Engine revving when pushing clutch in?

Discussion in 'General IH Tech' started by TCRIMSONK, Jun 20, 2011.


  1. TCRIMSONK

    TCRIMSONK Farmall Cub

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    I'm putting the finishing touches on my first ever engine swap. It's kind of amazing, but she fired right up, as soon as I cranked long enough to get fuel to the carb!

    Now for the (potentially) bad news. Standing next to my Scout, I reach through the window, make sure it's not in gear, and turn the key. She starts up with no hesitation. (I love the sound of open headers!) After adjusting idle by ear (haven't installed the tach yet) everything sounds great. But, as soon as I climb in and push in the clutch, the engine revs up to at least twice the RPM!

    So I let the clutch back out, and the RPMs drop back to normal.

    I check again, and the transmission is definitely NOT in gear.

    Now, I haven't adjusted the clutch yet, and I'm out of the state until July, so I can't try anything yet. I'm just brainstorming with you guys, because this is so weird.

    Even with the clutch not yet adjusted, with the transmission is in neutral, what could be bogging the engine down so much???


    Background: I threw a rod in my 196 a month after buying my 1980 scout. I've spent the past 9 months swapping in a 345 from a '79. I got a flywheel and clutch for a V8, as the 4cyl setup is different. I didn't touch the transmission; it was already in my Scout, and drove fine.

    Thanks, all!
     
  2. sdhachey

    sdhachey Farmall Cub

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    check length and/or adjustment of accelerator cable (as a test, disconnect from carb). make sure engine mounts are still good and that they're tight. when pressing in the clutch, the linkage is probably moving the motor and activating the accelerator cable. and make sure there's enough play in the clutch. good luck.
     
  3. TCRIMSONK

    TCRIMSONK Farmall Cub

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    I had the same thought as you, so that's the first thing I checked.

    In the scenario above, I never have to touch the accelerator. I can start it without pumping the gas, and when I push in the clutch, it revs up immediately, without my touching the gas pedal.

    Also, I did this with no hood or air cleaner on, and from the driver's seat, watched the carb to make sure the accelerator linkage didn't move when I pushed in the clutch.

    I did replace the accelerator cable during the engine swap, so it's brand new. When I get out to look at the carb (A freshly rebuilt quadrajet) the linkage is touching the idle speed screw as intended.

    It's possible that I missed something, since I didn't have anyone around to help. I'll check this, but I think it's unlikely that the throttle is opening at any point in this scenario.
     
  4. Jay Tabor

    Jay Tabor Banned

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    disconnect throttle cable, then try.
    you didnt see the cable/throttle move any while looking/trying it, but with it disconnected that eliminates all.
    if that doesnt change things its in the trans,
    shouldnt matter at all but shift transfer case to nuetral,too and try it again.
    then with transfer case renegaged and trans in neutral grab drive shaft and see how easy it is to turn.
    only thing I can think of is somehow the countershaft bearings are bad.
    or no oil in trans.
    see when the fly wheel be rotating and clutch is engaged [ aint pushing on de pedal]
    the flywheel and disc and pressure plate, and trans input shaft and counter shaft, and all forward gears all be turning. and when you disengage the clutch[ you be pushing on de pedal] the disc should still turn.
    if you have the bellhousing cover/dust shield still off, slide under your scout, have some one depress the clutch while you watch to see how fast the disc and input shaft stop turning.
    the disc- being a small flywheel should spin merrily all by itself . .
    if it stops quickly- barely rotates once, then for sure you gots trans troubles . .

    shouldnt be the input shaft pilot bearing, shouldnt be the clutch disc/pressure plate
    unless some how some way the trans is in gear when you think its in neutral and the clutch is slipping a whole bunch, thats why you put t/c in neutral, too.
    still think its countershaft/bearings
    should be obvious noise from trans when you get to driving it.. if trans is buggered you wont be able to spin the driveshaft very easy
     
  5. Feedforward

    Feedforward Farmall Cub

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    My '72 scout does this too. The PO indicated it was a "feature". I found by looking closely at the throttle pedal linkage inside the cab just above the gas pedal, the clutch rod runs right up next to it. When I push the clutch in it forces the throttle linkage towards the back of the truck, increasing the idle. When I first started the truck up, it would idle at about 700 and hit 1000ish with the clutch pushed in. I simply loosened the throttle cable a bit at the carbeurator connection so there was a little slack in it and now when I push the clutch, the rpms rise to 800 or so. Kind of nice actually since I'm running 33" tires and need a little gas to get going in 2nd anyhow!
     
  6. Tom Mandera

    Tom Mandera Dreams of Cub Cadets

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    Feedforward has it. The throttle is adjusted "too tight" and when you push the clutch, the clutch linkage is applying a little pressure to the cable and causing the idle to jump.

    If you adjust it the other way - take the carb to WOT and the pedal to the floor, and set things there, you may not have this problem - and you won't be as likely to break the cable from flooring it. :D
     
  7. Ristin

    Ristin Binder Driver

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    My Terra did this to. I found the clutch rod had a slight bend to it that would push on the accelerator arm. I was able to twist the rod so the bend didn't hit the arm, and problem solved.
     
  8. TCRIMSONK

    TCRIMSONK Farmall Cub

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    Okay, I finally got back to the garage and you guys were right. Thanks!

    Now its just a matter of adjusting the turnbuckle clutch rod. The problem is, I can't get it to budge. I see a hex head looking bit on the bottom of the clutch rod bit that attaches to the pivoting linkage. Is that turned down to lock the rod? I can't seem to get that to turn either.

    I already broke and re-welded part of this linkage, so I don't want to force anything else and break it too.
     
  9. J.D.Oldham

    J.D.Oldham Binder Driver

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    Mine did the same thing. I saw that the clutch rod was bent, so I took it off and turned the bend away from the gas pedal. That helped but did not solve all my problems with engine R.P.M. increase. I then noticed that the gas pedal had been broken and rewelded crooked. I removed it and ground down the back of the arm to clear clutch linkage. Problem solved.:D
    I had had this problem for several years and thought my tranmission had a bad berring or something going wrong. It took my 15 year old son to see that the clutch linkage was hitting the pedal arm. :stupid:
     
  10. TCRIMSONK

    TCRIMSONK Farmall Cub

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    Turns out the hex head at the bottom of the clutch rod is a lock nut. I got it to move, and adjusted the clutch rod as far out as it would go. The problem is, the piece that's labeled 16 in this image is still 3 inches away from part 11.

    [​IMG]

    When I had the engine out, I noticed a large bolt at the top of the fork where it meets the rod from part 24. Might I need to loosen that nut enough to rotate 24, so everything can connect?

    I should mention that I've also added a 1 inch body lift. This revving problem was happening before the body lift, and I think I may have made the problem worse with the lift. I've read that I shouldn't need an extended clutch rod with just 1 inch of lift, but I'm willing to get one if that's what I need to do.

    Thanks, all.
     

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