New here, just bought a 1977 M880, so of course.......

OK, I traded for this truck because it's a 2500 lb load carrying truck, and I have to haul my drinking water in, as I have no well. I gather it's a rather basic M880, 1977 with a 318 and automatic tranny. I have a 325gal tank to put in the bed. For now, that's about all it will be doing. However, this truck might become quite a toy for 4 wheeling, hunting and fishing, etc. My questions/problems ( so far) are listed below as I need some help. I had no idea what I was getting into with this truck. I''m not much of a mechanic, but my stepson loves to tinker, so between us we can do most of the work. I don't care if I get it back to stock military, but with a great workhorse like this truck, it's a shame not to fix it to it's max potential without getting too carried away.
ELECTRICAL
I have headlights, but it looks like someone wired them directly to the dash switch and battery, bypassing wiring harness. I have no running lights, front or rear. No taillights or turn signals.Brake lights work. the fuse box appears to be a mess. The socket for the hazard flasher button is melted. Other connections on the fuse box don't appear to be correct. I read that all power to rear goes through turn signal switch, so I guess that and a new fuse box a good starting point.
TIRES
tires on it are ok for now. They are 9.5x16.5 military all terrain tires. I've already had 2 tire shops tell me to dump the rims, and go to either 16" or 17". they seem to think these rims are 'split rims' and won't even touch them for any amount of money.
ENGINE
Well, it starts right up, sounds ok for an old engine but I'd like to get the most out of it I can. It looks like I have a single barrel carb on it. Any advantages to changing it? power ? mpg increase? etc. I live 30 miles west of Colorado Springs, which puts me on the other side of Pikes Peak at an altitude of 8500 feet. I've been told that in general, unless the vehicle is run mostly above 10,000 feet, you don't have to change anything. Is this true for this truck? Do dual element spark plugs help? Split fires? Hotter or colder?Other mods, suggestions, etc appreciatedl.
I saw somewhere somebody mentioned the deeper tranny pan helps a lot. Any other ideas or comments appreciated.
OH yeah, that floor shifter, how about a quickie course on changing modes, Lo, Hi, Locs, etc.. Can I shift this while moving? My last few trucks have all had electronic 4WD, and that push button 4WD has me spoiled.
The body isn't bad, few rust spots here and there, cab floor looks relatively intact. the tailgate sucks, it's all bent up. I may just take it off and use a net, or something else.

What else should I check for now and watch for down the road? I'm a long way to having body work and paint job. Right now I just need to concentrate on mechanical stuff. And not really in a rush for that as I can make the water runs during the day only. It's only like 4 miles away on mostly back roads. I thinkk I only have to make 2 or 3 turns and I'm
there. Hence, hand turn signals can suffice for now.

Well, that'll do for now anyway. thanks in advance for bothering to answer any questions.


HAPPY NEW YEAR TO ALL!!!!!!!!!!!!

I just saw the time....
that's all folks!!!!!!!!!!!!
Myles
**************************************************
Myles Lewis
friend of Bill W. etc.
Florissant, CO (near edge of nowhere, close to the top of the world)
1977 M880
a couple or 3 civilian cars and 2 motorcycles, ONE girlfriend/partner/common law wife, 2 dogs, step son and step daughter all on some of the prettiest 2 acres of Rocky Mountain land one could ask for. Way to many hobbies to mention, and not enough time to enjoy them.

"When you live in a place that reaches 40deg below, the boilerman is real good friend to know"

Electrical:
Grounds , Groounds, Grounds. 99% of the electical issues with these trucks are related to a bad ground.

Tires:
Not split rims but about only a few tire sizes left
8.75x16.5 highway treasd , 33x12.50x 16.5, 35x12.5x16.5 & Humvee 36 & 37 inch tires.
You will need to add a leaf to the front or cut the fenders to keep the big ones from rubbing.
I went with a 16x8 wagon wheel from Summitracing.com and some 16 in Mud rovers from Tirerack on one of mine.

