4.2 Series 1 Spark Plug Thread Tap

gmunro · Post by **gmunro** » Thu Sep 10, 2015 11:52 am

Hi. Can someone please advise me what size of tap I should use to run down the spark plug thread on my 4.2 Series 1 head? Should the tap be imperial or are they all metric? Where can I obtain such a tap?

Any assistance will be much appreciated.

Kind regards,

George

Moeregaard · Post by **Moeregaard** » Thu Sep 10, 2015 12:33 pm

The correct thread is 14mm X 1.25mm, and any good tool supplier should be able to provide the tap. Re-tapping the threads might buy you some time, but if they're damaged the only permanent solution is to install inserts (Helicoil, etc.).

gmunro · Post by **gmunro** » Thu Sep 10, 2015 12:44 pm

Thanks Mark for the advice.

The threads are not damaged but when the head was painted, I can see some paint has gone into the spark plug holes. I just want to "clean" the threads up a bit.

Your advice is much appreciated.

Kindest regards,

George

abowie · Post by **abowie** » Thu Sep 10, 2015 9:28 pm

One trick would be to cut a couple of lengthwise grooves in the thread of an old plug with a Dremel. Then grease it (to catch the swarf) and install then remove it.

gmunro · Post by **gmunro** » Fri Sep 11, 2015 7:40 am

Hi Andrew,

Thanks for the idea ...... I'll give it a try.

Yours aye,

George

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