I have a lead on a GMC pick up with a 270 straight six. I want some opinions on that motor. I have mid 80's axles for a 4x4 (corporate 10 bolts) with an Np208 transfer case). I want to put on the truck and possibly use a 5 speed tranny with that combo. It will be a daily driver. Will it be able to get out of its own way or should I just swap in a 305? I want gas mileage and decent power but I don't need to haul ass. I will be putting a flat bed on it and using it as a work truck. I know it's not traditional but I want this as my daily. Thanks in advance for the info.
The 270 makes lots of torque, it was originally a work truck engine afterall. The GMC sixes are not known for great gas mileage but it would be cool to run one. What 305 are you talking about, the GMC V6 or the Chevy small block?
I had a 270 in my '32 Five window, and then later in my Vega before finialy putting it in a friends streamliner. 32=158 mph Vega=177mph 'liner=202mph Thing lasted for years. Never did kill it. Sold it as a runner. I think they are pretty good motors
I had the 305 Chevy in my '56 shortbed, it was built a little stronger than stock and moved the truck fine with its highway gears. Probably got around 15 mpg around town but it was only intended to be a light duty daily driver. I think with the torque of the 270 you'd be happy with it in a work truck. I have no clue as to the gas mileage comparison.
There's a tech article on putting a T-5 in a '41-'46 GM truck on stovebolt.com: http://www.stovebolt.com/techtips/tranny/sandoval/index.html It's in a '46 Chevy truck, but the process in a GMC should be the same. I saw a '46 GMC at Goodguys here in town that had narrowed '83 blazer front and rear differentials under it, mounted on the stock '46 front and rear leaf springs.
The big 6's build so much torque at such slow RPM your only concern will be getting enough gearing behind it so's it'll be in its working range at todays road speeds. I put a 292" six in my daily driver '55 Bel Air & with a manual O.D. & 3.08 axle. After about 50K. miles I can say I'm very happy with it. A 270 should work great.
Thank you for all the info. I figure if I can get the truck....guy won't return my call.... I am into the T-5 idea(thanks wayfarer) and My guess was a low 3's rear end( thanks inline 292). Anyone ever do the 4x4 conversion to the t5 with an NP208? Also does anyone have a good source for these motor parts? Does the Fenton stuff fit? Also I think I may be ok with the axle width with what I have. Maybe just have to play with rim back spacing. Anyone ever do anything like this before? Thanks again
I have a 270 which I drove tonight. It easily moves my Suburban down the highway at speed, I would not be afraid of running one in your truck.
I've got one in my 58 truck now. I haven't gotten it running because I'm on other stuff right now. Had been turning over the idea of dropping a 350 Pontiac with a TH400 or 350 in instead. Good news on the 270 as I haven't found tons of info on it and no luck with parts.
Forget the T5 to 208 idea, if you're gonna do that it's way cheaper to get a divorced tfer case and do it with totally seperate components. Plus the T5 will scatter under any 4x4 abuse at all. If you're working it, at some point it will require abuse. Flatbed, working, fullsize 4x4, with a sixer or 305 huh? You must really like that slow lane. Don't expect to top 15mpg with either a sixer or a 305, they'll be worked so hard that they get sh*tty mileage. (in addition to the 4x4, most flatbeds are 2x-3x the weight of a regular box). Regular ole 350 will probably get the same mileage as a sixer or 305 because it won't work so hard. Going to a 454 is usually only a 2-3mpg penalty and expands the truck's hauling ability significantly. It's a quirk of big heavy trucks. Honestly if you wanna worker truck and have MPG concerns, early fuel injection chevy 4x4s are about giveaway priced and beat old trucks by 3-5mpg across the board. Start there for either your complete truck or complete engine/trans/transfer case. They made those with truck 5 speeds that'll survive a 4x4 clutch dump but the tfer spits out on the wrong side for a chevy straight axle frontend. But either ford or dodge used a straight axle that is on the correct side. good luck
With what Shifty said it does make a point. As far as a motor tranny tfer case combo what would be the best? I have the axles, transfer case 350 auto which I want to get rid of and do a 5 speed. I am not going to be hauling much. Just stuff for my side job handyman business but I need to get the best mileage I can because where I live nothing is close. I am open to ant ideas to get me where I want to be. Decent mileage (especially highway), 4x4, midrange hauling power and hopefully bullet proof. What are your thoughts.....Anyone have something for sale like this or run anything close to what I'm looking for?
Decent mileage in a full size 4x4 is relative. What do you consider decent? What are the gears in these axles you have? What size tires do you intend to run? Shifty is right that late 80's early 90's EFI trucks are cheap these days. My own experience is that the difference between big block and small block is more than 3 mpg, having owned both. Using an EFI small block and an overdrive transmission I still would not be optimistic you'd ever break 18 mpg with what you describe. If fuel mileage is king you may need to consider Diesel.
I think you can have any 3 of those 4. The diesel idea isn't a bad one depending on miles and budget. good luck with the project, and the business
Thanks for the info. My plan now if roughly formed around a 350 with a 5 speed. I think that will get me close to where I need to be. Had a 1993 GMC with a 350 and 5 speed that treated me good. I would love a diesel but it is cost prohibitive unless it is in something already for a deal. Just for kicks. On that note (diesel) what is your recommendation? I found a 56 Chevy 4x4 on craigslist with a 350 with a 4 speed with granny with highway gears. A bit more than I wanted to spend but more complete and my time is tight. In the Los Angeles section. Thanks again to Shifty and Sub for the opinions. It is greatly appreciated.
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