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Motor conversion question

Discussion in '40- & 55-Series Tech' started by nspctr1, Aug 28, 2006.

  1. nspctr1

    nspctr1

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    For those of you who dropped the stock engine and installed a 350 or other larger engine, did you swap axles also or are you running stock running gear? I have a 283 in my 73 with stock drive train and it will move on the low end but it still sounds like it's gonna blow up running 65 down the interstate. Should I change the axles or what? It's never gonna be a rock crawler and will probably see very limited off road use except just to go fishing, dove hunting etc.

    Kevin
     
  2. Poser

    Poser Oh...Durka Durka Durka. s-Moderator Supporting Vendor

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    What size tires are you running..... Stock H78-15's? ;)


    You can install larger diameter tires or instal 3.70 gears front and rear....or just run it and realize that a small block, just like a Land Cruiser six can run at 3500 all day long without issue...



    :beer:
     
  3. bandy rooster

    bandy rooster

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    I run stock axles in my 71 fj40 but i don't have the coarse spline birfs and i also have 4 wheel disc brakes... I run an Sm465 but i chose this to use this because of the low 1st gear. If i were just gonna put around town and never wheel i would have went with a 4 spd landcruiser trannsmission and t-case.. although i don't know which trannys are avail. for the 283
     
  4. nspctr1

    nspctr1

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    I'm running BFG's 31" tires, I guess I can hook a tach up and see what the rpms are at 65 mph but it sure sounds like its around 5K...
     
  5. Rice

    Rice SILVER Star

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    X2. Not a lot more to add. Could move to OD transmission but the cost per benefit is minimal. Some 33's will make some difference. You be the judge:

    31's at 60 MPH puts you just under 2700 RPM
    33's at 60 MPH puts revs at 2500.

    Rice
     
  6. nspctr1

    nspctr1

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    Really !! It sure sounds like its kicking about 5K RPM's. Maybe it's just road noise....
    Thanks
     
  7. numtel

    numtel

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    I've got 34s and I'm doing about 2800 rpm at 60 with a 350 and it makes a bunch of noise but I never have any problems with it. Overdrive would be nice but not necessary.
     
  8. Rice

    Rice SILVER Star

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    It sounds very much like you're running 4.88 rears. Should be turning a little over 2400 if with stock rear ends.

    Kevin, the feeling of turning lots of RPM's at highway speeds is very possible. Could be time for a tach if you're still not sure.
     
  9. numtel

    numtel

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    I've got a th350 and when I let off it goes down to about there. Stupid slushbox sucks my power.:crybaby:
     
  10. Brian in Oregon

    Brian in Oregon

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    As you've probably seen from my posts, I'm running a 350. My gears are 4.10, and tires are 33". I'm turning a bit over 3000 rpm at 65 mph. It's not the engine that sounds like it's at its limit, it's the geartrain. I haven't felt like pushing it to 70 mph.
     
  11. Jetboy

    Jetboy

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    Do you feel that it is the tranny that is at it's limit for speed? I used to run my mini at 75-80mph on a regular basis with 35's and 5.29 gears. It seemed to do just fine, so long as the power didn't run out. My 40 hasn't seen that much speed. Seems like 65 is about all I want to push it too for extended periods. I'm planning a conversion to either a 4.3 or 5.3 vortec in the next couple years, but I have been contemplating going with a mini v6 5speed tranny and dual mini cases with a centered rear end. Seems like the cheapest way to get into a 5 speed and with the lower gearing options it might hold up reasonably well. Probably a 4.3 so I can push it as far foreward as possible. What do you all think?
     
  12. phobos0001

    phobos0001

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    same story here, stock everything with a 351 clevo on the stock tyres, sits at around 2800ish at 100km\h and does it all day long, mabey put a bigger radiator in to keep the block cool but i wouldnt worry, a bit of revvs never hurt a motor....too much:D
     
  13. Brian in Oregon

    Brian in Oregon

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    I have no clue if the running gear is at its limit or not. Thegear noise combined with the steering wander and the braking wander makes me uncomfortable pushing it beyond 65. Fuel economy really plummets between 55 and 65 as well. The FJ40 is not exactly streamlined.

    If I were doing the Mark's of Australia conversion from scratch, I would have opted for an Aussie 5-speed transmission. That would have given the equivalent of 3.50 gears when in 5th (if you have 4.10 gears). But for that kind of money, in the long run, it might have been better to put in a totally different transmission.