Cold/Loosing Spark Plug Fire on Cylinders-Blown Alcohol Hemi

We are still working our way up to a tune-up for a blown alcohol hemi Promod combination. The problems started at about 50#s boost and now at 55#s boost, one or two cylinders will drop or run so cool, no power is being made on them. 44 amp MSD mag, good points box, Red MSD coil just tested, new MSD gray boot wires, new MSD coil wire, plugs gapped at .014, heads grounded per MSD instructions, Power Grid Controller, all new wiring on the ignition.
One or two plugs/cylinders will drop and not recover during the run. Idle temperature and EGT look good until full boost at launch. The season is getting short now and we need some good runs/data before Winter, so any help or suggestions will be appreciated-THANKS!!!!!

 

Carbon Tracking on the Plugs and Cap

I should have added earlier that the spark plugs are carbon tracking down the sides and also the cap has carbon tracks on it too. It is the large cap and rotor phasing is good and the same that I ran the last 6 years, but at 44#s of boost with a roots blower-THANKS!

 

Carbon Tracking down the outside of the plug

Mike, new MSD 8.5 wires, a complete set of new wires for every 2 runs with a new coil wire and the same thing, carbon tracks down the outside of the porcelain part of the plug. They are factory MSD Hemi wire sets (with the gray spark plug end boots, not black) and I put the mag cap ends on and have them correct. Even a new mag cap is carbon tracking too. Any ideas would be appreciated-THANKS! Jim

 

gap

I know some ADRL cars that run the gap at .009. I've been running at .011.

 

I would try .009" right away (and be sure it is .009") and be absolutely sure you are grounded head to head to coil neg.

 

THANK YOU for the help!

To Mike and all racers/builders/owners that are trying to help. I have gotten the silicone grease, and even made a gray MSD type boot spacer (1/8") to take up the extra space showing on the plug when the boot is on. I have not run the gap any tighter than .014 yet, but one of the faster ADRL drivers told me yesterday they are running .010 now. I do run a crank trigger and made a cap to phase with all looks good with the big cap and never any problems until more boost. I will report back when we do get it fixed and maybe it can save some lost runs like I have had. The heads are grounded the coil negative side and all seems tight and good there too. This started with a second set of wires within 5 passes too and new coil wires and new plugs each pass-THANKS again for all of the help and advice! Jim

 

The only time I have seen something like this was when the mag and mag drive had bent shafts ------------ it doesn't take much and the mag in this case was deemed ok by MSD --- Bob Wyman found the problem ------

 

Is it always the same cylinders or is it random? What plugs are you running? How do the bad plugs look in general, anything weird about them when you pull them? Have you ohm checked some of the "bad" plug wires? Have you ohm checked some of the "bad" plugs?

 

Mike, when I read someones post who has a problem and needs help , I try to look at what they supply for info and WHAT they don't supply or think is important----

I'm not debating your points at all , what I was adding to this discussion was that I saw a N T/F car just two months ago that had a 44 mag--- it would idle fine -- under a load it would drop holes almost every other spark pulse, on the racepack readout .

The mag and drive was sent out to Bob, it was determined the shaft was bent, it was fixed ---------------it runs fine now .

If I knew that the OP's statement was truly correct that all that happened was a boost increase---- I may not have shared this -

BUT, how many times have you seen the OP's start out on one line of thinking only to have their eyes opened by questions to consider other factors they thought didn't matter ?

I know a mag shaft and the clearances internally are tight and they matter--- I have spent a few afternoons at Cirellos shop ----

As for how things get bent on a race car --------------------

 

Mike , I can't claim to know how it was bent -- I just know what I stated--- it had a bent shaft--------

 

B9ES NGKs-New MSD wires and New Plugs

I have been running B9ES NGKs for several years now with a Roots Blower, a 14-71 Kobelco Superman making 42 to 44#s of boost in a Top Dragster and never any problems like this before. This is new car to me, a heavy 2300# Promod with a converter, and new fathead BAE 5 headed motor to me, and just plain trying to work the bugs out before Winter now. I have put 3 new sets of MSD wires on for each pass with a new coil wire and new plugs each time and still drop random cylinders, and usually just one dead cylinder (or no hotter than 300 degrees at the end of the run), but sometimes 2 cylinders and they are good at the launch and then loose spark when leaving the line at 49#s of boost up to 55#s during the run. I have not ohmed the plugs or wires, just put new in for each run. I am completely rewiring the car now too. THANKS to all for helping and giving me more ideas. I will report anything I find and it may help some on here too. Like, Mike says the spark is following the path of least resistance and I do not know why, unless, maybe my boost is higher than I think and will recheck it also and close the sparkplug gap some more too! The large MSD cap has shown arcing on the outside and the white insulator on the plug sides shows up to 3 black carbon arcs down the plug sides-THANKS! Jim

 

You guys seeing random misfires with the larger gaps?

 

How about trying a different mag ????????????????????????? You have changed everything else from what is posted so far --

 

Could it be that a grease/oil film is getting on to the spark plug porcelain. This would give a electrical path to get to ground. Maybe the mechanics fingers are to oily when handling the plugs?

 

New Mag and clean spark plugs

I will try a new mag and make sure the plugs are very clean the next run. It looks like we are rained out at Montgomery Motorsports Park, AL. this weekend for the Southern Outlaw Tour too! It has been rained out most of the Summer now-THANKS! Jim
PS-Thanks to all for the advice and help!