Combustion stroke on non combustion stroke for TDC

YES - thank you - that was the answer I need (that the bottom of the engine is always at the same position) which caused the penny to drop and see why I was over thinking. Its the worry of reading online the dire warnings of pistons smashing into open valves - that got me truly concerned to get this right. I normally tackle everything pretty easily and have restored cars and other mechanical stuff for years - but for some reason - I just began to worry that this "overlap" that everyone is talking about

Anyway - I get it now - so tks guys. Onwards we go

Rgds

Greg

Hi I have one more question please for you experienced guys .

In the drawing from the manual in this thread that Scirocco posted ( I do have a manual but don't understand the below statement) - At the bottom of the drawing it says :-
"NOTE: 1. The 1 4 "T" mark on the automatic timing advancer must be aligned with the right engine cover mark"

So - 1. What/where is the " automatic timing advancer"? (whats automatic about it?)
2. When they say "right" engine mark - do they mean "correct" engine mark or "right hand" engine mark. (AND WHICH IS IT?)

I am assuming we are talking about the timing plate/disc under the RH engine timing cover with the hole in it to see the TDC mark but it seems they do not mean the TDC mark?? (otherwise why didn't they say it ? )

I am assuming the 1 & 4 they refer to are cylinders 1 & 4 when in TDC ?????? (please clarify this tks)

If I can make sure I understand the note perfectly - then I am set thanks.

The ATA is behind the timing plate. You can see it through the hole in the timing plate, the bit with T, F, 1 and 4 and 2 and 3 stamped on it.
It basically operates by centrifugal force and sprung weights. As the crankshaft spins the weights are "flung" out by centrifugal force with the springs regulating how far they are "flung".

If the T mark on 1 and 4 side on the ATA is aligned with the mark on the crankcase then yes 1 and 4 are at TDC.

Different model advancers have both a T mark line and an F mark line, but vary in exactly where the letters T and F are placed in relation to their respective lines. But it's usually fairly easy to determine which line is the T mark line and which line is the F mark line.

Here are just a couple of examples:



When the engine is running, a timing light is needed to see the "twin" advance marks through the window.



Being "automatic" means that the advancer automatically advances the ignition timing as revs are increased.

Don't be confused by the different type "rotors" used for points or igniter or Dyna ignitions.




Good Fortune!