The International Cessna^® 170 Association

The IPC for the C-125, C-145 and the 0-300 call out two different part numbers for the rocker arm assemblies to be installed. 639615 exhaust and 639614 intake. The difference being an oil squirting orface in the exhaust rocker to lubricate the rocked tip and valve stem. The intake rocker this orface is omited. Upon dissasembly of my engine and other engines I've worked on I find the 639615 installed in both locations. As an A&P/IA I find this to be puzzling. I'm in the process of doing a Top ovhl on my 0300-C and of course be in complience with current publications. Is there a publication that I may have missed giving instruction on using the 639615 in both locations, or is this a case of mechancs trying to do a better (they think) job? I'm trying to do it right, as it's my name in the log book (return to service).
Anybody run into this and if so what did you find?

I checked the continental web sight and found the 639614 to be a superseded part number. There was also no SB or SIL concerning the substitution of the 639615 in place of the 639614. Strange to say the least.

I believe the 639615 (drilled) rocker is approved for both positions, but it is not mandatory for the intake position. I'll try to locate where that is so stated by TCM, but I do recall the matter.

TCM Service Bulleting "M77-19" was issued Aug '77 to instruct that PN 639615 (with oil orifice) was to be installed in the exhaust position and that PN 639614 was an un-drilled part which is to be installed in the intake position. The bulletin intent is to insure that the lubricated rocker is placed correctly.