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Collected by: Guenther Eichhorn gei at cfa.harvard.edu

Question

Maybe this can generate some good info along the lines of Hot Starts... My AEIO-540 has 10:1 pistons and a 200 cm. 3-blade MT prop. I think that these two mods conspire to make mag checks miserable. The engine seems hyper- sensitive to mixture at lower RPM's, and pops and snorts a lot during mag checks. Smooths out at about 2200 RPM, but the brakes won't hold it. I've fiddled with the little idle mixture link, but the scheduling of fuel to air still doesn't seem too good.

So I wonder if fine-wire plugs might help? The engine has REM40E's; does anyone have experience with this and might REM38S plugs help? I'd just try a set, but there a little pricey for experimentation. BTW, engine and plugs have about 30 hrs. since MOH and it's been doing this since first flight. Runs fine in flight.

From: Doug Sowder DSowder@aol.com

Answers

The DR 109 has an engine very similar to the S 2B. I have flown it from Los Angeles to Sun 'n Fun. twice. The first time it had massive electrode plugs. The last time it had fine wire (expensive) plugs. The fine wire plugs did away with all of the snorting, popping and anxiety of run up/take-off time. I think it was worth the expense.

From: Dick Rihn RIHNAIRCO@aol.com

I cannot figure it out, but we have had a REALLY bad experience(s) with the platinum plugs. I had a new set of Auburns that worked great for about 200 hours in my AEIO-360s, but when we tried to run them in the AEIO-540s they started shorting out and fouling like crazy. They definitely work badly in the bottom plug holes and seem to short out with such high frequency we exchanged or tossed them in the trash. Apparently, the iridiums last forever but might demonstrate some of the same poor performance on the low end idle.

Right now I use REM38Es everywhere and have had much better experience all around. We use CHAMPION SPARK PLUGS to support the team, but would in fact buy them anyway.

Immediately after starting and until takeoff we lean the motor to almost a cut off point on the ground. Basically peak power. Try your mag checks leaned like this, and the problem may disappear altogether. By the way, you cannot detonate a motor at low power on the ground, so do not worry. This procedure keeps the plugs cleaner for sure.

From: Kurt O. Haukohl TwoWing6@ix.netcom.com

I've had the iridium plugs in my B since one month before the AWAC and have found them trouble free. I can't say that I noticed a tremendous amount of power increase, but there was some. The engine very definitely ran smoother and I think it is worth the expense. They will last longer than massives too.

From: Gerry Molidor GMolidor@aol.com

I had similar difficulties with irridium plugs. At approx 200 hrs, they began to fail through some type of internal short. Bobby (at Jackson Co., Texas) checked my plugs when I began to run very rough and found 2 bad, to my amazment, from a full set of brand new ones.

From: Bert H. Berrong vulcan11@flash.net

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Last Update: Sun Dec 17 15:42:31 2006

© Dr. Günther Eichhorn
Springer 101 Philip Drive Norwell, MA 02061 USA, Email Guenther Eichhorn