Floor shifter:
5 positions
Pulled back all the way towards seat _ Hi- Lock 4wd
one forward_Hi range full time 4wd
middle_neutral
next_Lo range full time 4wd
All the way forward_Lo-Lock 4wd

Shifting between Hi &Hi Lock while under 25mph same with Lo
Shifting between Hi & Lo should not be done under power


Manuals:
You can download these M880 manuals in .pdf from this site:
https://www.logsa.army.mil/pubs.htm

TM 9-2320-266-24P Parts Manual
TM 9-2320-266-34 Maintenance Manual
All can be found on Ebay on CD or in print

Engine:
150hp
Don't know about altitude adjustments

Fuel mileage improvements? Driving downhill helps


Good Luck with it

The carb is a two barrel that looks like a single from the top. If you look down in you will see two butterfly valves even though there is only one choke butterfly. You could add in a four barrel themoquad or such but economy will suffer.

The tip you got on the turn signal switch is true. and is probiably the orginal cause for all the stuff you got going on to the rear of the truck... But with all the other problems you got with the fuse block and head lights it is hard telling what ALL is wrong. one thing is for sure, unless you are an electrican the electrical problems you are having will be you biggest battle. If it has a black out light switch on the dash make sure it is in the SERVICE position.

you can still get the wireing harness for these trucks, check e-bay or local junk yard, or maybe even SATURN surplus ( I had to pay $55.00 for a NOS turn signal switch on e-bay ). in case you dont know, you can get most of the parts you need at any local auto parts store by telling them it is a 1977 W200

The drive train in these trucks are pretty reliable, I would not change the carb on it or worry about split fire plugs untill you get the lights figured out. sometimes I have a hard time shifting from the LOW ranges to HI ranges.... I have found that putting the truck in park ( and sometimes turning the engin off ) helps to shift from Hi to LOW / LOW to HI

Bob H is right about the tires.... I simply went to the junk yard and got some 16 in rims off a late 80s van and hade some p265-75-r16s put on they are the closest thing I could find to the orginal hight and width of the 16.5s

Good luck, Welcome to the forum and most importantly... POST SOME PICTURES, ( Weeeeee Like pictures )

The one I just bought has a brand new set of 9.50-16.5 Bridgestone Duellers on it, and it looks real good. My other one has 265-75-16. They are a bit taller and fill the wheelwells nice. The other choice is 235-80-16 as used on my Cummins trucks. They're tall and skinny and take lots of weight at 80 PSI

I found it is a good idea to get away from the 16,5 tires. Expensive or hard to find, or both. I went to the local four wheel drive shop. They usually have stock steel 8 lug 16" rims they have taken off somebody's truck to put fancy wheels on. I bought a set of four cheap and used them on my 880. Now tire choices are no problem.
Regards Marti

Engine:

If you want more HP without sacrificing economy, I suggest:

1.) High rise dual plane intake manifold..."Edelbrock Performer." You don't need the "Performer RPM" $230
2.) Small four barrel carb...Holley or Carter 600CFM. no bigger. The Holley 4175 series carb is great due to its small primaries and large vacuum secondaries. $300
3.) True Dual exhaust with crossover "H-pipe", full-length headers, and aftermarket hi-flo mufflers. $300
4.) Open element air filter...K&N, Summit (if you're not fording rivers or creeks.) $50

I would estimate the HP increase is about 30HP and similar torque. You'll probably get better mileage with the 4175 Holley because the primaries are smaller than the barrel diameter of the two barrel.

I forgot.

Rip out all emmissions garbage and related garbage: Air pumps, Catalytic Convertors, 10 miles of vacuum line, etc. The only vacuum lines you need go from the carb to the distributor, and from the carb to the PCV valve. If it has power brakes then there'll be a few more.

The M880's had none of these smog items installed originally.

The wiring harnesses were intentionally butchered when the BODrive lights mods were installed by the gummint in the late 70s and 80s... there were numerous plugins on both the fuse box and the connectors between the engine and pass compartments... Grounds are bad in most all trucks.. the ones with the second electrical system for radios..24 volt and two extra batteries and the extra alternator are usually really ragged electrically.. with the full time 4wd it will be hard to get good gas mileage.. Advance the timing to civvy specs and it helps some... Tranny and xfer cases... from www.saturnsurplus.com RAM

I have brand new brake master cylinders for your M880 original made in USA genuine... for $50 ea.. RAM