Patrick,
It is possible to transpose the cam gears. From 1925 to 1926, the inlet cam is the one with the drive slot on its hub. This was to drive the gear type oil pump, used on engines up to about YE6500. After that, the oil pump was a rotary plunger type drive via a worm in the crankshaft. However cam wheels with redundant drive slots probably were still fitted to the inlet until stocks were exhausted. By c1927 they must have deleted this drive slot, as the spares list for that year just shows one cam wheel for the inlet/exhaust; part number c/8316. I do not have a spares list earlier than 1927 for the EW, to know offhand what the earlier cam numbers were. But it really does not matter, because-
Both cams have the same 245 degree duration according to the EW handbook (including the 1925-26 models), so either can be timed as a inlet or an exhaust. Though if you are using the original timing marks, things could get a bit interesting in the valve event! If you ignore any spurious marks and time it to the diagram in the handbook, you will be o.k.
Or by the numbers:
IO 15 degrees BTDC
IC 50 degrees ABDC
EO 50 degrees BBDC
EC 15 degrees ATDC
Inlet and exhaust valve lash 0.006" engine cold.
Without having an engine apart in front of me, I never really understood why they included a distance collar (part #8412) for the cam wheel. The axial location is determined by the tappets (am followers) on either side, not the length of the cam hub.
-Doug
