Tuesday I installed a CDI conversion on my Mac engine. This is Rick Whittridge's magneto conversion. I bought it from one of our chapter members who decided not to use it.
The installation was straightforward, and everything went according to the directions. I had also spoken to Rick on the phone, and he was very helpful.
All of the internals in the mag housing are finely machined, and the CDI is potted to protect against vibration.
I mounted the coils on the top of my upper engine mount, taking care to leave clearance between the prerotator cable and the pushrod tubes. The CDI unit mounts between the mag housing and the upper engine mount. And the mag housing goes...well it goes where the old mag went.
I am using Champion D-9 (509) plugs from the local carquest @ $2.24 a piece vs. $15 a plug for reconditioned fine wire aircraft plugs, and stainless core 7mm ignition wires with 90º boots on the plugs and straight boots into the coils. The plugs are gapped @ .030".
Timing was a snap using Rick's instructions too. I set it to 21º BTDC.
After wiring the switch, and tidying up the wires, we rolled it out side and it fired on the 3rd pull of the prop. No stumbling, no spitting, it just started. Several times.
Yesterday, I took it up for a late afternoon flight and it ran like a top. Same thing for today. The highest CHT that I saw with the retarded timing is right at 400º on climbout, and that drops quickly on power reduction.
The idle is smoother and I was able to reduce the idle speed a little, but since my TinyTach bit the dust I'm not sure of the RPM's.
I'll attach a couple of pictures of the installation.
The installation was straightforward, and everything went according to the directions. I had also spoken to Rick on the phone, and he was very helpful.
All of the internals in the mag housing are finely machined, and the CDI is potted to protect against vibration.
I mounted the coils on the top of my upper engine mount, taking care to leave clearance between the prerotator cable and the pushrod tubes. The CDI unit mounts between the mag housing and the upper engine mount. And the mag housing goes...well it goes where the old mag went.
I am using Champion D-9 (509) plugs from the local carquest @ $2.24 a piece vs. $15 a plug for reconditioned fine wire aircraft plugs, and stainless core 7mm ignition wires with 90º boots on the plugs and straight boots into the coils. The plugs are gapped @ .030".
Timing was a snap using Rick's instructions too. I set it to 21º BTDC.
After wiring the switch, and tidying up the wires, we rolled it out side and it fired on the 3rd pull of the prop. No stumbling, no spitting, it just started. Several times.
Yesterday, I took it up for a late afternoon flight and it ran like a top. Same thing for today. The highest CHT that I saw with the retarded timing is right at 400º on climbout, and that drops quickly on power reduction.
The idle is smoother and I was able to reduce the idle speed a little, but since my TinyTach bit the dust I'm not sure of the RPM's.
I'll attach a couple of pictures of the installation.