For various reasons to complex to be worth mentioning I've decided the only truck that really suits me is a 1978 Ford F series. However with that sherman tank of a non overdrive 4 spd stick I love so much (4wd too of course) coupled with the V8's that were available at the time I'm expecting abysmal fuel economy. However I love the very long lived 300 I-6 to death and I hear even these old carbureted ones can get fairly impressive fuel economy, anyone have any first hand experience? I tried searching but anything with that info kinda got lost in the pile of crap threads that came up.
Also is the 4 spd stick behind the I-6 the same super heavy duty one behind the larger M v8's of the same year or is it something else?
How hard is it to find A/C in this year truck with an I-6? Not really critical but its nice to have when you can actually get it working.
And most importantly can this setup maintain freeway speed with a 22 foot sailboat? I need to tow one from MN to VA which is a bit of a trip.

 

I have heard of people getting 18 to 20 MPG with the 4 speed and I-6....I am pretty sure the 4 speed is the NP 435 which is as solid as they come in theses trucks and used both for the V8's as well as the I-6...if i am wrong on that someone will chime in soon i am sure.

As for Highway speeds that will depend on what your ring and pinion gearing is....I know that the 300 six is an awesome engine and has great torque but that is inherent with most inline engines.
I personally cannot advise as to how it will do towing a 22 foot sailboat but again i shall defer that to some of the guys that own trucks with the inline in them.

I do know that the 78 i had had A/C in it with the 300 six and it use to blow meat locker cold...(wish i had never sold that truck).

Anyway be patient some of the others will chime in soon with their knowledge.

 

You can certainly expect to hit the upper teens (possibly even low 20's) with a 300 IL6/4spd combo, given a highway friendly gear ratio, stock sized tires and most importantly a light right foot.

EDIT: was typing same time as Death85e

 

double post, sorry!

 

I have never even come close to 18MPG with a 300 I6. I've had several rebuilt ones and even a one year old truck with one. 3 on the tree or 4spd tranny, they all would barely break 12mpg, downhill, with the wind at it's back. The I6 hates highway speeds. Above 55mph they run out of power and suck fuel even more, quickly. That's the bad new's. The good new's, they are stump pullers! "HOG block six" as they were known. You can fry the rubber of of both rear tires if you have posi\limited slip. It will pull that sail boat all year long at 55 mpg or below with no strain. These I6's are still used in old farm trucks to pull hay\corn wagons and such. They have more power off idle than most super duty type trucks.

 

That's not been my experience, even an old tired I6 can usually muster 14-15mpg.

 

I had a new 2wd F150 I bought in 1986, 3spd with OD, as I recall I got 17-19 mpg running 65-70 mph on I-10, no cruise control and running the AC.

 

Is this info from experience? Or theoretical? Not slamming you montana, I never expierienced or heard of this high mpg with any 73-79 ford truck. Of course, I'm gonna get slammed by the dozen here that get's 16 mpg with their later FI model's etc., mayby I needed to lift my foot some

 

Well, i've owned two I6's so some is personal experience, and the rest of course, is purely anecdotal.

 

Understand. Sorry for the Hijack OP.

 

In 1986, I bought a new F150 short bed 4x4. It had the 300 six, 4spd trans and 3.08 gears. On the interstate cruising at 65 MPH, it got 16-17 MPG. I installed headers, dual exhaust, clifford intake, and a 390 CFM Holley. Even thought it had a bunch more power, it still got 16-17 MPG.

 

Marc, I travel to Bremerton a couple times a year. Let me buy you a tank of gas and lunch, I guess I'm wrong..again.lol It is only the 98th time this year. It's great to meet fellow FTE members and talk crap. The best part is to see their rides!

 

Check out his other ride.

https://www.ford-trucks.com/forums/1...barn-find.html

 

I have the same experience with my 89 f/i i6. Under 60, she will do anything I want, over 60 and I'll be back under 60 shortly pulling a load. I also have NEVER gotten better than around 14mgp and it's a 5spd.

Maybe you guys getting better mileage have 2wd's, mine is 4wd and is a heavy beast.

 

It has the potential at least to do what I want, sounds like I'll just have to buy one and see what I get then. Thanks all.