@Zed Head Great article

5 hours ago, Zed Head said:

That is a "colder" than spec spark plug. Might be why the electrode on 1, 2, and 5 are dirty. The white ash on 3, 4, and 6 looks pretty good, but still on the cold side.

Have you adjusted the valve lash? It looks like you have some cylinder imbalance.

https://www.ngk.com.au/technical_info/heat-range/

I adjusted the valves about a year and a half ago, but that's a good point - I'll give it a look and report back.

Regarding the spark plugs, I can't seem to find any bpr6es on amazon for the 78 head thread. Would bpr5es work or would that be too hot a plug?

Interesting article - thanks!

EDIT: I believe we ended up going with colder spark plugs since we're running the engine learner than usual (14.7 cruise) to guard against pinging.

EDIT 2: I just confirmed all of the valves are still in-spec

Edited 7 hours ago7 hr by chaseincats