Ignition weak points?

Here is what I have. 15.25/1 compression methanol fueled , 550 cubic inch with 572=13 heads. I have 8 mm morose wires, a stock cap and rotor, Ngk5672-9 plugs gapped at .025. On the dyno the motor was miss firing. We leaned it out some and the miss fire went away. We only had to lean it out between five and ten percent to get a good clean pull on the dyno. So knowing that it didn't take an extremely rich mixture to start miss firing, my question is,, what is the weakest link? The ignition is a new MSD7531 programmable 7 and when Iusing a test box, really sounds good. So what may be the weakest link in my package? After proper jetting, it made 982 hp, so power is good. I am just concerned about being so close to miss fire.

I’ve had to go down to .018 several times to get them to hit. I think some guys get way too excited about big plug gaps. I ran my Super Mag III (which was almost 5 amps) at .018 to make it hit above 8,000. If I wanted to shift at 6500 I could open the gap to .030ish and that’s WIDE for a mag.

Thanks for the reply. I wonder if part of the problem might be the small stock cap and rotor? I would hope the digital 7 has enough energy to cause trouble there if compression and fuel create too much resistance?

Maybe doesnt need the projected tip?... I've always used 5671's in wedges

Does the engine have a crank trigger? And if it does, did you phase the distributor? The reason I ask is it usually has to be pig rich to miss and if the rotor isn't phased it doesn't take much. Also, if it doesn't have a crank trigger, disregard everything I said. LOL

Did you have 02's and or exhaust temp sensors on the engine during the pulls? Others may be better at it but I have always had a hard time reading plugs in an alcohol engine. And you are right normally methanol has a broader flammability range than gasoline. you said you leaned it a little and the missfire went away, did you try and lean it more? I try and lean until the exhaust temps start to rise.

Firecore wires. Good head grounds. Tight plug gap. MSD dizzy.
I had to do all the above to fix my ignition when I turned up the boost.

My next step is pulling the 7531 and going to the Pro 600 coil on plug. Hope to convert to alcy at the same time.

I have a crank trigger, and will double check the rotor to cap index at 34* where I run it. I will also reduce plug gap to about .022 to see if there is any difference.
On the MSD distributor, guessing that is about $400, and moving to coil on plug would be nice but I assume costly compared to just upgrading a distributor. Does the MSD distributor clear the 440-1 and 572-13 heads?
On rotor phasing, my thought is to make sure it is at least dead center rotor tip to cap contact, never retarded, where a crossfire could occur by jumping from cylinder five to seven. I wonder if that had ever need an issue, and assume it would really raise he!! With the motor, causing huge stress on the crank at the fourth main area.

We leaned it out at max torque area till we saw no improvement, then had to add fuel back in at hi rpm for max power by reducing the secondary bypass pill. The plugs ( NGK5672=9) were easy to read, timing looked good on the ground strap, and the base metal plating was scorched about half way around, which I understand to be about right. Individual Exhaust Temps were used for base line pulls, then my car headers to get the tuneup spot on.

I was going to post the cap and rotor as weak points yesterday but got sidetracked Greg. Also don't be surprised if you have to put some fuel in it once it's in the car. My engine was pig fat on the dyno, leaned it out and then had to put most of it back in at the track.

Greg, the MSD distributor will clear your INDY heads. Clearance has more to do with which valve covers you run. I had INDY valve covers in the past, and now have Trick Flow covers on my engine. No issues with either.

Have you tried a -8 plug. I have done this on 2 alky motors per APD recommendation.