Mick's 70 Lowlight

Another small step towards the end goal. I made up a small calliper to measure the thickness of the cylinder head at the second plug location so that I could select the correct length spark plugs. The second plug is a smaller 10mm plug. Next task on the agenda is to make up a spark plug indexing tool. The idea behind spark plug indexing is to face the electrode bridge away from the chamber to aid in flame travel. Ideally electrode gap wants to point towards the densest part of the charge. The location of the charge is determined by reading the spark ignition point on the plugs (small clean area on the electrode). Alternatively facing the gap towards the exhaust valve is stated to help improve the burn.

This may be taking things to extremes but as I am running twin plugs I want to make sure that the flame fronts from each plug travel in the same direction and at the same rate. If one is obscured by the electrode bridge it could result in an uneven burn.

I also want to get into the habit of indexing the plugs as the next incarnation of development is to run a squish piston design which will totally enclose the plug except for a very small burn chamber. In this case indexing the plugs will be very important.