Martin Hill
I'm New Here
I bought into a IO-360 that sat in a barn for 18 years untouched. In addition to the sitting in Eastern Virginia unused, it has an old-style crankshaft with the light-duty flange, so we decided a teardown was in order. It also has a superior cam that has timing that is slightly off.
Superior's SB that covers the cam basically states that "we tested it, works fine and essentially meets spec despite the angles being slightly different than lycomings and should make rated HP". (below)
Does anyone have any pre-internet knowledge on anything further with this camshaft?
SB 93-01 text
"In July 1991, Superior Air Parts, Inc. reintroduced P/N SL18840 replacement camshafts for Lycoming 320/360 engines. These camshafts were designed, engine tested and approved during a rigorous FAA certification program.
After introduction, it was brought to Superior's attention that the valve timing was slightly different than that of the OEM. Although there were no anomalies noted during the certification testing and no reported field problems, Superior believed it appropriate to review the timing issue. Industry experts were consulted and there was agreement that such a minor difference would not affect engine operation. However, to resolve the issue and end unproductive speculation, Superior changed the SL18840 valve timing to agree with that of the OEM. This change was incorporated in
camshafts shipped after February 1992.
To further substantiate that the pre 1992 camshaft timing difference would not affect engine performance, the FAA, in conjunction with Textron Lycoming, conducted a back to back engine test. Engine performance was measured using a Lycoming camshaft and then a Superior camshaft in the same engine. The difference in performance, considering engine build variations and test cell uncertainty, was confirmed to be negligible."
Superior's SB that covers the cam basically states that "we tested it, works fine and essentially meets spec despite the angles being slightly different than lycomings and should make rated HP". (below)
Does anyone have any pre-internet knowledge on anything further with this camshaft?
SB 93-01 text
"In July 1991, Superior Air Parts, Inc. reintroduced P/N SL18840 replacement camshafts for Lycoming 320/360 engines. These camshafts were designed, engine tested and approved during a rigorous FAA certification program.
After introduction, it was brought to Superior's attention that the valve timing was slightly different than that of the OEM. Although there were no anomalies noted during the certification testing and no reported field problems, Superior believed it appropriate to review the timing issue. Industry experts were consulted and there was agreement that such a minor difference would not affect engine operation. However, to resolve the issue and end unproductive speculation, Superior changed the SL18840 valve timing to agree with that of the OEM. This change was incorporated in
camshafts shipped after February 1992.
To further substantiate that the pre 1992 camshaft timing difference would not affect engine performance, the FAA, in conjunction with Textron Lycoming, conducted a back to back engine test. Engine performance was measured using a Lycoming camshaft and then a Superior camshaft in the same engine. The difference in performance, considering engine build variations and test cell uncertainty, was confirmed to be negligible."
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