Spark Plug wires way too long

[jrs14855]

Years ago when Bendix was manufactured in Sidney NY, I had the tools to form the mag ends. I customised the harness to eliminate the exess wire. The tools are long gone and would only work on the Bendix harness. This is not rocket science if one wanted to build the proper tools to shorten the wires. It should definitely be done on the mag end.

[flyboy1963]

Bob,
it's quite evident that Van's has shipped the wrong engine mount.
You'll want to start over with the one that's 3' longer, or those wires are gonna get all chewed up in the prop!!!

( sorry, someone had to say it!)

Hey, while I'm here being a jerk!......anyone able to tell us where NOT to route them? with 50 zillion volts going thru, I'd think you should not run them along the engine mount, but keep them stood off an inch from each other, accessory wiring and such? I gotta say that keeping them high, clear and clean can't be a bad thing!

[Wayne Gillispie]

They make them all for our -540's. I had no excess to front cylinders.

I definitely would not put the excess over cylinders, creating a restriction to airflow.

The wires are insulated and if protected from chaffing/abrasion will not short to your engine mount.

[aerhed]

Ideally, you should treat your ignition leads just like control cables and exhausts. In other words, they should only be attached to the engine and not to motor mounts or structures. Every time you anchor something off-engine you create a node. You'll have resulting vibrations of varying amplitude and frequency on each side. Electrical wires and stuff have to anchor somewhere and those are frequent problem areas. Very common on production planes to have over length harnesses and usually they are bundled between the mags and ty-rapped. I see a lot of guys on the homebuilts who try to route by the shortest distance. Many hang their leads off adels dangling from the rocker cover. I hate that for a couple reasons. When I've got enough length I prefer to route the bottom leads from above the rockers and pick up the baffle bolts in the cylinder head. I try to leave the rocker covers "unadorned". If you do it right, you're minimizing vibrations, chafing, exhaust cooking, and also avoiding oil soakage.

[Airhead]

My routing was according to the Lycoming Harness Attach Dwg No. LD-4313-9 (see below), which came with the engine, but also was the first item Lycoming sent me after I contacted them with my complaint. I assured them I had used their drawing. Vans also includes a harness wiring diagram in the FWF plans. Virtually no significant difference, especially for the top plugs.

However, all that aside, it remains that no matter what your routing, you won't use an additional 2 feet of wire. Why bother sending us two diagrams, neither of which work!

[6 Gun]

You have plenty of time to mark the wires at the right lenth and send them back to the factory to have the ends shortened and send a note to stop sending out **** like that.

[Wayne Gillispie]

You will never see it in flight and what few ounces most of you save will more than make up with in gadgets/fancy interior anyway. Spend money and time replacing that 3003 aluminum fuel and brake lines with 5052.

[Vlad]

The longer the wires the higher spark velocity is

[jrdavis060447]

I purchased the same YIO-360-M1B from Van?s aircraft for my RV-7A and faced the same problem with the magneto harness. I had excess length in the 20 inch range. I solved the problem by purchasing a new harness from aircraft spruce. The M4001 harness fits correctly right out of the Slick box. In this case throwing money at the problem worked best for me.

[jrs14855]

I took a wire out of a Bendix mag harness at the mag end. Really pretty simple but it appears the crimped on end would be a special item. The old ends could probably be drilled out and the shortened wire soldered in place.