Sparkplug reach

[Dodgeboy]

I was going thru my used sparkplugs and noticed I've been using 2 different reach lengths. 3/8" and 3/4". I have a '71 383 with 2406516 cylinder heads (1964-67). I believe the machine shop installed Champion RN9YC plugs (3/4 reach) and I have used Autolite 56 (3/4 reach) and currently have Champion RJ12YC (3/8 reach) plugs in the car. Reading the plugs the autolites were the nicest but they would be equal to Champ. RJ14YC in heat range but I didn't use them for very long. However my cars always ran rich and I'm finally tuning it myself. Anybody see any issues using a longer reach plug (RN9YC) instead of the normal RJ12YC? I don't have any interferance issues as something would have broke by now (piston/plug).

 

[Daves69]

...........I don't have any interferance issues as something would have broke by now (piston/plug).

IMO, use the correct plug "reach" for the head. Run the hotter J-14y if you need to deter fouling. Fix the real issue causing the fouling.