Belt Slippage
Hal,
Assuming the belts are reasonably tight, and there is no issue with non-concentricity of the rear sheave (you said there was no run out), I still think it is the clutch output pulley that is slipping. The primary drive has a 2:1 advantage over the clutch output pulley, so the load is considerably lower on the primary drive than on the secondary drive, which forces the load to the small secondary pulley. This is also the pulley that has the least belt wrap.
Like I said it's a balancing act between front and rear. I usually start by tensioning the rear belt to my satisfaction, being sure I haven't got the chain too tight etc, then move to the engine and slide it forward or aft to tighten the front belt, without unduly loosening the rear belt. It may also be possible that you simply don't have enough spring tension on the clutch arm and you may have to crank that up a bit too. Keep feeling the belt tension, assuring that it is balanced for and aft, and as you keep tightening things (clutch arm spring and belts) you will prevail in the end.
The belts need to feel darn tight when you're pinching them. Is the top of the rear belt positioned proud of the clutch pulley OD or is it sunk into the pulley? If it is either flush or sunk down inside the pulley at all it's worn (lost some width) and won't grip anything like a new fresh Gates belt.
Hal,
Assuming the belts are reasonably tight, and there is no issue with non-concentricity of the rear sheave (you said there was no run out), I still think it is the clutch output pulley that is slipping. The primary drive has a 2:1 advantage over the clutch output pulley, so the load is considerably lower on the primary drive than on the secondary drive, which forces the load to the small secondary pulley. This is also the pulley that has the least belt wrap.
Like I said it's a balancing act between front and rear. I usually start by tensioning the rear belt to my satisfaction, being sure I haven't got the chain too tight etc, then move to the engine and slide it forward or aft to tighten the front belt, without unduly loosening the rear belt. It may also be possible that you simply don't have enough spring tension on the clutch arm and you may have to crank that up a bit too. Keep feeling the belt tension, assuring that it is balanced for and aft, and as you keep tightening things (clutch arm spring and belts) you will prevail in the end.
The belts need to feel darn tight when you're pinching them. Is the top of the rear belt positioned proud of the clutch pulley OD or is it sunk into the pulley? If it is either flush or sunk down inside the pulley at all it's worn (lost some width) and won't grip anything like a new fresh Gates belt.
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