I posted this up on the evil forum, but got literally no responses, so I thought Id throw it up here for the experts to see https://www.nopistons.com/forums/pub...IR#>/smile.gif



Ive spent a few hours searching the forum for some cross reference information on various heat ranges of spark plugs. I thought I remembered seeing a thread a year or two ago that gave a listing of a few different part numbers for US plugs that would interchange, but I wasnt able to find it.



I DID, however, manage to find a nice little chart of cross references of NGK, Autolite, AC Delco, and Champion race plugs here http://www.dragstuff.com/techarticle



I used this site http://www.sparkplugs.com/ to get the thread pitch and heat range of the different plugs in order to see which matched up to the OEM plugs.



The problem Ive run into is that all of the plugs listed on this site with a descent heat range have a 19mm reach, while the OEM sparkers have a ~21.5mm reach. I dont know if this difference has anything to do with the OEMs being the flat, 4 electrode type and the race plugs being a overhead electrode (that would have to be cut and bent to side fire to work)? 2.5mm seems like an awful lot when it comes to something like this. Am I wrong?



Alex

that might be good for the trailings. i have heard its better to put the tip of the plug as close as you can to the rotor housing surface

EDIT**

The first link is wrong.

Here is the correct link:



http://www.dragstuff.com/techarticles/spar...-reference.html

would make sense if you are trying to squeeze every last fraction of compression ratio out of hte engine. Plus a more exposed spark plug will have better access to the fuel air mixture to ignite it.

I wasnt sure if the fact that the shorter "racing" spark plug with the 19mm reach would have actually be close to the same over all length when you consider that the ground post actually sticks out past the body of the plug. I need to spend $2.50 and experiment, but I dont have a spare housing up here.