Can someone confirm that this arrangement is good, the key faces the rear cylinder (dot on the gear).
Hi Phil,
Keys and timing marks are good things to talk about on a new - or nearly new - engine, but one something pushing 100 years old it's best to ignore them entirely. If they line up where they should, excellent, if not parts have possibly been changed or altered.
Your photo at the top looks good is the rear cylinder is at top dead centre, but no promises about the mag!
My suggestion would be to put a pointer at the top of the flywheel, and put a mark with a texta pen at TDC. Then, for each cylinder, check where each valve opens and closes: the chart Doug links to says inlet opens 15 degrees before TDC, exhaust closes 15 degrees after. In your pic, the exhaust is just closing and the inlet just opening - in an old engine this is usually roughly symmetric about TDC. (Amazingly, in some old engines the inlet didn't open until maybe 10 or 15 degrees after TDC!) If you rotate the engine forwards through one complete turn you should have much the same opening/closing pattern of valves at TDC on the other cylinder.
If the inlet opens/exhaust closes is OK for both cylinders you should be right. You can check where inlet closes and exhaust opens, but there's not too much you can do if they'e wrong due to wear/old age/wrong parts.
Looks like there is some vernier adjustment with the three keyways on the half time pinion? You might be able to get better valve timing, even if your marks no longer align.
Leon
