Ben Allison

I want to use a tap to clean the spark plug threads in the head, as I suspect that a spark plug may not be seating fully. Is there a trick to doing this without getting it into the combustion chamber?

I was thinking of using a big magnet to magnetize the tap and then I remembered that aluminum won't stick to it =(

-Ben Allison

Garth S

Take a good look at the threads first, and be sure this is what you need to do: there may be a crust built up on the flat sealing surface at the top of the hole. If you do go after the threads, a 'chaser' is less agressive than a tap, more appropiate for the job, and is much more forgiving of technique .
Use a heavy oil on the thread chaser or tap - the oil will retain almost all chips, etc. if any arise: As a new thread isn't being cut, a very small amount of material should be liberated. Compressed air blown in past the hole will successfully jet anything left outwards and back into one's face - duck!

Chris

Go to your local parts store, they sell a tool specially for this purpose, I used one on my 928. Has very wide flutes for collecting debris.

As Garth said use some grease and you will be fine.

Chris

tresamore

I have done this using thick axle grease on a 4 flute tap. Four flutes holds more grease to hold chips.