Avidflyer2
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TCM Continental IO-360 Engines as equipped with PN: 631654 "Roto Coil Assembly" (valve spring retainers) - on top of each intake and exhaust valve spring. Valve rotation is, in theory, able to even out wear and possibly eliminate hot-spots during engine operation.
The rotocoil assembly consists of an inner and outer bearing race with ball bearings separating the two races. This arrangement is supposed to allow the inner race to spin or rotate with the valve stem while the valve springs remain stationary. The rotational force comes from the rocker arm tip as it wipes off-center across the tip of the valve stem as the rocker arm first depresses the valve and then relaxes pressure on the valve stem. The rocker arm is then allowed to "float" a little bit as the valve lift is reduced to zero - even though a slight pressure is exerted by the "zero lash" hydraulic units or lifters. I can see where this will at least impart an oscillation in the valve stem as the valve is repeatedly depressed and let up again, perhaps as a way to even out valve guide to valve stem wear, or as a matter of heat transfer.
The problem is upon removing the rocker arms and inspecting the rocker arm tips, I'm seeing a flat wear area the diameter of the valve stem suggesting that the rocker arm tip is no longer imparting a rotational force to the valve stem. For that matter, I have not found a specification in the overhaul manual for resurfacing the rocker arm tip to restore a radius or angle in the contact area to provide a off-center push to rotate the valve stem. Once the rocker arm tip wears flat with respect to the valve stem there isn't any way to impart a rotational force to the stem.
My question is whether the rotocoils are expected to rotate or oscillate the entire engine TBO period as it is evident that they fail to do so. How are the engine overhaul shops resurfacing the rocker arm tips?
Does anyone have a video of the valve train in operation, specifically showing the intake and exhaust valves rotating?
The rotocoil assembly consists of an inner and outer bearing race with ball bearings separating the two races. This arrangement is supposed to allow the inner race to spin or rotate with the valve stem while the valve springs remain stationary. The rotational force comes from the rocker arm tip as it wipes off-center across the tip of the valve stem as the rocker arm first depresses the valve and then relaxes pressure on the valve stem. The rocker arm is then allowed to "float" a little bit as the valve lift is reduced to zero - even though a slight pressure is exerted by the "zero lash" hydraulic units or lifters. I can see where this will at least impart an oscillation in the valve stem as the valve is repeatedly depressed and let up again, perhaps as a way to even out valve guide to valve stem wear, or as a matter of heat transfer.
The problem is upon removing the rocker arms and inspecting the rocker arm tips, I'm seeing a flat wear area the diameter of the valve stem suggesting that the rocker arm tip is no longer imparting a rotational force to the valve stem. For that matter, I have not found a specification in the overhaul manual for resurfacing the rocker arm tip to restore a radius or angle in the contact area to provide a off-center push to rotate the valve stem. Once the rocker arm tip wears flat with respect to the valve stem there isn't any way to impart a rotational force to the stem.
My question is whether the rotocoils are expected to rotate or oscillate the entire engine TBO period as it is evident that they fail to do so. How are the engine overhaul shops resurfacing the rocker arm tips?
Does anyone have a video of the valve train in operation, specifically showing the intake and exhaust valves rotating?
