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thinking about swapping a 4 speed manual into my 77 with poll

should I swap to a manual for better MPG?

  • yes it should make a noticable differnce

    Votes: 2 16.7%

  • its a lot of work but will make a little differnce

    Votes: 5 41.7%

  • too much work for too little gain

    Votes: 1 8.3%

  • spend the gas money on beer and pretend to drive the truck while naked. VROOM VROOM

    Votes: 4 33.3%
  • Total voters
    12
  • Poll closed .
original balzer

original balzer

1/2 ton status
Joined
Nov 17, 2004
Posts
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Location
roosevelt utah
My 77 k20.
10eb2047.jpg


It has a 350, th350, and a 203. I LOVE this truck. I have put a lot of work into this truck. This truck gets CRAPPY feul milage. I realise its never gunna get HIGH MPG but currently it gets about 8 mpg.

Manual trans get better MPG because the power is directly conected rather spun through a fluid conection and wasted as heat.

A NP203 transfer case is HEAVY. I have a 208 that is much lighter.
So what do you guys think? Is it too much work for too little gain?
Or do you thing the MPG will go up enough to justify the swap?

I normally prefer a manual trans but it is nice so put it in gear and forget about it with a automatic.

I have everything I would need to swap it over except a 350 flywheel and a new clutch pack. I could steal the pedals, bell housing, trans and transfer case out of my red 83 parts truck.

This would also free up the 203 for a doubler for the crew cab later.

But is the 208 a bad choice for a 3/4 ton that will do some towing and off road?
 
Just to give you an idea, driving easy with a 350 rv cam and a little work/s465/208 WITH fuel injection I pull 15-17 mpg. I could probably pull more. This is on 36's with 3.73s btw.

I think changing the transfer case will make the biggest difference since you'll be part time 4wd.

I vote do it just to have a stick truck cause I love driving stick :D

Honestly in not a huge heavy heavy rig theres nothing wrong with a 208. If it was good enough for the army its good enough for me. Plus you get lower gears. Just dont put gear oil in it and you'll be fine.
 
I didnt mention the truck does have the mile marker part time kit in it so it is part time.

It just seams to me the older non over drive autos rob a lot of power. I dunno I have swapped in manual trans about 12 times on my own trucks and some friends trucks. It usualy comes from a dead transmission but this time around the trans is perfectly fine.

I prefer a manual 9 out of 10 times. But I do have my 99 yukon for when Im feeling lazy and dont want to shift HAHA.

Thinking about this got me thinking about the several trans/x-case combos I have available here and their compatability. You know for later when I want to do a doubler for the crew cab. Theres a new trhread about that because I just cant seam to find the aswers im looking for.
 
I don't think it would be worth all the work for fuel mileage. I did the same swap in a '72 and I didn't notice any change. It sounds like you have several trucks... Take all the good parts off all your trucks and put them on one truck. Sell all the rest and buy a economy car for good gas mileage. Then you don't have to worry about your wheeling machine taking you to work the next day.
 
X2 ^

If your getting 8mpg there's something else wrong. I get a solid 11 now with 35s and heavy 1 ton axles with an overdrive manual trans and lack of a tuneup. You won't gain much noticable mpg from a manual.
 
Definitely an upgrade. I did it to my 88 Suburban, my fuel mileage got better going from a TH700R4 to an SM465 and that was losing overdrive. I used a 1985 donor, so I used the NP208. It can't be that bad of a transfer case, they used them in the CUCV's. I would have used an NP205, I had a few, but using the NP208 made it more of a direct bolt in. The driveshafts even worked.

Martin
 
my 358 gets 9 mpg and its around 450 hp with a 465/205, when it had a rock stocker 350 in it the thing got 13mpg....with 465/208. the manual switch wont do much for the mpg.. what carb are you running ..? when my quadrajet was going bad i got real bad fuel mileage.
 
The 350 is built a little it is around 400-425 hp, it has a new q-jet carb.
35" tires and 411 gears.

It just seams like its always dragging something to me. I will probably go ahead with the swap just for my prefrence of a manual trans.

I have about 15-20 vehicles on any given day. Most are projects. I have a 99 yukon for a daily driver. To be honest I dont need the 77 at all if I was smart I would sell it. but the body is almost perfect and I have put a lot of work into it and just cant bring myself to part with it. Like an idiot I will continue to spend money on it. I already want to do the swap and rear disks and Im barganing on 2 more single wheel front d60s so that will end up causing more mods like crossover steering more lift shackle flip it just never ends but I love all of it lol.

I just wish I could win the lotto or something so I could quit my job and build my toys.
 
Sounds like a friend of mine. He has a '31 Ford Sedan, '31 Ford Coupe, '56 Chevy Bel Air, '71 Nova, '69 Chevy Shortbed 4x4, '71 Chevy Longbed 4x4, 3 or 4 '55-58 Chevy pickups, '35 Chevy Two Door sedan. All are projects in one way or another. :confused:
 
original balzer said:
Very easily its the oil patch. I often wonder how you guys do it out there with those low paying jobs.:haha:
Click to expand...

You mean low paying jobs and high cost of living :D You must be good at what you do because from what I have heard the oil patch is all but dried up in the Unitah Basin. I was fishing up at the Gourge last summer and it was crazy up there, we went up through Rosksprings on the way up and back through Vernal on the way back.
 
final ratio is 1 to 1 on both your th350 and 465.so it will only be a couple of mpg difference.at highway speed the auto would lock up anyway and still have the same effective ratio.i still vote manual trans tough.i like to be in charge of the shifting.
 
I'd say all things being equal you'll gain 10-12% fuel mileage over the auto...which would bring you up from 8 to 9 mpg. Getting the Q-jet tuned beteer and playing with the timing will likely net you more of a gain.

I ran a mild 355 (260HE cam) with a Q-jet, then a Holley, then an Edlebrock 1406. Had the 465/205, 3.73's and 35" MT's and regularly got 12.5-13.5 mpg on the highway.

Rene
 
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