I somehow managed to put together a high compression engine, and run it, with no issues, until now. Sunday was time for its first spark plug change, and this time, I was not so lucky. Several plugs were closed up nearly all the way, by making contact with the pistons. Do I need to break down and by a bulk pack of plugs, and keep swapping them until I get lucky, or, do conical seat 18mm spark plug indexing washers exist? My search says they either no longer exist, or never did. Do I adapt out to 14mm? That's a thing that I have seen done. The adapters are $6ea. They, alone, might be enough to fix this. My question then would be, what plug, at 14mm conical, is the equivalent of an Autolite 46? Anyone have any insights on this?