41 model h cam/flywheel mesh noise

Have a noise coming from what I thought was gov/fan shaft area. Took off fan shaft and still have the noise. Thought it might be in gov assembly which has been totally rebuilt but everything checked out as far as I could see with engine running. Took the whole gov off a few days ago, took out spark plugs and spun flywheel as fast as possible and heard a clanking metal sound which I believe thru deduction is the noise I originally heard... Could visually see this noise is coming from the gov/flywheel meshing @ every full revolution. Just by chance I had a friend spin the flywheel with the clutch engaged while I held back the clutch pulley actually 'braking' it and keep it tight with the flywheel. Low and behold no noise. Does anyone have a clue as to what might be going on with the camshaft or parts within that would cause this momentary delay of the cam meshing with the flywheel while the engine is running ??? Thanks and appreciate any help.

Camshaft gear bolted onto the camshaft gootentight? Can be a problem in larger 2 cylinder, not sure how yours is even put together as I couldn't find yours in the parts App for 1,600 lime spreaders in the way.

Don't see how applying a slight drag to the clutch pulley cure's much other than excessive crankshaft end play by accidentally keeping it to non-noisy side. So I have to wonder if it's excessive end play?

Drag on the clutch pulley would hold the clutch operating sleeve still too, perhaps that is what is clanking around in there?

The LH cam bearing is a ball bearing and it controls end play on the H cam. Most are bad and need replaced. I think by '41 you have the 4 bolt casting which is eccentric so you can adjust the backlash of the cam gear. Most likely mark it before removing it put a new bearing in and reinstall it in the same position.

Tried all 4 position of the left bearing housing to no avail. Noise is definitely coming from the cam/crank mesh. This has been a ground up resto and all bearing replaced. This is not to say I didn't fudge something or missed a bad part somewhere along the way. Wether I hold back the clutch pulley or the cam gear itself the mesh stays tight and no clinking of the gears. Looks like I'm going to have to take the clutch/cam assembly off piece by piece to figure this one out...

Remember, the H belt pulley is driven by the camshaft not the crankshaft. When the camshaft gear lash it too great, the crankshaft and camshaft teeth hammer on each other as the cams go over center under the pressure of the valve springs. With the load of the governor and fan shaft removed, it's MORE noticeable.

The camshaft gear "hammers" on the crank gear as it changes from being driven by the crank (when lifting valves) to being driven by the valves (last ones closing) and it changes from being driven by the crank to trying to push the crank. It then coasts (no cams in operation) until LH EXHAUST begins to open. Applying some drag to the belt pulley overpowers the pushing force of the valve springs on the camshaft and stops the hammering making the gear train quiet.

If you engage the clutch (transmission in neutral) and roll the engine by hand until #1 has just sparked at the top of the compression stroke, if you grab the belt pulley and "rotate" it forward and back quickly (shaking it sort of), you're likely to hear somewhat that same noise.

As others said, check the camshaft gear lash (assuming the gear is tight on the camshaft) and if extreme, verify the adjustment of the eccentric left bearing housing.

Another thing to verify.... Loose tappets on an H are rather well muffled by the cast iron valve cover. Are you sure the tappets are not too loose and maybe part of what you hear when it's running is the cam followers slapping the lobes? I know this would not show up at your "hand turned" experiment but running is another matter. Remember they're fairly large L shaped levers instead of the barrel type cam followers that move in line with the push rods.

Hope that helps.

Thanks Buckeye. Pretty much grasp everything your saying except for the 'loose tappets'. Other than setting them at .015 are there any other adjustments I can make or could they just be worn beyond help or if they are could it be possible to set them a few thousands tighter ? I've also considered the cam followers to be a possibility. Could theyalso be worn beyond help ? Like I said I've tried all 4 positions of the eccentric to no avail but I could try again.... Not sure how the cam gear could be loose from the shaft since it's a splined taper but I will check. Thanks

(quoted from post at 10:50:50 07/23/16)
Thanks Buckeye. Pretty much grasp everything your saying except for the 'loose tappets'. Other than setting them at .015 are there any other adjustments I can make or could they just be worn beyond help or if they are could it be possible to set them a few thousands tighter ? I've also considered the cam followers to be a possibility. Could they also be worn beyond help ? Like I said I've tried all 4 positions of the eccentric to no avail but I could try again.... Not sure how the cam gear could be loose from the shaft since it's a splined taper but I will check. Thanks

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Also should mention the clutch pulley turn even with the clutch disengaged. I can stop it with my hand with no problem but when I let go it continues spinning. Not sure what's going on there ?

Should also mention with the tractor running the clutch pulley spins even when disengaged. I can stop it with my hand but never seen another one do this. Not sure what's going on there ?