049 Glow plug conversion perfected
Imalready using a tapered tap I just wont run it all the way through. If you look at the hole in the stock head for the platnium element it is smaller than the hole in the plug for the element there. That gives it more volume which therfore reduces compression ratio. I also shaved the head .005 at a time until i dared not go any more. The starting hole size is also a big factor in thread engagement as well. The smaller the starting hole the more thread engagement you will have. I am currently using a #3 drill bit and get 85% thread engagement according to the tap and die charts If i used a smaller bit by one size i would probably get more thread angagement which equals better sealing properties.