I just bought a car and I found out that the AFR heads on it require 3/4 inch reach spark plugs but the current plugs that it had were only 1/2 inch reach. So after pulling the heads off the car I noticed that the plug was not even in the chamber but 1/2 inch in the hole. I think this was one of the reasons that the car ran best with 30 degrees of initial timing. Has this happened to anyone else? How much better did your car run after you corrected the problem? Just would like some feedback?

 

Most people I know find out what spark plug the cylinder head requires rather than tossing in some random plug.

 

Yeah I know thats why I checked on the size after I pulled it out.