I have the static timing at 18 degrees and have limited the mechanical to 18 for a total of 36.
Are u runing EGR? if not ideally u should have manifold vaccuum and the idle made up of intial + VA
So if your ideal (best stable idle at lowest prefered rpms and mixture slightly on lean side) idle is 18 .. And your best performance/ power is 36 deg with a rich mixture....it is un wise to have more than 40/ 42 deg initial+cent+ VA without dialling in with a knock sensor
so 41 deg less 36 gives a VA max of 5 deg
And if ideal idle is 18 18 minus 5 gives an intial of 13 degs
The VA needs to be all in at idle vacuum.. or no more than 1/2 to 1" above.. MAX
It also need to be all in at approx 60 mph flat road and '1/4 acceration... and start to come in when hit a gentle slope
Of not thu.. with modern pump fuels, cam designed stc I doubt very much that 36 deg is your best total (intial+cent) advance... ball park would more likely be around 32 @ around 3000/ 3200 rpms
This would then give 41-32= 9/10 degs in the VA
idle still 18 intial 18-9= 9 deg and
cent 32-9= 21 deg .
Now a couple things to watch
I mentioned above where a counterweight can fall off the sliders and over the edge above
If a VA is not all in at idle (non egr on manifold vaccuum) the u are most likey get a idle that speeds up and slows down... as the VA pulls advance increases ,that increases the rpms.. then sice u are running on the fixe metering carb idle circuits.. the engine runs out of fuel to maintin those rpms slows..the Va start pulling again....repeating
And a similar effect if the cent springs are too light and dont hold the counterweights in at idle... I run a very fast cent curve because of the propane fuel and highe octane and over 11:1 compression.. so push the limits here... my idle in gear is a very stable 550 450 in N(because of propane) and they come off around 700 rpms and the curve all in around 2600.
For a petrol engine which needs slower curve but more advance up top... the all in around 3000/ 3200 will have the weights coming off around 1200 to 1500 rpms
300 to 500 rpms above idle speed
Another thing to watch is that the carb secondary butterflies MUST BE set corectly, and the carb IS idling on the idle circuits only.
The stop limiter plate at this end is not recommended as it puts stress
and a constant load on the VA spring.
Strip out a VA and see how big that spring is....also u will find that the spring is already loaded inside the canister anyway... and in real world , the diaphamn will perish and get a hole yrs before the spring gives up the ghost..and if it doesnt the spring will rust and break 1st.
If anything if the VA mounting screw is not screwed in , torqued correctly the spring will damage the mounting hole threads.. and this can occur at the other end.. that diaphamn pulls far more pressure on that lever than the spring can ever apply.