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TR6 What size tap for TR6 spark plug?

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I

ichthos

Darth Vader
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I had my cylinder head cleaned, and while it is off, I thought it would be a good idea to run a tap through the spark plug threads. Can someone tell me what size tap to use?

Thanks, Kevin
 
Kevin,

If you have a set of taps and dies;
find which die fits the threads on your plugs
and then use the matching tap for your plug holes.

I would suggest caution since the plug threads
have probably had plugs in and out a few hundred
times over the past 40 years. You don't want to
go removing more metal from the threads if you
can avoid it.

Just my 2 pence worth and I'm the tap/die everything
guy. I would leave well enough alone.

dale(Tinster)
 
I agree with Dale; if you don't have problems getting the plugs in and out then leave it alone.
 
Kevin, Sears or almost any automotive supplier sells a special tap specifically for chasing spark plug threads. I strongly recommend using it rather than an ordinary hand tap, as it greatly reduces the chances of damaging your head.
https://www.sjdiscounttools.com/kdt3379.html

The threads are unusual anyway (specifically for spark plugs) and not usually found in sets. Metric, M14 x 1.25 as I recall (but don't quote me).
 
Kevin, as stated by others, I would leave them be unless there is a problem.
 
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