Change from aircraft to automotive plugs

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Web Foot
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Change from aircraft to automotive plugs

Post by Web Foot » Sun Feb 21, 2016 10:30 am

I currently have aircraft plugs and want to change over to automotive plugs. What plugs and gap is recommended for a 0470?

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glades cat
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Re: Change from aircraft to automotive plugs

Post by glades cat » Sun Feb 21, 2016 6:34 pm

Champion D-16
Autolite 386
NGK AB-6
"Leave a legacy...Preserve the irreplaceable"
12' x 7' sled built by Scorpion, Cont. O-470-K, 72" Whisper Tip
Rigged by Gladescat & sons in 2009

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Web Foot
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Re: Change from aircraft to automotive plugs

Post by Web Foot » Sun Feb 21, 2016 6:52 pm

Cool. I'm going to be changing them out this coming weekend. Now I just need to order the wires tomorrow.

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GeeLeDouche
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Re: Change from aircraft to automotive plugs

Post by GeeLeDouche » Tue Feb 23, 2016 11:43 am

I used the Autolite 386 in my 470 gapped at .020 They seemed to work well. You can make your own wires.. I think I used the eccel universal 8mm and cut them to length and soldered them into the mags.
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GMAC 76
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Re: Change from aircraft to automotive plugs

Post by GMAC 76 » Tue Feb 23, 2016 1:59 pm

if you have the stranded 7mm aircraft wires you can put automotive terminals and boots on the spark plug end and keep the aircraft wiring harness intact....makes a nice set!!.....the NGK AB-6 is a good plug gapped at .022-.024

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Web Foot
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Re: Change from aircraft to automotive plugs

Post by Web Foot » Wed Feb 24, 2016 3:31 pm

Thank you gentlemen. I will have new plug wires tomorrow. I ordered them from classic airboats. I also bought the NGK AB-6 plugs.

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Planeguy
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Re: Change from aircraft to automotive plugs

Post by Planeguy » Thu Feb 25, 2016 10:06 pm

Other than cost, is there an advantage to changing to automotive plugs?

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lbdb1a
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Re: Change from aircraft to automotive plugs

Post by lbdb1a » Thu Feb 25, 2016 10:38 pm

Check out this link on my change to "Iridium Sparkplugs in a 0520" on the forum.

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Re: Change from aircraft to automotive plugs

Post by Hardtail » Thu Feb 25, 2016 10:43 pm

Planeguy wrote:Other than cost, is there an advantage to changing to automotive plugs?
I think the main advantage is that you only need one tool to change the plugs when they get fouled in the marsh, and not needing to unscrew the cap off the plug which might get seize up from being out in the open, unlike the automotive type, and then the cost is a factor, more practical to being able to carry spare automotive plugs which also can be shared if someone needs JMO

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jopete
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Re: Change from aircraft to automotive plugs

Post by jopete » Thu Feb 25, 2016 11:54 pm

just about any country gas station has champion D-16's.

on my GPU i gap them at .025''

Gary S
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Re: Change from aircraft to automotive plugs

Post by Gary S » Fri Feb 26, 2016 6:38 am

3.00 for automotive. 30.00 for aircraft. Aircraft is a better plug but you can get 10 sets of automotive to one set of aircraft.

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Planeguy
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Re: Change from aircraft to automotive plugs

Post by Planeguy » Sat Feb 27, 2016 7:38 am

Availability and being able to share make sense to me. It is always good to have readily available spares.

Most problems of leads seizing on the plug will be self induced. They only get torqued to about 100 in lbs (8 ft lbs). Most people not regularly using a torque wrench to develop a feel for it WILL over torque the leads and under torque the plugs which is always "fun" to undo.

I don't see the tool issue. If the leads require a 7/8 inch wrench then the same socket used to removed the plug could be modified to be used to remove the lead by cutting a slot in it (or buy a sensor socket). I use a flare nut crowsfoot on some hard to reach applications for the plug and lead. If the leads require a 3/4 inch then, yeah, a second tool would be needed but an adjustable (Crescent) would do both sizes plus cover nearly any other size on the boat you may need. Having another tool handy to keep the lead from twisting while securing it to the plug is a good idea too (wrench or pliers).

Anyone have info on longevity? Aircraft plugs in an aircraft are good for about 400 hours, longer if properly maintained. I flew an IO-520 four hundred hours before the plugs had eroded enough I couldn't get the engine to start (BTW... letting the gap get that big is hard on the points too).

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getitdone
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Re: Change from aircraft to automotive plugs

Post by getitdone » Sat Feb 27, 2016 9:47 am

I use the aircraft plugs in my new 540 which have 175 Hours on them now and have had way less problems with them. Of course I check and clean them every 50 hours and do 25 hour oil changes. I did run the champion D-16's in it for a short time and really didn't notice any performance difference when I changed over to aircraft plugs and aircraft wires. In my old 540 I ran the Autolite 386,s and would have to clean them more often even with a newer top end. Personally I will run the aircraft plugs and wires even though they cost more. What's another $300-$500 when your spending $10k plus for an engine that was designed for them.
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Re: Change from aircraft to automotive plugs

Post by chuckitt@earthlink.net » Sat Feb 27, 2016 12:10 pm

Spark Plug gap as a general rule is based on coil output. If the magneto has a coil that puts out 18,000 to 20,000 volts then set the gap to .018 to .020. Most GM HEI Dist. had 35,000 Volt coils and required the gap to be .035. .001 gap for every 1000 Volts.
Too much gap on the plug will cause more voltage drop across the gap. When this resistance causes a voltage drop, currant increases and the electrode will get hotter and the coil will get hotter. Parts want last as long.

Thanks, Chuck

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