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Technical Th400 “clunk”

Discussion in 'The Hokey Ass Message Board' started by anthony myrick, Apr 26, 2021.

  1. anthony myrick
    Joined: Sep 4, 2009
    Posts: 9,999

    anthony myrick
    Member

    Nope. Same conv and trans I originally ran. But I had another th400 and conv on the engine test stand when we built the engine.
     
  2. '51 Norm
    Joined: Dec 6, 2010
    Posts: 760

    '51 Norm
    Member
    from colorado

    UH, yeah that's the critter, its been a couple of decades since that little disaster and things at that range get a little foggy sometimes.
     
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  3. Marty Vanin
    Joined: Feb 22, 2017
    Posts: 69

    Marty Vanin
    Member

    Did you measure the convertor to flex plate clearance before you went and bought spacers? The company that made the adapter doesn’t know what converter u have so they supply extra washers in case you need them. Also did you check to make sure the pilot of the converter was inside the adapter after the converter was bolted to the flex plate?
     
  4. anthony myrick
    Joined: Sep 4, 2009
    Posts: 9,999

    anthony myrick
    Member

    Hmmmm.
    I didn’t measure the space. Just spaced out the thickness of the adapter.
    The conv hub and adapter are all lined up with the crank. But I guess there is a possibility the adapter could be a tad loose.
    I guess I need to measure the conv to flywheel distance.
     
    Last edited: Apr 27, 2021
  5. anthony myrick
    Joined: Sep 4, 2009
    Posts: 9,999

    anthony myrick
    Member

    Took the converter loose.
    spacers are correct length. Discovered one starter bolt was tight but bottomed out. Added a washer and handles that.
    I still have that hollow converter noise.
     
  6. anthony myrick
    Joined: Sep 4, 2009
    Posts: 9,999

    anthony myrick
    Member

    Converter is 5/8 away from the flywheel when pushed back.
    3/8 when pushed forward and engages the hub.
     
  7. anthony myrick
    Joined: Sep 4, 2009
    Posts: 9,999

    anthony myrick
    Member

    Well poo. Cranked with the converter disconnected. Still hearing a noise. nothing shows up when using a stethoscope
    may have to pull it all back out.
     
  8. Greg Rogers
    Joined: Oct 11, 2016
    Posts: 518

    Greg Rogers
    Member

    So noise is in engine? Bummer...oh wait, noise is in trans?
     
  9. anthony myrick
    Joined: Sep 4, 2009
    Posts: 9,999

    anthony myrick
    Member

    Must be somewhere else if not the trans.
    We did a pan and pick up tube swap.
    I guess a crank touching something could be a possibility. We’re also working on pushrod length to solve the rocker arm tick.
    We’re going to tackle that then determine if we pull the engine.
     
  10. squirrel
    Joined: Sep 23, 2004
    Posts: 50,887

    squirrel
    Member

    still waiting for that video, so we can hear your clunk.

    put your hand on the engine oil pan, to see if you can feel something hitting when it "clunk"s.
     
  11. Well Grasshopper ,
    More information now,,,,,,pan and pickup tube swap as well.
    With the converter loose,,,,,it must be somewhere in engine ?
    Could the pickup be touching somewhere,,,,,,is it a screw in kind,,,,where it could swing a little and then swing back ?
    I’m not familiar with Caddy’s,,,,LoL.

    Tommy
     
  12. anthony myrick
    Joined: Sep 4, 2009
    Posts: 9,999

    anthony myrick
    Member

    rear sump pan
     
  13. anthony myrick
    Joined: Sep 4, 2009
    Posts: 9,999

    anthony myrick
    Member

    update
    installed new lifters, the Lunatti ones were .011 shorter
    the nw lifters friom the Cad Company were shaped correctly, lunatti was flat
    its seems the "clunk" ws associated with an internal issue associated with a possible bad lifter
    The noise sounded like a converter issue.
    go figure
     
