Well, I've decided to get a 3:55 geared rearend. Hopefully I'll get lucky and get around 12-14 MPG towing my Mustang.

 

When I moved from Reno to Billings Mt, I was towing my 72 Pontiac Ventura II. I went 1052 miles, up some nasty mountains, and I got pretty decent mileage. My truck handled it really well, but I used 4 quarts of oil and I spent about $250 in gas. That was with the Holley 4180 and 4.10 gears.
I'm moving back in 9 days towing the same car but this time I have an Edelbrock 1406 carb and no smog crap, the same 4.10 gears though. If I could do it all over again, I'd go with 3.55's or 3.73's.

 

Well, I dont know how much the gas was at the time you made your last move, so I have no way of gauging the mileage. However, guestimating that your last move was at least 3 years ago and fuel prices ranged from around $1.39 to $2.39 per gallon, I have guessed that you used around 175 to 200 gallons of fuel. That said, your mileage really wasnt all that good around 7 MPG at best given a distance of 1052 miles. I'm most likely wrong about the actual gallons used though, so please forgive me in advance.

 

Yeah, I guess that that kind of info would be good to have.
Anyway, I moved to Billings 8 months ago, and gas was around $2 a gallon.
Considering all the weight I had in the back of the truck with the car, extra 12 bolt GM rearend, spare parts, and such, I think it was OK. I would still go with the 3.55 gears if you want mileage, but when I was going up the Rocky Mountains, I averaged 65 MPH up some nasty grades. You sacrifice mileage for grunt with the 4.10's.

 

I have a 80 full size Bronco 4x4 with 460 bored .030 and 4v Edelbrock 600cfm. I use it to pull a car tailer over the Cascades in Oregon, get 10-11mpg when towing.

 

bertha66, What rearend gears do you have in the bronco?

Big Hoss, Your mileage was around 8.4 MPG. Thats not what I'm looking for. I have a 67 mustang with 4:11 rear gears, and that thing sings to me at around 55-60 MPH. It revs around 3200 RPM, and thats way too high for my comfort. I would prefer the motor(especially in a big block) to be around 2200-2400 RPM while cruising at around 65 MPH. With a 460, I should have more than enough grunt to give up some on the hills in trade for some mileage. Now, I made a move to Ohio from Washington State a few years back with my 67 mustang. I used it to tow a dual axel Uhaul trailer with all my stuff. It didnt labor up any of the passes or anywhere else for that matter. At that time, my mustang had 3:00 gears and a 302 motor. Of course, at that time, fuel was MUCH cheaper, and so I wasnt as concerned about mileage. When I moved back, I had a crewcab 1 ton GMC dually and towed my mustang back while hauling everything else I had in the bed of the truck. I got around 14-16 MPG with that truck. It had a 454 in it, but I ahve no idea about the rear gears. I DO know it had NO problems with ANY hills, passes, or grades at all. Once I get the motor into the truck and get the gears in it, I'll put up a post to let everyone know the results.

 

My 84 F250 stock 460 regular cab long bed 2wd with a swapped in ZF 5 speed and 4.10 rear end gears in a dana 70 rear axle runs at 2100 RPMS at 65 and gets about 12 to 15 mpg doing so on the highway being empty i was gonna have my rear end gears swapped but then decided to get a ZF 5 speed instead the best mod ever for my truck i still have my 4.10's and have all the get up n go i need but also now have an OD gear ZF5 speed swap recomended! hey big hoss 29 you back in reno now? i live real close to there i go there often ever heard of or been to Loyalton, CA? lol how you like that reno traffic? i do lots of that with other drivers

 

I was born and raised in Reno and I moved to Billings about 7 months ago. I thought I hated it in Reno, but I realized that Reno is home. So in 6 days, I'll be back there with the traffic as well. I've been to Loyalton, Portola, Quincy since I was knee high to a grasshopper. I love the fishing in the feather River.

 

Yeah lol i went there today I had to go to pic n pull look for some parts with a friend I used to work in Quincy last year and part of this year at the US Forest Service I like the area Quincy is in but cant stand the town you know hoow you ripped allt he smog stuff off your truck do you have to put that back on since in reno/sparks you have to smog them every year or can you get around all that?

 

Ohhh, I have ways around the smog laws. I have a friend that does smogs and he can do that for me. I'm not worried about it passing because it runs cleaner without the smog crap, it's the visual I might worry about, but, the truck is non-catalyst anyway. So Washoe County might give me some slack.

 

1977 F150 2wd mildly built 472 BB 3:50 gears with 2500 stall convertor C-6 auto about 8mpg on a good day
My other rig 1977 F-250 408 with RV cam, headers, 4 barrel, 3:31 gears, T-18 4 speed and it gets 12 or better.

 

You guys are killing me.

I have a 77 F150 swb 4X4 with 460 bored 30 over with KB flat tops with 1 valve relive, eagle rods, a comp cam with .574/.580 lift and 234/244 @50 duration inside a c9ve block topped off with c9ve heads fully ported on exhast side and super cobra jet valves, complemented slitghy by 1 7/8 hooker super comp headers. Feuled by a edelbrock intake and a Dominator 1050.

I mud drag and we run 150 ft., my gears are 4.56 and a Borg Warner transfer with a 2.72 reduction making my gear ratio a 12.40.

I can make aprox. 10 passes on 6 gallons of 110 octain fuel. That is 6 gallons for every 1500 ft.

Can anybody figure my fuel milage for me?

I think it must be a little below what you guys are getting

Just having fun.

 

You will never get 12-14 mpg towing that car with 3:55's or with any ratio. You might be able to get that empty on flat land going 55-65. The only way I ever got my stock carburated 460 to get 14 was with a 2:70 gear and cruising at 55 with cruise control on. You will be much happier with 4:10's going through the mountians, but you are going to get single digit econ #'s regardless of what combo you have. The key is to watch a vacumm gauge hooked up inside the truck. With a higher gear it is harder to keep the needle at a higher reading when towing. i.e. higher gears load the engine more than lower gears. Good luck

 

We will see...that sounds like a challenge to me. I am always up for a good challenge.....Peace

 

my F-600 with 6:17 gears and a 5-sp, I seem to get 10-12 mpg (empty)

looking at replacing the gears with 4:88s


it only goes about 70 though...