Nice one always a good moment, re the idle make sure the oil scavange pipes fropm the mains are connected ok and it's not drawing air into the crankcase, otherwise it's go by the set up/tuning in the workshop manual, there's throttle stop/timing syncro to throttle/ign set up at idle and full throttle/full throtle stop/ and the interlinkage to the controls... all adjust! also idle mix on mine adjusts as well...I think!
If you can get it somewhere near, I found that the idle ign advance was the best way to get the idle speed, mind you my engines go the dizzy on it it so yors will be different!!
Idle in neutral on mine just over 1000 revs then it settles to around 600/750 in gear and doesn't stall out.
Well done Dave. I have the OE manual for that here if you need info on how to setup the carb/timing sync & max advance. The max advance is (in theory) set up with the engine running in fwd gear under load, i.e. in the water not on muffs. If it really won't idle the stator is a common reason for this, they can be checked with a meter, again the info is here.
Rapiers decal recommendation is good, I have them on my 6cly. The earlier style decals look much better IMO than the later style you have so you can badge it earlier.
Mercs are like women, no 2 are exactly alike. That's what testing is about. In general it is safer to test motors and props than women!
Thanks for all the encouragement, I Have begun looking at the adjustments starting with the advance pointer setup. I am using a dial guage fitted to a purpose made tdc finder so am convinced the method is right. When No 1 is 0.464" before tdc the pointer needs to be at its maximum position left to point to the mark on the flywheel which makes me think something is wrong
I have heard of this only recently on a US Merc site & I don't know the answer. It might be worth you posting a question on HERE as I would also have concerns. Se7en may pop up with an answer of course but when I set my 6cyl pointer on .464 it 'looks' right if you get my drift. However if it is at one end it makes you wonder if the sticker is in the correct place on the flywheel? Of course .464 is .464 however you look at look at it assuming you are doing it correctly which I don't doubt, so in theory it must be correct. Have you tried giving Duncan Walker a call although its a little cheeky unless you have bought parts from him?
Mercs are like women, no 2 are exactly alike. That's what testing is about. In general it is safer to test motors and props than women!
The flywheel is engraved not decaled so cant be wrong unless its from an earler / later motor with subtle differences. The spare I have is typicaly corroded around the markings so no use. I am using a genuine oe manual so am prety certain the method is correct.
I have bought most of the parts used on this motor from Duncan so may give him a call and get a prop nut and washer too
as Alacrity says, .646 is .646, if you set it to that you can't be wrong, on Jade's engine I marked the flywheel my self, and made up my own pointer, I had to do this as I fitted an aluminium ( non standard) flywheel, when it comes to timming the motor, I run with 2-3 deg less advance, at full throttle than stated in the manual
Have spent the evening making adjustments. Aligned the pointer hard against the stop but correct to the measurements. Set the max throttle opening and max advance (at cranking speed only) to 30 deg as stated on the sticker on the airbox will probably shift it off a couple as recomended by the wise but thought I should begin at factory norm. Set the primary pickup advance which was too retarded and needed a bit of adjustment, hoping this is the cause of the tickover failiure. will try and chip off work early on friday and give it a run on the muffs to check it over.
It might be worth you posting a question on HERE as I would also have concerns. Se7en may pop up with an answer of course but when I set my 6cyl pointer on .464 it 'looks' right if you get my drift. However if it is at one end it makes you wonder if the sticker is in the correct place on the flywheel? Of course .464 is .464 however you look at look at it assuming you are doing it correctly which I don't doubt, so in theory it must be correct. 
