that it has 4.10 gears in the axles, (being 4 X 4) making it a pulling torque monster rather than a road warrior.
It would be real...easy to drop a SBF, (yeah...302 stroked out to a 347) or a 300 (which can be found for pretty cheap into it as a game changer.

[8ton]

Have you done a full tune up on it yet? Tired ignition components and slow timing will make a fuel hungry dog out of most any motor. If you are serious about doing the swap sooner than later, it may not be worth the cost.

[colnago]

I would be willing to bet that it has 4.10 gears in the axles, (being 4 X 4) making it a pulling torque monster rather than a road warrior.
It would be real...easy to drop a SBF, (yeah...302 stroked out to a 347) or a 300 (which can be found for pretty cheap into it as a game changer.

On my 2WD, I have 4.10 in the rear, and I turn 2500RPM at 55MPH. In fact, my speedo is whacked out, and I've learned to gauge my speed by the tach, since it's rock-solid.

Also, I'm driving with a 352. I would love to get 11MPG.

Joseph

[Jacksdad]

Also, I'm driving with a 352. I would love to get 11MPG.

Joseph

I'll second that

Have you thought about a 351W? Later model roller cam motors are easy to find. Or if you're sticking with a 302, 96-01 5.0 Explorers came with either GT40 or GT40P heads depending on the year. With the exception of the mighty Boss 302, they're the best production small block heads that Ford made.

[stink bear]

First, I apologize for not replying sooner, I didn't get email notification that there were more posts. I thought the thread died.
Thanks for the replies.
I don't recall if I've done a full tune-up but tonight I checked the timing, it was varying about 6 degrees, I think the dizzy is worn out.
I have considered a 351W. I already have a 302 out of a 77(?) truck I would like to transplant. I'm not looking for much performance, mostly driveability. With the truck having such low gearing I think a stock 302 will have plenty of power and the shorter stroke is more suited to the higher rpm's.
The torque of a 351W might be nice at times, but the truck is mostly driven on the street, the 240 pulls it around okay on level ground.
I am about to make a post about parts needed to install the 302, it came out of a truck with an automatic tranny. my truck is a manual. The post will be in the drivetrain forum.

[jzjames]

Don’t think throwing in a stock 302 is going to give you the results you’re lookin for, just my opinion.

[stink bear]

jz - I considered that I won't get the power I want out of a 302. I think it's worth a try, and if I don't get the power I want an upgrade to a 351W would be easy.
I also considered dropping a 300 in it, that would be real easy. I had a 79 F150 4x4 with a 300 many years ago. I believe it had 3.55 gears, it had plenty of low end torque but in my opinion lacked top end power.
I appreciate your 2 cents.

[jzjames]

Yes, opinions are like,...well, you know. Everyone’s got one.

I’ve had a shortbed F100 with a 302 and my current shortbed has the 300 I6. I think both had 3.70 differential.
For comparison they were both pretty much the same power-wise, maybe the 300 had an edge- (lighter).

You have a sought after 4x4 shortbed but for cruising, the 4.11 gears are not going to do it for you.
Maybe the 351W is the ticket with a different rear gears. I don’t know anything about the 351W. If it was me I’d put in a well built 300 Six, figure out the rear diff. That would be better on gas and probably fun to drive.

It’s going to be hard getting it to cruise like a modern vehicle.

[colnago]

I had a 79 F150 4x4 with a 300 many years ago. I believe it had 3.55 gears, it had plenty of low end torque but in my opinion lacked top end power.

I recently had multiple threads going about increasing the performance of my 352. The single common answer that came back was having to determine what I wanted from the engine. I decided that low-end grunt is more important to me than having a road rocket. With my C6 tranny and 4.10 rear end, I turn 3,000RPM at 65 MPH. So, the RPM range I care about is 0 - 4,000; over that, I don't care, because I will never see it.

I guess this is my long-winded way of suggesting that you decide what you want out of your truck, then decide on the engine/gearing/tires that can give that to you.

Joseph