Hello forum members.
I have an iron head from a B33. I noticed it has a helicoil repair to the spark plug hole. I would like to get rid of the helicoil, and re-tap the hole to suit a larger spark plug. Any advise with regard the most suitable spark plug to use???
Thanks keith
In all my restorations, I have never had to use a helicoil.
My idea is that they are a good fix for a thread that does not get taken apart very often, but a spark plug hole would be prone to failure.
Can you explain an insert.
Thanks keith
My experience of helicoils in plug holes is they are either a perfectly satisfactory repair or they become a complete pain & can end up turning out of position & ive also read that the stainless helicoils (particularly on alloy heads) can change the way heat is transfered from the plug & can also also not always cover the thread all the way sometimes allowing some of the plugs thread to be exposed cylinder side of the helicoil.
Inserts I think are better as they can often be bought correct length & have a system of locking into place at both ends & come in a choice of materials. I have one ally head bike with an aluminium insert in the plug hole. .. but .. For the insert to have the "locked in place" function it needs a lip at the top, that means the plug seats slightly further out unless you machine a recess first.
