I am running a 426 wedge with factory Cross Ram. Mopar Performance steel replacement heads (MW). 12.2:1, with a large roller cam. .680" or so. I have run Autolite 72's in this car for years. I also run an MSD 6AL with a blaster coil. I typically gap the plugs at .035. I have two questions:

1. Should I run a different plug?

2. Am I gapping them correctly?

Thanks in advance for any help you can give. I'm trying to hit a Test and Tune this weekend for the first time in three years. Can't wait to get the old girl out, but am prepared for issues from sitting.

Usually with the MSD you can open the gap a little,try .045

I like NGK ? And I gap my sb with 6al and MSD SS coil at .046.

Thank you for the responses. I've tried .045, but the ignition didn't seem to like it. Do you think the Autolite R72's are ok?

I run Auto-Lite's and NGK's in mine and both work good. I dont notice any et difference and both look about the same color when I check them which is about every 6 months. I gap mine at .035 but I use the MP orange box and an Acell coil. Ron

Exactly, I stopped the gap em wider w/msd ign. stuff years ago and run my NGK`s at .035.........

Thanks again for all the help.

Guess I'm out of date but.. In the 70s with my high comp. max I ran the MSD 7c with j-7s ,yea lawn mower plugs, no extended tip on those baby's,gapped at 55'. Hookers where a [censored] on number 4-6-8 and the short plug worked great, had three different wrenches to remove, used same plugs two years running then changed for the heck of it, they where cheap, of course we had 260 Sunoco then. Thinking back I would love to have that 64 on the street now.

The MSD and matching coil can handle the bigger gaps and secondary voltage... but maybe not the rest of the system for very long (cap, rotor, wires). I gap mine at .040" and think .035" would be OK also.

With any multiple discharge system which MSD used in a natural aspirated engines the wider gap allows a larger spark and better fuel burn.Usually if you have an issue with the plugs at a wider gap then you may have a voltage problem.

Drain all the old gas out and get all new race fuel, on the gap the wider the gap the more voltage the coil will have to build up to jump the gap, the better it will idle when cold and hot The 6AL may be okay, I would set the gap at .045 and see how it runs, if it starts to miss in the upper RPM, above 6000 RPM then set it at .035 and see if that makes the miss go away I have race several different M.W. motors in several different cars and classes,I always used the MSD race boxes from the old 404B and 404C to the current 7AL2, never treid the 6 series boxes so no real help on them, sorry I would buy two sets of plugs,# 72 and 73 and try both set at the same gap and see which one you like the best after using both sets M.W. motors rock

Unfortunately we hurt the rear...and lost oil pressure. Looks like it will sit for some time. Thanks for all the assistance. UGH!!!