EDSRX3

Timing light I'm using has a Tach readout. Engine is a 12a with a direct fire ignition.

When I use the timing light the rpm's are off the scale.

My logic is..... 4 stroke engine fires #1 once every 2 rotations. Rotary engine fires #1 leading twice every rotation. Direct fire uses waste spark.

timing light RPM will be 8 times actual??

does this make sense?

lastphaseofthis

iTrader: (8)

direct fire, is not waste spark, thats like saying blue is orange. which is it?
waste spark=2 leading events, 1 trailing per SHAFT revolution.
direct fire=1 leading event, 1 trailing per SHAFT revolution.

EDSRX3

I may have terminallogy wrong. This is what I've done.

I've removed the leading ignitor and trigger a MSD to fire 2 coils wired in parallel and bypass the distributor. Each coil feeds a leading plug. Thus the waste spark.

Trailing plugs fired via the distributor and a single coil triggered by the stock trailing ignitor.

I have not tried it yet, but the trailing plug should give me ½ the RPM as the leading on this timing light.


I don't understand your number of events per shaft rotation. Don't 2 of the 3 rotor faces get a power stroke per rotation of the eccentric shaft?

lastphaseofthis

iTrader: (8)

1 combustion event per 1 revolution, on 1 of the 3 rotor faces.( for one rotor)

3 shaft revolutions equal one rotor revolution, and there for a power "stroke" 3 times, 1 on each face.

2 rotors means 2 combustion events per revolution, one for each rotor, 180 degrees apart.

EDSRX3

Thanks! cool, that’s my error. Makes sense that the eccentric lobe would be in the same position relative to the rotor at the power stroke.

That means with my ignition set up, the RPM on the timing light is out by a factor of 4 on the leading and a factor of 2 on the trailing.\

My 3900 RMP idle is actually less than 1000.

Kentetsu

But his leading ignition will fire once when it is supposed to, and then again when it is not needed. Both leading plugs will fire at the same time, but only one will actually cause a combustion event. Hence the term "wasted spark".

So, based on that, I think you are right. Your mini tach will show either 4 or 8 times the expected rpms. Timing lights with a **** for advance adjustment are not rotory friendly either for the same reasons.




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EDSRX3

Ok!

Can you help me understand the problems with the timing advance feature and rotaries.

The unit I have has a digital advance. I was hoping to be able to figure rotaries and timing!

With this build I'm well over my experience. In past I just put a used motor in and run it until I kill it. I never played with the timing.

This keg is a half bridge. I've gone back to an old school intake and have messed with a stock carb, pulling the venturies, hoging them out on the lathe and put in larger jets. I've got the timing set by ear now so it'll fire up easily. I've never had a rotary idle so low, it still respondes great when I punch the gas - no hesitation. Want to be able to measure where it is for fine tuning.

Then there is the oil leak at the cooler - must be cracked. The Alternator conversion I did is not charging and the Tach is dead. I have details to mess with. Other than that I had every bolt off this car and rebuilt or replaced everything except the tranny and the steering box. I guess a few problems were expected.

Thanks for the help!

Kentetsu

lol, sounds like a heck of a project.

What you really need, is just a plain jane timing light. Yours has the tach, the digital advance, etc. and I think it is exactly those bells and whistles that are throwing you off.

Leave the tach alone, just make sure that your idle is under 1,000 rpms. Leave the digital advance alone, you don't need it.

To set the leading timing, you turn the dizzy.
To set the trailing timing, you slide the advance pod in/out.

If you have a Haynes/Chilton's manual, they have decent instructions. Otherwise you can find downloadable copies of the service manual all over this sight.

Good luck.

EDSRX3

Ok~ so more help needed with the timing.

I got the oil leak fixed and got the alt and tach working fiine. Converted to a new aluminum rad and electric fan when my fan clutch failed and ate my original rad.

It starts easy, idles nice. Have not had it on the road yet.

When I check the timing using the front leading plug(bottom plug, front rotor), the timing marks will disapear. This happens at idle, but not consistantly. The revs don't seam to change, but I need to monitor that more closely. If I snap the gas to bring up the revs, the marks come back.

I've checked connections and messed with the wires while its running to if I can change things? Only changing the revs does it. I still need to try it all with the training coil disconected to see what happens.

I'm trying to see what the pully is doing with the timing light. I expect with the waste spark that the timing light will fire when the rear rotor leading plug fires. Yet when I look at the mounting bolts on the pully I can see different bolt head appearance when the timing marks are not visable compared to when they are there???????

I'm not happy with the electrical conections at the distributor for the MSD unit, so I'm mess with that, but I don't see these symptoms with an electrical failure there.

I don't understand how the pulses are generatedin the distributor. Could I only be triggering the rear rotor, so the spark I get in the front rotor is just the waste spark and triggers the timing light? Got to see what the timing light tach says when the marks disapear.

I have a few extra distributors to swap out and see if it goes away.

Any ideas? Anybody else notice anything odd using a timing light with the extra spark??