Misc: Ignition Twin Points Ignition

[Chris Launders]

The condensers I have are unmarked.
As regards coils you can run a higher resistance ones with electronic ignition as the system limits the current flow, however with points there is nothing to do this and using too low a resistance coils will allow them to overheat and possibly burn out (I know of two occasions where people have replaced the electronic ignition with points set ups when having problems with their electronic ignition, not changed the coils and burnt out the coils)

 

[bmetcalf]

I see Bruce is talking about a single cylinder, Maybe different ?.

They sent that when I asked about using a double lead coil for my Rap instead of the standard pair of 6V coils in series.

 

[Bill Thomas]

I had a faulty coil on my Mistral Rita on my twin, When new, It was the front one so lost everything !,
2 x 6v type,
Happen to have a 12v one in my tank bag, So thought, Sod it, It's going on there !,
Super !, But the tick over speed went up, Told the Rita bloke , Like other people, He thought I was MAD !.

 

[greg brillus]

The single outlet coils on my racer are 0.3 of an Ohm......... Ignitech crank triggered ignition.

 

[Michael Vane-Hunt]

I also use a 3 ohm Dynatek coil on the Comet.

 

[Monkeypants]

I take it from that it is the synthetic, nylon? rubbing pad which fails on the Daichi points, causing the gap to close?

That's right. Even with the provided lube they would go out of adjustment by 5 thou every 300 miles.
The rubbing block on the original Lucas points looks the same but only changes by a couple of thou at the points in 25,000 miles.

That was my experience at least.
Glen

 

[Pushrod Twin]

So just getting back to this for a minute, in case anybody is remotely interested.....
I have answered some of my early questions, to wit;
Is this the points plate fitted to the Lucas twin points devices used on Norton & AMC twins in the 'late '60's?

It appears the answer may be; yes. While researching some stuff for a friends's Triumph project, I stumbled over an illustration in a Triumph manual labelled "Contact Breaker 6CA" On close inspection, the points plate assembly I have appears to be either the 6CA system or, from an illustration in JB Nicholson, a Norton '67-'69 contact breaker plate assembly.
There is a subtle difference between my plate and the aforementioned, in that my base plate and intermediate plates on which the points are mounted, have been modified to rotate one of the points plates to make it fire at 155 & 205 degrees without altering the cam profile.
So I set the points at.020" as recommended by Glen Monkeypants, attached a degree wheel & adjusted the plates so the points opened 155 & 205 degrees apart.

 

[Pushrod Twin]

That was followed by a desire to know what auto advance it had. Another degree wheel set up indicated only 11 deg, or 22 crank degrees. A few minutes judicious application of a round needle file had that adjusted to around 13 or 14 degrees, depending on my accuracy of measurement.
I wonder if the guy who built this tried it and was disappointed with performance due to lack of advance?
The advance mechanism appears similar to that in another illustration in the Triumph manual, but opposite handed fly weights for opposite rotation.

 

[Pushrod Twin]

Having got that far, I couldn't stop myself, I needed to know if it would make sparks. So with regard to the above discussion around coils & condensers, I chose to use something I am well familiar with, a set of old Guzzi coils and a matching pair of new condensers.
Interestingly, I havent found a published rating for Guzzi coils, however, in the V7 Sport Testing Data & Specifications chapter, the coils primary side should test at 3.35 +/- 6% Ohms, does that make them a 3 Ohm coil? The other thing which I find interesting regarding coil resistance for points Vs electronic systems is; we Guzzi owners use OEM points spec coils attached to electronic Dyna ignition systems with impunity, and to my knowledge, have no failures.
So, grabbed a reject battery and cobbled together some wires then set it all in the lathe. Nothing! Battery measured 7.9V,and with a load I suspect that was a whole lot less. Attached a charger and got 14V, bingo, sparks turning the chuck by hand. That was followed by running at 34 RPM, (17 crank RPM) good sparks.
Next step, hold my beer while I set up a degree wheel and strobe light and see if we can check the auto advance.

 

[vibrac]

Way back when kids played board games I read an article (perhaps in MPH?) about converting a Lucas distributor back plate to fit 2 set of points I used one of those distributors off a late model 50 Norton including the neat three point alloy housing (I had about 3 of those engines and gearboxes from my Continental Circus buddies who were taking the FB frames to flog at the circuits ) It worked well enabled accurate setting of each cylinder and went on my twin untill I could find another decent mag . I have never found where I read about it