Edgar Franks quotes 52deg BTDC for the prewar Inters. But the post war value is 42.5 deg. There was, of course, only Pool petrol for rather a long time after the War. Does anyone know if that's why? I think I'll see 53 deg (I make that as much as 24mm piston drop), but mark 42.5 deg(16mm). So it gives me the chance to select more advance.
Any advice welcome. It's a p** to start at present. Mag cable is opposite entry direction to my 16H and I foolishly assumed it was tight wire advance....it's not!
I see George Cohen said 37 degrees. So neither of the book figures... anyway, hopefully it will be easier to start.
Looking at the first picture you sent in, it looks like you have the wrong mag fitted. The advance/retard cable should exit nearest the engine which means you do have a tight wire advance.
The ES2 is 100mm stroke, the same as the model 30, but is 45 degrees or 5/8" (fully advanced) with lower compression than the Inter. 42 degrees is correct, but this can vary slightly depending on which fuel you use.
Ignition timing is dependant on compression ratio and type of fuel, 37 degrees would be for around 9 to 1 comp. on premium petrol.
With the engine cold try the ignition and the air lever halfway, and flood the carb. Keep the throttle closed but be ready to "catch it" when the engine fires, a valve lifter is a must, unless you bump-start it.
Thanks Richard. I expected slack wire advance, and saw the wire entry on opposite side from my 16H....could have injured myself!
PO left notes on compression ratio. I'll check and hopefully get it going this afternoon. I think it's about 9 to 1.
If your Inter is 9:1 you probably have a Manx piston and no compression plates. That's at the high end for a long stroke sohc Norton. It would probably be better to drop the ratio a bit, if only for easier starting. Once it's running OK you might consider raising it again if you wish.
The BTH racing mag, and Lucas MagDyno which I have are both tight wire for retard, and gives a weaker spark than on full advance. The standard ignition timing is 42 1/2 degrees for a low compression Inter, 7:1. There are probably people in the NOC who will remember what settings will work on higher compression.
Hi Paul (again.. I feel a bit ashamed of myself for all this cross posting, but it's been a steep learning curve...).
According to the extensive notes and if I have the final values, I think it is at 8.5. I set the timing (which is tight advance for some reason) to 37 deg BTDC on thin red lines on the lever, so I have a small amount left to pull.
Anyway.. much to my surprise I seem to have sorted starting it.
Routine I use is
Turn over, using lever just at the peak of compression, with a couple of fingers over the air tube just to make sure there is gas all the way in
Retard on lever about 1/4" between my red lines
Bring up to comp, decompress over TDC
Tiny throttle and slide down.
Kick start. Often first kick, usually within 1st three.
On Tuesday it started when warm when I was just turning over on part compression.
The thing to remember is to pull back to advance and open throttle very slowly. None of that 'blip the throttle' business...
I've read up about the air slide, but mine doesn't seem to have any noticeable effect. I don't know if that is usual.