Surefly ignition with a lightweight prop?

My mags are coming up on 500 hours. I have a Surefly sitting on the shelf that I got a deal on, and was planning on replacing one of the mags when they were timed out. I heard that there was an issue with kickback on lightweight props, and I'm running a Whirlwind RV-200.

Anyone have any experience here?

TIA

I had a Whirlwind RV200 on my RV8 with two E-mags and got a kick back during start, which broke a couple teeth off my starter ring gear. Fortunately, the starter wasn’t damaged. I ended up resetting my start timing to fire at 5* after TDC. If you do that with your SureFly, you’ll also carry that 5* offset throughout the advance curve. Max advance will be 5* less than design, so maybe 30-32*, which might not be a bad thing. Your after start fixed timing will also be offset, so your 25* engine will be a 20* engine. I don’t think you would be getting full takeoff power doing it that way. I talked to the folks at SureFly about this, and they told me to just set it as described in the install manual (at TDC). He said they haven’t experienced problems with kickbacks if installed per the manual.

My engine builder (JBA) told me the kickback could also be caused by my improper installation of the sniffle valve on my forward facing sump engine, which didn’t allow all of the residual fuel to drain out of the intake manifold area. Somehow this residual fuel can be drawn into a cylinder and fire at the wrong time. Our electronic ignition systems use a wasted spark, so when #1 is firing, so is #2. If that #2 piston is just starting up the cylinder and there’s the right combination of fuel and air, that nice hot spark created by your EI could fire causing a kickback. I ended up modifying my sniffle valve install correctly and also reset the timing, so I don’t know which one worked, but one of them did. Never had a problem again.

Any disadvantage to running an impulse mag on one side, and a surefly on the other? So both sides make a spark during startup? My primary concern is to eliminate the hot start issue.

I’ve been running a Surefly EIS on my Continental O-520 swinging a 3 blade MT prop. In the year I’ve had it installed, I’ve never had a kickback, or any other issue.

Sure Fly & Mag

We run one Sure Fly and one original MAG on our RV10 with IO-540-D4A5 with MT 3 Blade and dual batteries. Never had any kickback, starts quickly just like a New Automobile every time.

Scott Hersha said:

IOur electronic ignition systems use a wasted spark, so when #1 is firing, so is #2. If that #2 piston is just starting up the cylinder and there’s the right combination of fuel and air, that nice hot spark created by your EI could fire causing a kickback. .

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A properly designed wasted spark system will fire one plug near the top of the compression stroke and the other plug near the top of the exhaust stroke. In the latter case, Valves are open and no fuel in the cyl. Therefore zero potential for the wasted spark igniting something. Even if there was somehow fuel in the cyl, a spark CANNOT ignite a air/gas mixture if it is not compressed to a degre and this can't happen with the exhaust valve open; It stays open well past TDC.

Larry

So Larry you are saying that there's nothing to gain by retaining the impulse coupling on the Magneto?

I spoke to Bill at Surefly about the kickback problem. He said that if the blade stalls during startup, it would be possible to have a kickback as the Surefly will fire at TDC no matter what. For whatever reason, my engine does tend to stall at TDC when I crank it over. I replaced the battery, PC680 in the rear baggage. Next thing to look at is the starter itself. Bill says it should maintain a minimum of 10 volts or better while turning over.

Moe, one of the least desirable things in a conventional mag is the impulse coupling. They do break and come apart, so I believe most people replace the impulse mag with the Electronic mag to eliminate this potential failure. On my old race car, I used to crank the engine then flip the ignition once the engine was spinning fast and it would never kick back.. is it possible to do that with the Surefly by having a separate switch for the electronic mag?

moespeeds said:

Any disadvantage to running an impulse mag on one side, and a surefly on the other? So both sides make a spark during startup? My primary concern is to eliminate the hot start issue.

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I was advised by SureFly and E-magAir to replace the impulse mag if I was only running one EI along with a standard Slick. The impulse coupling can be problematic. There are two AD’s on the impulse couplings in the engines I was using, which could cause damage in the accessory section of the engine. If you wanted to use two SureFly mags, each powered by their own battery (two batteries in the airplane), each being charged by a single alternator, you would have adequate redundancy. The chances of loosing a battery, along with the charging capability of your alternator at the same time is very low - probably less than the chances of loosing a standard magneto or having an impulse coupling coming apart. Both batteries don’t have to be capable of starting the engine. You only need one battery for that. If you loose your alternator in flight when equipped like this, land and fix the alternator, but isolate and only run one SureFly at a time until you get on the ground. You should have more mag running time in this scenario than you have fuel on board.

Mixing mags

I have an impulse coupling on the left and a Pmag on the right. The Pmag is timed one tooth after tdc, retarded, and hasn't been an issue.
It was when I originally had it set at tdc and it kicked back once.... Now starts are instant hot or cold. I also have a Whirlwind prop.
And, like most advice, mine is worth what you paid.
danny

Kick back

I have a IO-360, 180 hp with two Sure Fly, was installed per the manual.
After a kick back I had to replace the starter and starter ring gear.
I reset the start timing for the right mag to 5* after TDC.
The Sure Fly timing can be set 5* differently with Dip Switches so both
Ignitions will now fire at the same time 25* before TDC exept when starting
the engine. This works fine for me, but it is no longer according to the IM.

Good Luck.