Spark Plug wires way too long

[Monkey]

Seems like it would take the spark longer time to get to the plugs on those longer leads thus throwing the timing off
Sorry, I was just boared

[frazitl]

the long wires are there to allow jump starting the guy next to you at home built parking at KOSH?? Just remember to stay away from the spinning prop(s)...


btw, my Superior wires were just right (or maybe an inch too short if anything).

[koda2]

The manual you need to download from Slick is L1318H. It lists the harnesses from Slick and which engine they go to.

IIRC, the M4001 and the M4004 are two of the most common harnesses for Lycomings. You can order the half harness (R side or L side) but it is cheaper to buy the whole harness and then you have parts.

I had the same problem in building up an M1B and I was using a Lightspeed. I talked with a supplier and we finally figured out either the 4001 or 4004 would work, and I chose the 4004. My M1B engine adventure fell apart so I never got to see if it would have worked.

I am not sure why Lycoming said not to shorten the original-style wires because I thought you could and there are people out there who can pretty much assemble them.

I also thought that the factory certified M1B had a Lasar ignition, maybe thats why the harnesses are different???

Also, I haven't compared the routing patterns from the A1A and the M1B but they ought to be about the same. I would stick to the original pattern if you could.



Dave A.

[Beancounter]

Guys I shortened my slick harness. Verify that the fitting that attaches to the plug isn't just pressed together rather than crimped. Mine just pulled apart and I cut to the desired length and re assembled.

[az_gila]

One reason that there are two harnesses for the Lycoming 4 cylinder engines is that Lycoming has two wire layouts, with one being called an option -

[Bubblehead]

I have the Bendix dual mag system and replaced the harness a couple of years ago. The new harness was way too long even though ordered for the specific engine model I had. Someone told me a shop in Lancaster could shorten the harness for me but I never had it done. I just doubled them up and used adle clamps to secure to the engine mount.

Perhaps Walt, Mel or one of the other DFW guys know what shop I was told about.

[Airhead]

Lycoming originally told me that the wires could not be "field shortened". However I eventually talked with a Lycoming tech and he send me a pdf of Slicks harness manual L-1499B and said they could be shortened according to instructions in the manual using a tool kit sold by Slick. The manual contains a list and description of the tools involved. After a review I concluded that the tool kit would probably cost more than a new harness. Really meant for a mechanic who could use it more than once. If anyone knows of a shop that can do this work, I will place them high on my "places to fly" list.

Thanks guys for the suggestions and just as important, the humor. We can only smile at the attitude of large corporations which are too busy growing the top line to worry about the bottom line..that is the satisfied customer. Well the good side is that it just makes it easier for small companys to start and flourish. I know this first hand, its paying for my RV.

[RV6_flyer]

Originally Posted by Airhead

Lycoming originally told me that the wires could not be "field shortened". However I eventually talked with a Lycoming tech and he send me a pdf of Slicks harness manual L-1499B and said they could be shortened according to instructions in the manual using a tool kit sold by Slick.

--- snip ---

I looked at L-1499B and it calls out T200 tool kit. Been a while since I purchased a harness but $200 at Aircraft Spruce for a few tools does appear like a lot. (Aircraft Spruce had the lowest price that I could find.)

Following are photos of how my harness is routed. Been that way for 15-years. Only slight change going from Bendix to Slick mags.

















When I was doing the firewall forward, I have a Piper Pawnee a few hangar down undergoing restoration. I was able to go there and copy some items the way it was done for my installation.

[jrs14855]

The mag end on the Bendix is just a short tapered bushing that presses into the cap from the mag side. The end of the shielding is captured between the bushing and the cap. Then a rubber?? bushing slides over the end of the wire and the wire core is crimped with a special end. A piece of steel tubing machined to proper size would be fine for pressing the bushing in place. Not sure about the crimped end.