@kwlf, aircraft cylinder heads have steel thread inserts for the spark plug threads so the issues with thread galling, wearing and fatigue are mitigated relative to an aluminum automotive head with no insert.
Helicoils were apparently developed for this specific factory installed aircraft application in the 1930s, before they were used for thread repair. I’m not sure what kind of insert Lycoming and Continental use nowadays.
Don’t use a wire brush to clean plugs. I just clean out the lead balls etc with a pick occasionally and leave it at that.
Przemek wrote:
I’m wondering, why lycoming says in their SI 1042AH says DO NOT use a graphite-based compound. ?
Tempest compound designed for spark plugs is graphite based…
I thought the reason was many wrongly applied the graphite lube i.e. excessive amount of it that causes it to flow over the electrodes and short them.
