ECI cylinders, Auto plugs, and Pmag question.

Hello group,
I am using ECI experimental tapered barrel cylinders on my O-320 engine rebuild. They are equipped with auto plug (14mm) plug holes, and I will use Pmags for ignition. I am curious as to which spark plug number I should start with. Hard to accurately measure the plug reach for this application, and as of yet, I have been unable to verify the reach reading all of the info from ECI that I have found. Any suggestions??

Thanks so much,
Chris

I am using BR8EIX Iridium plugs. I just switched from BR8ES. The Iridium's are $8/each compared to about $2 for the others. Still I think the Iridium's are a good choice. My BR8ES were showing a bit of deteriorating after 100 hours.

Auto Plugs

I have had good luck with Denso W27ESR-U for the last 1500 hours. Cost less than $2 each. Here is a handy link: http://www.clubplug.net/denso_ngk.html

I use IK27 with my LSI, but without the adapters do the heads still use the long reach plugs?

Okay, today was my second flight and second attempt to confirm performance results.

I switched from BR8ES to BR8EIX plugs and on my first flight I noticed that the engine leaned to PK with no roughness.

Today's flight I wanted to see if that was a fluke or if I could repeat it. Previously at PK EGT the engine would run very rough and you would have to be deaf to continue without enriching the mixture. It was uncomfortable rough. Today I leaned to PK and the only indication was that the SkyView showed PK and the RPM began to drop off. As I continued to lean the "PK" changed to LOP and I was able to lean to 50 degrees LOP (probably could have gone further). Other indications were; a drop in CHT and EGTs as well as a balancing of all the cylinders. The engine continued to run smooth and I repeated the results at various power settings from 40-65%. I used 1/2 to 3/4 carb heat and no carb heat. Carb heat did seem to help balance things.