Hello,
  From what I remember, the Merlin plugs and inserts that fit the AP Wasp will also fit Cox engines? I currently run the adapters and Nelson plugs (from kitting it together) in my Cox engines. I find they give an extra thousand revs over Cox heads.
  I recently heard that Mr Nelson is retiring, does that mean the Nelson plugs will become obsolete? Will the Merlin plugs and adapters give the same sort of gain as the Nelson plugs, assuming they fit Cox engines?
  Being a bit of a cheapskate 3 merlin plugs and adapter are about $13 and the adapters for the Nelson heads are around $12. Is it a matter of you get what you pay for, or are the Merlin plugs just as good?

Regards,

Andrew.

Thank you Kenneth,
  I wasn't sure if I remembered correctly!  I would guess that for ordinary lowly Cox engines maybe 4 or 5 headgaskets would be overkill?  I have several Galbreath head adapters, do I need to stock up on Nelson plugs? Or are there other alternatives out there? Mind you, I have yet to blow a Nelson plug in any of my Cox engines including TDs. So maybe my small stach will see me out!

Thanks,

Andrew.

Not trying to hi-jack this thread, but I too have used the Nelson heads and if I put 2 -3 shims under the head, I could not keep it tight.  After every run, it would be loose.  Only one gasket it would stay tight, but erratic runs.  Any ideas?

John

Hello John,
I can confirm Paul's observations, Heat the gaskets up to near red heat and let them cool all by themselves. They have become workhardened by the act of compressing them, heating them makes them go soft again.

Andrew.