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engine and tranny

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by ZfromNJ, Jan 29, 2002.

  1. ZfromNJ

    ZfromNJ Registered Member

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    I was wondering if I can put a mdern engine and tranny in my 74 with overdrive. due to the amount of travel that I do on the highway I think it would be beneficial if it can be done. HAs anyone done this yet and what was the cost and if there was any trouble.

    {crazy}
     
  2. 74k5inVA

    74k5inVA 1/2 ton status

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    wow! someone else is in the exact same boat as me. I to want to put a newer engine and od tranny in my 74. I have not done the swap yet and don't have all the facts yet, but i do know that project blazin' at offroad.com put a 454 and 700r4 in his. so it can be done. what kind of tranny and transfer case do you have now? i have an np203/sm465. full time 4X4 manual 4 speed with granny low. for me i am thinking of getting a tbi engine, raptor 700r4 tranny, and a part time transfer case. do a search, that is where i learned alot about trannies. in fact the raptor was new to me as of yesterday but sounds real nice. also for those of you who are answering this post, i was told that i couldn't put a 700r4 into my blazer because i don't have a computer? what about all the other oldies with the 700r4?

    If it can't be broken then I haven't had it.
    '74K5 NP203/sm465 4"Lift 35"BFGs 350ci
     
  3. dyeager535

    dyeager535 1 ton status Premium Member

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    700's don't require a computer to work. They require some input to lock the torque converter up, thats it, and even then, its not necessary, you will just be running at slightly higher RPM's in 3rd and 4th gear. Stock electrical input's are *typically* (for an early 700 equipped vehicle) coolant temp, vacuum, and Vehicle Speed Sensor to lock the converter up.

    You can run the 700 without lockup, although you generate more heat that way driving at higher MPH. (3rd or 4th gear cruising only) Everyone will tell you run an auxiallary trans cooler anyway, so no matter if you lock the converter or not, you should install one.

    You can buy aftermarket kits to lock the converter up, but they don't typically use VSS, and thats a problem. Too much lock/unlock with vacuum input alone. I'd take the setup off an early 80's 700 equipped truck if I were to retrofit, and either make the VSS fit on the speedo as it was stock, or get an inline one from one of the TPI places. You can also run a switch to lock/unlock the converter, but you have to remember to unlock it, which I know I personally would forget to do.

    I will tell you right now, I get BETTER mileage with 350/SM465/NP205/3.42/33" tires, and a slightly heavier K5, than I did with the 305/700R4/208/3.08/31" tire combo in my last K5.

    City AND freeway are better with my manual combo, and thus, I think if you were to ditch the 203, tune up the 350, and perhaps consider a gear swap (if needed) you would be in the same boat. Better or same mileage, without the weak link 700R4.

    Its a great tranny if you NEED overdrive (numerically pretty high gears like 4.10 or higher, and freeway driving) but other than that, its a semi-weak 3 speed tranny (in most stock forms) with overdrive, and a bad 1-2 gear ratio, with OD. The SM465 has pretty poorly spaced gears as well (also no torque converter) but as we've pointed out before, compare the "my 700 just crapped out" posts to "My SM465 is broke" posts, and you'll see which is more reliabel, which is more important to me than any other difference between the two trannies. I'd love OD, but realistically, it probably wouldn't help out much. The motor isn't running too many RPM's at cruise, (about 2250@60MPH) and it is at, or near, it's peak apparently, when I go to pass someone, or climb a hill. No downshifting required.

    Dorian
    My tech/links page: <a target="_blank" href=http://www.dorianyeager.com/index2.html>www.dorianyeager.com/index2.html</a>
    Why insist on counting when the ring gear has the tooth counts stamped in?
     

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