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#1 4.2 Series 1 Spark Plug Thread Tap
Posted: Thu Sep 10, 2015 11:52 am
by gmunro
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
#2
Posted: Thu Sep 10, 2015 12:33 pm
by Moeregaard
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.).
#3 4.2 Series 1 Spark Plug Tap
Posted: Thu Sep 10, 2015 12:44 pm
by gmunro
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
#4
Posted: Thu Sep 10, 2015 9:28 pm
by abowie
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.
#5 Series 1 4.2 spark plug thread tap
Posted: Fri Sep 11, 2015 7:40 am
by gmunro
Hi Andrew,
Thanks for the idea ...... I'll give it a try.
Yours aye,
George