Register now to get rid of these ads!

350 not shifting

Discussion in 'The Hokey Ass Message Board' started by wayfarer, Aug 21, 2013.

  1. wayfarer
    Joined: Oct 17, 2003
    Posts: 1,790


    Ok, since I'm at my wit's end, I thought I'd ask for some advice. I have a 350 tranny behind a small block in my '53 Chevy wagon. I just got the car on the road and it's not shifting like it should. I can get it to shift out of first, but I have to rev it in order to get it to work. Everything I've read says it's the vacuum signal that shifts the transmission. So far I've replaced the vacuum modulator, replaced the vacuum line (hardline with VERY short pieces of rubber hose on each end), and backed the adustment on the modulator all the way out. It's better than it was at first, but still doesn't shift anywhere near when it should. The transmission is a fresh rebuild. What am I missing?
  2. Pull the governor cover (rear left, held on with clip), pull the governor, and replace the gear that is attached to it.

  3. I think the modulator valve screw should be run in some (to firm up the shift) but I may be wrong. Is the fluid level normal?

    Posted using the Full Custom H.A.M.B. App!
  4. Make sure the vacuum source is correct. FULL vacuum at idle. If you have it on "ported" vacuum (low or no vacuum at idle for vacuum advance) it won't shift right

  5. wayfarer
    Joined: Oct 17, 2003
    Posts: 1,790


    It's got full vacuum, drivers side port on Edelbrock carb.
  6. Not questioning your ability but are you sure you have enough fluid in the transmission? HRP
  7. 47chevycoupe
    Joined: Dec 25, 2007
    Posts: 527


    Has a shift kit been installed? If not its probably the governor. There is a valve inside the governor that could be sticking also.
    Last edited: Aug 21, 2013
  8. X2 on checking the governor gear
  9. I was thinking the same thing. The trans takes at least 12 quarts. A bit more if you have an additional trans cooler.
  10. wayfarer
    Joined: Oct 17, 2003
    Posts: 1,790


    Tranny's full; no shift kit.
  11. gimpyshotrods
    Joined: May 20, 2009
    Posts: 18,002


    And remember to check it hot, while running.
  12. George/Maine
    Joined: Jan 6, 2011
    Posts: 949


    If its stuck in passing gear it wouldn't shift. check lever on trans.
  13. d2_willys
    Joined: Sep 8, 2007
    Posts: 4,149

    from Kansas

    2nd gear accumulator piston or band. How is reverse? If it slips then the pump pressure may be low.
  14. Do you have a full range of gears,does the car move in 1,2 and drive? HRP
  15. Could be something as small as a pinhole in the vacuum tube to the modulator. My buddy's van had the same problem, turned out to be a dry-rotted cracked hose.
  16. VoodooTwin
    Joined: Jul 13, 2011
    Posts: 3,455

    from Noo Yawk

    Had the same issue today in mine. Turned out to be low fluid level. Check it over and over, sometimes the fluid level doesn't read properly on the stick.
  17. Or check kickdown cable @ the carb in case it's hung up
  18. potshot
    Joined: Jul 15, 2005
    Posts: 68

    from MT

    There are 3 things that can cause a no upshift:
    no governor pressure, stuck valve or stripped gear
    low vacuum, make sure you have 15" of vacuum AT the modulator at idle
    stuck kickdown cable
  19. rfraze
    Joined: May 23, 2012
    Posts: 2,003


    x2 on the kickdown cable. Did not see it mentioned. How do you have it adjusted?
  20. wayfarer
    Joined: Oct 17, 2003
    Posts: 1,790


    Kickdown cable is fine, it is tight at WOT and loose at idle. I have a Lokar flexible dipstick, maybe it's not reading right. How much fluid should a 350 hold? 9-10 Qts. including converter?
  21. Engine man
    Joined: Jan 30, 2011
    Posts: 3,476

    Engine man
    from Wisconsin

    How deep into the transmission does the dipstick tube go? I've found a couple that someone forgot to install the tube with the transmission and cut some of it off to get it in after installation. Without the tube inside the transmission, fluid can be sprayed onto the stick making the level look higher than it actually is. With the stick removed and wiped clean, have a helper run the engine in neutral and shut it off. As soon as the engine stops, put the dip stick in and check the level.
  22. 12 Quarts with the torque converter,,as for the Lokar flexible what I did with mine,,throw it away! HRP
  23. THIS! They're pure garbage
  24. brad chevy
    Joined: Nov 22, 2009
    Posts: 2,627

    brad chevy

    You said its a fresh rebuild,why not take it to whoever rebuilt it and let them check it.
  25. Any updates? HRP
  26. 327Eric
    Joined: May 9, 2008
    Posts: 1,528

    from Diablo Ca.

    Pull your vacuum line off the carb, and put it onto a dedicated port/tee on the intake manifold itself.
    Last edited: Aug 22, 2013
  27. burl
    Joined: Nov 28, 2007
    Posts: 739

    from Minnesota

    That's what I was thinking.Didnt think there was enough vacuum off the carb to make it work right.
  28. George/Maine
    Joined: Jan 6, 2011
    Posts: 949


    Try removing the kick down you really don't need it make sure it has spring tension.
  29. elba
    Joined: Feb 9, 2013
    Posts: 624


    If your modulator is adjustable, back the screw " out " to make an earlier shift, " in ", to make a later shift.
  30. wayfarer
    Joined: Oct 17, 2003
    Posts: 1,790


    I added fluid and adjusted the modulator (I had it backed all the way out and it still wouldn't shift). I pulled the governor and it seems fine, but I do have another one.

    The governor:

    I don't know if it's worth pulling it apart again if this one looks fine. I have the vacuum hooked to the driver's side port on the edelbrock carb. It's supposed to be full manifold vacuum.

    It's a fresh rebuild, but I've been building the car for eight years and the guy who rebuilt it is now dead; I can't really take it to him.

    I can get it to shift, but it's still shifting really late. I tried disconnecting the kickdown cable, still not a difference. What should be my next course of action?

Share This Page

Register now to get rid of these ads!


Copyright © 1995-2021 The Jalopy Journal: Steal our stuff, we'll kick your teeth in. Terms of Service. Privacy Policy.

Atomic Industry
Forum software by XenForo™ ©2010-2014 XenForo Ltd.