    Last edited: May 14, 2021
  14. anthony myrick
    Joined: Sep 4, 2009
    Posts: 9,999

    anthony myrick
    Member

    Another update.
    I hope I don’t jinx the situation, the tap still exists. It’s kinda odd. It consistent but the tone changes. Or seems to fade. Having the rocker arm noise absent helps a lot.
    I was at the local cruise and ran the engine for a friend of mine. He had the same confused look I’ve had. This guy builds a lot of engines. It’s hard to pin point it’s origin.
    We’ve ruled out a rod noise and battled through the rocker issue.
    The guy suggested the fuel pump kinda as a joke. I’ve been all over this engine with a stethoscope and heard nothing.
    I carefully reach down to the fuel pump and can feel a tapping coming through the pump.
    My next investigation will start there
     
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  15. anthony myrick
    Joined: Sep 4, 2009
    Posts: 9,999

    anthony myrick
    Member

    Thought on an in-line electric pump
    Yea or nay.
    I’ve never used one for a carb
     
  16. rockable
    Joined: Dec 21, 2009
    Posts: 3,784

    rockable
    ALLIANCE MEMBER

    I used a Carter electric pump on my Plymouth. Install it near the tank and down low. Works great. Best of all, no cold start up problems after the fuel evaporates from the bowl. Just switch it on, wait 5 seconds and crank it up.

    I did install a regulator and adjusted it to 5 psi for my Edelbrock carb.
     
  17. anthony myrick
    Joined: Sep 4, 2009
    Posts: 9,999

    anthony myrick
    Member

    That’s what I’ve heard. The Q-jet bowls are small. I have a good spot about 3feet from the tank pick up. It’s near an access from the floor so I could service from inside if stranded
     
  18. 51504bat
    Joined: May 22, 2010
    Posts: 3,381

    51504bat
    ALLIANCE MEMBER

    If you go electric make sure to use an inertia activated fuel pump safety switch in addition to a pressure regulator.
    Pull a part from a Ranger pickup or Ford Taurus just to name a few. Or from Amazon and elsewhere for about 20 bucks.
     
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  19. anthony myrick
    Joined: Sep 4, 2009
    Posts: 9,999

    anthony myrick
    Member

    Did a mechanical.
    The noise definitely changed.
    I originally used a 68 472 pump cause I had a new one and it’s smaller. But it uses 5/16 line. The 69 up is 3/8. My ride is plumed 3/8. So in haste during the late night work I didn’t notice the piece of 5/16 line we scrounged up to plumb the carb.
    If the pump was bad or not, I feel much better with it all plumed 3/8. The 500 was idling very smooth but missed and hesitated while driving. Timing changes didn’t affect that. So I’m guessing we were starving the q-jet.
    081680CF-7E10-415A-8F90-D135A3DBAD8F.jpeg
    the damaged 5/16 line we were using is on the left. I lot different than the new 3/8.
    The new pump has a return. I may go ahead and plumb that in.
    Now to make sureI have the correct carb gasket.
    I still hear some valve train noise but nothing like before. We’re going to slowly figure this out
     
  20. anthony myrick
    Joined: Sep 4, 2009
    Posts: 9,999

    anthony myrick
    Member

    Test drive. New correct gasket, re-torque intake, adjust carb and timing.
    Still misses or sputters during a pull.
    Cruises fine until ya get in the gas. :(
     
  21. triumph 1
    Joined: Feb 9, 2011
    Posts: 583

    triumph 1
    Member

    Possibly lean misfiring under higher load?


    Sent from my iPhone using H.A.M.B.
     
  22. anthony myrick
    Joined: Sep 4, 2009
    Posts: 9,999

    anthony myrick
    Member

    Possible.
    We’re going to look in to possible carb issues and distributor issues
    I do know the carb is getting fuel now.
     
    Last edited: May 18, 2021
  23. Boy ,that clunk sure moves around ;-)

    For the record, y'all... The hub is in the back of the converter. The pilot is in the front.
     

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