light speed on left, slick on right

[stringbender]

Recently purchased RV6A, high CHT's, it appears to be a difficult to time the light speed standing in the cockpit and using a timing light. Anyone accomplished that?

The right mag is a slick and it makes the clicking sound for impulse coupling.
The engine has an intermittent bump when hot usually around take off. I am contemplating removing the slick all together, I just don't have any records of the mag. Also the engine runs so well on the light speed I am thinking its doing all the work, and including retard spark for start?

What mag would be a good combination (not adding another battery)?

[Carlos151]

I run a Plasma III for the top plugs and replaced my Slick impulse mag at about 350 hours with an E-mag for the bottom plugs. That combination works great for me. E-mag is super easy to time and I agree the Plasma is a bit tougher but once you get it timed I have found zero drift over the last 6 years. With that combination I'm seeing 170 KTAS running 23/23 and burning 8.1 GPH LOP. Before replacing the mag I was at 8.4 GPH so there was a slight improvement on the gas mileage.

[Carl Froehlich]

You must verify the timing of the Lightspeed with a light. This is a two person job, don’t try it by yourself. The second person stands forward of the wing to do this.

I found an RV-7 with dual Lightspeed with CHT from day one running 400+ no matter what. Verified install correct. The timing light showed that both ignitions where stuck on full advance (close to 40 degrees) no matter what the engine was doing. They finally went back to Klaus for repair.

I run dual pMags, and recommend that setup.
Carl

[stringbender]

I have resolved the high CHT issues. Re-jetting the carburetor , fixing the cowl, baffle rubber replaced.

The pressure sensor on the Lightspeed is critical to the performance, if failed the timing goes full advanced.

I had to use an old timing light, stood up in the cockpit, thanks to a slider and use reflective tape on the backside of the ring gear to highlight the timing marks. Everything is fine now and I love that light speed. Engine starts like a car.

[scsmith]

I have a lightspeed on the left and a slick mag on the right. I start on the lightspeed only. The mag is not impulse coupled.

If the base timing on the Lightspeed is more advanced than the mag, you will have higher CHT and will have the feeling the mag isn't doing much.

I'm not convinced on your comment about the MAP sensor failure causing full advance. Perhaps it depends on how the sensor fails, but if it goes to zero output, or if you open the pressure line to it, the Lightspeed will go to the base timing - no advance.

[Toobuilder]

There are some well documented examples of lightspeed MAP failure = full advance on this forum. Its one of the reasons I program my SDS ignition to default to base timing at the extreme ends of the MAP range. Both SDS and lightspeed use the similar GM style MAP logic.