Where to route the ignition cable?

Hello builders!

I'm unsure where to rout the ignition cable for the top plugs.

Version 1: Cable straigt and a "serviceloop" outside of the baffles. The cable would be inline with the cooling airflow and hopefully do not "fludder" and crack.


Version 2: Service loop inside the baffles. Cable are quite loose and soft, so they can flap around an hit on injection lines, cooling fins and rocker shaft tube.


Both versions have pro and contra, the longer cable is maybe more servicefriendly, but need a clamp somehow to fit it.

Thanks for thinking about it and giving me a answer.

The second photo it the one I prefer and then through the rear baffle. Use Aircraft Spruce P/N M2375. I have built hundreds of Lycoming engines and always use these. On the pushrod tube just FWD of the injector line clamp, install another ADEL clamp with a P/N M2755. Just twist the clamp 90 deg so the wires point straight back.

supported at baffle

I supported the fwd lead at the side baffle with a p-clamp then through the aft baffle. the leads are zip tied in a couple of places to each other.

Will do it that way!

Thanks for your input and the numbers of the plamps! I have two of them ready for the cable of the lower plugs. Will buy two more.

I will check those two solutions and install them, but with a clamp more on the way to the rear baffle.

This is how I did it... little pieces of steel and some adel clamps:

Very nice looking Matt.
Please keep an eye on it.

My dim memory says there were occations where using the injection line Adels for additional hardware changed the natural frequency of the system and caused an engine failure. This may be the reason for the recurring Lycoming AD for confirming the Adels are per the factory locations.

The reason for AD 2011-26-04 is to prevent the fuel injector lines from braking at the brazed joint at the ends and to prevent wear at the clamp locations. Due every 100 hours. I check every time the cowl is off!

Forgot one thing! Nice engine and leads! The time spent now will pay for itself in the long run!

rzbill said:

Very nice looking Matt.
Please keep an eye on it.

My dim memory says there were occations where using the injection line Adels for additional hardware changed the natural frequency of the system and caused an engine failure. This may be the reason for the recurring Lycoming AD for confirming the Adels are per the factory locations.

Click to expand...

Hi Bill - I was aware of that AD but your note prompted me to go back and read it again. Here is a link to AD 2011-26-04, and here is a link to Lycoming MSB 342 which the AD references. At first glance I don't actually see anything in there that would prevent someone from adding extra hardware to the existing clamping locations as I did... the AD and MSB just want you to make sure that your fuel injector lines are indeed clamped securely and supported at the specified locations. Having said that, it's so easy to just add another separate set of adel clamps there that I might go back and do it just for peace of mind. Thanks for the heads-up.

- Matt

I re-did these support brackets to not use the same clamps that hold the fuel injection lines. Not as nice looking, but increased peace of mind. I suspect it would not have been a problem, but better safe than sorry.



mcb