Spark Plug Indexing

[Steve Williams]

Nelson,

I assume you have a Chevrolet small block. What I found out concerning indexing and plugs is real simple. There is a small difference in power when used with timing change. The plug can be modified and combined with indexing a little more can be had. I tried different types of plugs. ground strap designs and gaps. Some of the plugs that people are/were paying big money for were absolute junk. One particular plug actually made less power by almost 10hp and it was the rage for about two years. Until word got out about how cheap they were. I modify my plugs ground strap and index all mine. I also use plugs that are not as expensive as many out there, but have good quality. As far as printed test data, I am sure it is out there in some publication. Indexing for clearance is something that many aluminum rod engines should do to avoid possibly nicking a plug.