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Old 06-09-2017, 08:33 PM
BobTurner BobTurner is offline
Join Date: Dec 2011
Location: Livermore, CA
Posts: 5,443
Default IO-540/retard mag

Today I was checking out the new owner of a -10 in the presence of the builder. The plane had two toggle switches (on/off) for the mags. I asked the builder if the left mag was the retard one, and he replied that neither mag had retard points, but that was okay since both had shower of sparks. I guess he saw my odd look, because he became defensive, asked if I was an A&P. I advised the new owner to really find out what mags were there, and if they really had no retard points that there was a non-zero chance of a kick-back and broken gear teeth. What say you? Am I all wrong here?
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Old 06-09-2017, 09:32 PM
Jesse's Avatar
Jesse Jesse is offline
Join Date: May 2005
Location: X35 - Ocala, FL
Posts: 3,645

I'd be willing to bet that one is a retard mag unless it has an impulse coupling. Best option is to pull the top cowl and have a look.
Jesse Saint (Saint Aviation, Inc. - VAF Advertiser)
RV Hotel (hangar, room, car) at X35 in north FL

Commercial ASEL/S A&P/IA EAA Technical Counselor

Dynamic Prop Balancing, Prebuy Inspections, Condition Inspections, Repairs and Mods, Injector Tuning, Airframe, Engine, Panel Upgrades, Ferrying, etc.
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Old 06-09-2017, 11:13 PM
eaglen92ce eaglen92ce is offline
Join Date: Oct 2009
Location: Chandler, AZ
Posts: 166

If either mag has an impulse coupling you should be able to hear it snap when pulling the prop through by hand (mags off of course!!). That would not answer which one it was though.
Bill York
Stellar Airpark (Chandler AZ)
RV-6 N477DH
Eagle II N92CE (sold)
Hiperbipe N777HT (sold)
PA22-160 N9322D (sold)
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Old 06-10-2017, 07:24 AM
RONSIM's Avatar
RONSIM RONSIM is offline
Join Date: Feb 2008
Location: Largo, FL
Posts: 852
Default Hard starts

Our new (OH) IO 540 for the RV-10 came with retard (no impulse), and no Slickstart -- took me over a year to figure out why our starts were difficult, and even impossible, when hot. Installed Slickstart and problem went away.

RV-10 Co-built, maintained, flown (sold)
RV-8A Maintained and flown (Sold)
RV-6A Bought and Flying (N177RV), upgrades $$$
IO360, 180HP/CS, AFS 5600T, D10A, G650, G430, G327, ADS-B, VIZ385 AP
Very Happy Contributor
Based at KCLW (Clearwater, FL)
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Old 06-10-2017, 11:34 AM
Lenny Iszak's Avatar
Lenny Iszak Lenny Iszak is offline
Join Date: Sep 2008
Location: Palm City, FL
Posts: 261

My engine came from Van's in 2009 with a straight and a retard mag. Never seen a retard mag before and looking into it I figured out that I needed a SlickStart for it to start reliably. Not sure why that wasn't included in the kit or at least offered as an option. Maybe it was and I overlooked it.

Technically you can hook up a SlickStart to a straight mag using the wiring diagram intended for impulse coupled mags, but that would be bad as there will be nothing to retard the ignition. Not good.

I'm with Jesse, he most likely has a retard mag. At least I hope so
If he really has two straight mags with shower sparks, he's got a more thorough inspection to do...
Lenny Iszak
Palm City, FL
2014 RV-10, N311LZ - 450 hrs

Last edited by Lenny Iszak : 06-10-2017 at 03:59 PM. Reason: spelling
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Old 06-10-2017, 03:00 PM
awmuhs's Avatar
awmuhs awmuhs is offline
Join Date: Jun 2013
Location: Tucson, Az
Posts: 134
Default Slick start

I had same experience as RONSIM. I do not understand why there isn't more info on slick start provided with the Vans IO540 engine configuration.
Alan Muhs
Tucson, Arizona
Dues overpaid December 17, 2018
RV12 Southern Arizona Teen Aviation: wings, empennage & tail cone completed. Fuselage 90% complete, engine hung, waiting for avionics
RV10 flying since July 2014- 550 hrs as of Dec 2018
RV6A purchased and flying
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Old 06-10-2017, 06:43 PM
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MauleDriver MauleDriver is offline
Join Date: Aug 2006
Location: Lake Ridge Aero Park - Durham NC
Posts: 172

I'll add one more experience concerning the 'Vans' IO-540 and SlilckStart. I bought and had my engine delivered around 2008 but didn't hang it until 2009.

In 2010 I figured out that I needed a SlickStart unit to go along with my mags (1 was a retard). Sometime after that I discovered that a SlickStart unit has been billed as part of my engine purchase but was not shipped or otherwise included in the package! So I bought 2, got 1 and hooked it up to one mag.

So close to first flight, I didn't bother to try and go back and recover anything from Lycoming or Vans or whoever didn't ship it. I had been doing careful and thorough inventories on all shipments EXCEPT for the engine. There's a lesson in there somewhere and I'm probably not the only builder that happened to. Check your records.

Bill "at 900+ hours and happy as can be" Watson
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Old 06-11-2017, 09:55 AM
WrightsRV7 WrightsRV7 is offline
Join Date: Aug 2015
Location: Hurricane Utah
Posts: 151
Default mags with engine delivery....

Just a recent data point for a new IO-540-D4A5 purchase late in 2016. Still no impulse coupling mag, you are not billed for a high voltage kick-supply, and it is suggested to get the ~1200$ solid state voltage unt for the left mag. Left mag has the retarded option (which is starter switch activated) and the right has none (just one timing setting). I choose to install electronic ignition (with built in starter delay for lower RPM) on right side for about the same price as the voltage boost unit. Left mag was used as is with only primary timing setting used. I have really enjoyed the two toggle switch arrangement for mag check/function, push button start, feels like I am flying my twin at start up... but just half the gas and same cruise speed.... I can say hot and/or cold starts are a breeze with this set up. My kudos out to CPI who supplied my electronic ignition system. First go at starting each and every time within 20 sec. I will say, over the years though, I have watched many batteries drained to exhaustion, mostly from less than optimum hot start strategies, and yes it is a strategy, from turning on the master switch to that first turn on the starter.
Michael Wright
Dues paid 2018
RV7 built & sold, 500h of pure joy in the air: sold
RV10 slow build, 200+ hours in the air
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Old 06-11-2017, 01:29 PM
vic syracuse vic syracuse is offline
Super Moderator
Join Date: May 2005
Location: Locust Grove, GA
Posts: 2,385

Agree with the previous poster. Before spending money on a slick start you should consider an electronic ignition. Between NOT buying the Slick Start and selling the mag, your cost will be almost minimal, and the improvements are really worth it. Especially for the RV-10. It likes to fly at higher altitudes (and so will you as it is more comfortable up high) and electronic ignitions really make a difference in engine performance up high.

Vic Syracuse

Built RV-4, RV-6, 2-RV-10's, RV-7A, RV-8, Prescott Pusher, Kitfox Model II, Kitfox Speedster, Kitfox 7 Super Sport, Just Superstol, DAR, A&P/IA, EAA Tech Counselor/Flight Advisor, CFII-ASMEL/ASES
EAA Homebuilt Council Chair/member EAA BOD
Van's East Coast Representative
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