does anybody do such a thing I wont to go and put 12mm plugs in some old heads but of cause they only have 14mm plug holes so was wondering if someone has made a adaptor for this, must be alloy so it can be welded in
cheers

u will find another problem in the 12 mm plugs have a longer reach so they will protrude into the chamber

what wrong with 14mm plugs ??

12mm are cheaper.

forget about adapter just weld the hole and drill to suit. while you at it weld above the inlet ports, remodel the chamber, replace the seats, valves and guides, cut for dual springs, etc.

You forgot 'Machine out for big bore kit' and 'Open up ports for 48 IDAs' etc.

the main reason for it is so the spark plug is up just that lil higher away from the inlet valve so you lessen the chance of the dreaded crack or should I not worry about it

Don't worry about it

That's easy for you to say, Daimo.

yep don't worry about it

new heads will be cheaper in the long run

if there that cheap where do i get them must be for 92 mm bore as well with the same valve 40mm inlet any suggestions