I am going over my 340 and wanted to get the best pugs and the correct gap for my set up. This is a 1969 340 with factory TA heads and forged nominal 10.5:1 pistons (my best guess is between 10 and 9.5 to 1 actual compression). The car is street driven with very few passes down the 1/4 mile. The ignition set up is an old analog MSD 6A box and a MSD billet distributor with a Flamethrower conventional shaped coil. The engine is running well on Champion RN14YC plugs, but it is time to replace them and there is a lot of new technology out there. The main goal is rock solid dependability - can't have things screwing up hundreds of miles from home. The RN14YC plugs were gapped at .045.
Looking for replacement plug recommendations and gap recommendations with the MSD set up.
