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Thread: intermittent knock, Please help!

  1. #41
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    That would make the intermittent nature make more sense.

  2. #42
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    Quote Originally Posted by bmorgil View Post
    Excellent on the oil pressure. You are narrowing it down now. The cylinders with the low compression are probably the culprit. When the piston strikes the valve it can bend it. This usually causes a bad seal and aggravates the "sticking". You can pull the rocker shaft and exercise the intake valves. If one is sticking, it should show up when you manually open and close them. They usually stick as the valve is close to closing. The spring pressure is at its lowest.

    If that's it, a valve job is a lot easier than a full tear down!
    How would one manually exercise the valves? Turning the harmonic balancer?

    Edit: Are you saying remove the rocker shaft?
    Last edited by monty509; 04-20-2020 at 02:31 PM.

  3. #43
    Super Moderator bmorgil's Avatar
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    Yes, remove the rocker shaft. However before you do that you should be able to easily make this happen. Pull all the plugs to make it easy to rotate the engine. If you can rotate the engine by hand with a ratchet and a socket on the crankshaft. Remove the Intake valve cover and turn the engine over allowing it to compress and release the valve springs. Go slowly and see if you can feel it bumping a valve. As they close, watch each one to see if it suddenly "Jumps" shut like the piston is pushing it, or it doesn't close all the way. When it appears to be closed check the lash. If you suddenly have a lot of lash, rap the top of that valve and rocker shaft to see if you can get it to seat further. Use something to try to pry the valve up if you can. If the lash closes up that valve is sticking.

    There are a few ways to exercise the valves. What I would try first (after removing the rocker shaft) is to simply rap the valves with a soft hammer and see if they do not fully return. To be sure, you can use a valve spring compressor like this https://www.harborfreight.com/univer...sor-60335.html to remove the springs. Then you can easily move the valves to see if you have a valve sticking. You need to be careful when doing this. You do not want to drop a valve into the cylinder. The piston must be at TDC when you remove the valve spring.

  4. #44
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    Okay a little update, haven't forgot about you guys. So removed the covers and rotated the crank and inspected the valves, nothing unusual, put back together to take it to my fathers shop. The thing wouldn't start, rechecked the points, plugs, wire ect. Seemed like some of the wires going into the cap hoods had moved making bad contacts from wire to cap. Bought some new wires and bingo started, with a very slight knock. Let it idle for about 10 minutes which was rough. Once it smoothed out a little bit I started to mess with the carb settings as I adjusted them and the idle smoothed out and slowly the knock got quieter and quieter. Now the idle isn't set perfect cause I'm no expert at It. I got it to idle pretty well on its own with a little sputter for about 10 minutes and decided to take it for a small trip around the block, I backed it out of garage and went over a little bump and it shut off and wouldn't start again. Smelled a little rich so I think I'm still a little off on the right settings. If anyone has any tips/tricks on setting them I believe this carb to be a solex replacement, not 100% sure though. I don't think I'm out of the woods yet though but one more thing off the list. I gotta wait for the battery to charge as I ran it dead trying to start the thing. So tomorrow I'll post a video of how it sounds. I also got a mechanics stethoscope and probed everywhere. I don't hear anything that doesn't sound like a mechanical sound, just maybe, fingers crossed here some very light detonation. Lets hear your thoughts, open to any suggestions. Anyway hope everyone is well and enjoying their weekend, mine just got a whole lot better.

  5. #45
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    All you can really adjust is idle mixture and idle speed. Screw the idle mixture in until it tries to die, then back out and leave it at the spot where the engine is the highest RPM. On idle speed you just put it where it sounds right for you. Might have a loose electrical connection making it shut down.

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