MSD6A dying in the heat

[c4racer2]

did a pretty good heat stress test on my car this weekend - about 2-3 hours of stop and go driving for a cruise event as part of a car show in Saratoga / San Jose CA. Some pretty cool cars showed up - this red Chevelle had a nasty sounding BBC and manual trans and 305's tucked under the back, and the C3 convertible was a L88 car!

In my 71 Camaro w/ 520hp 406 w/ T56. Ran great. Stayed cool water and oil temps 185/205. But at one point the car just cut off clean like a switch - no sputter - would not restart. Pushed to the side of the road and let cool for 10min and fired right up. Did it again 45min later after more driving in the 90's temps and same thing - started up fine after 5-10min cooldown period.
Ironically my buddy and I were talking about roadkill at a stop light when the car died which basically put us right into our own episode of roadkill. Massive irony. Also said something about the car running great with all the traffic during the cruise which I'm sure angered the car Gods - "hey not on my watch pal - boom - ignition dead, see how you like that"!

Could be a coil - running a HEI with unknown set-up. I am going to replace the cap and coil and rotor for good measure. But I suspect the 6A unit. It was super hot to the touch. I run a .045 plug gap btw. Voltage was good at the time - right at 14V, charging system working fine - pretty new 105A powermaster alternator.

So I may move this to the cabin - but I also may junk the 6A and get something more modern. I notice this Pertronix draws maybe 1/3 the amps of the MSD which means it has to run cooler. Anybody running one of these?

https://www.summitracing.com/parts/pnx-510/overview/

[TheJDMan]

Next time it dies you can quickly check the 6A by cranking the engine while having someone watch the LED on the box. If the box is working correctly the LED will blink as you crank the engine. I have my 6AL mounted in the exact location you have yours and have never had an issue. I have had a coil take a dump leaving me dead but it would not restart until I replaced the coil.

[AMSOILGUY]

I keep an extra 6AL box around so I can test and rule it out easily. I had problems like this before and it was fuel related. I had to redo the venting on my gas tank. GL

[AMSOILGUY]

Originally Posted by TheJDMan

Next time it dies you can quickly check the 6A by cranking the engine while having someone watch the LED on the box. If the box is working correctly the LED will blink as you crank the engine. I have my 6AL mounted in the exact location you have yours and have never had an issue. I have had a coil take a dump leaving me dead but it would not restart until I replaced the coil.

I didn't know you could test it that easy thanks.

[c4racer2]

Originally Posted by TheJDMan

Next time it dies you can quickly check the 6A by cranking the engine while having someone watch the LED on the box. If the box is working correctly the LED will blink as you crank the engine. I have my 6AL mounted in the exact location you have yours and have never had an issue. I have had a coil take a dump leaving me dead but it would not restart until I replaced the coil.

Good to know. I’ll try that if it happens again. Although not sure I will keep this on my car at this point.


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[c4racer2]

decided I will stick with MSD, but picked up the model they build for the NASCAR guys - 6ALN, which is still a fully analog box and built with better components. It's about $100 more than the 6AL digital box. Will run that with a Blaster 3 coil and a Billet magnetic pick-up distributor. That should be a pretty robust set-up. Also allows me to get a better ignition curve for my motor and run 20 initial instead of the 16 I can get today with the old HEI and still run 36 total. Yes I could re-curve it, but that is an old stock disty must be 20 years old at this point so at a minimum would need everything replaced if I were going to stick with that. Perfect time to make the switch to a magnetic pick-up. I've run that disty before - never had an issue with it. I think that trigger puts less stress on the 6A box too.

[Che70velle]

I fielded and drove a NASCAR late model in the early to mid 2000’s. I put thousands of laps in and I have to say that the number one most common issue we had to deal with was having enough extra MSD 6ALN boxes on the truck. Those things dropped like flies back then. We’d build our ignition setups with dual boxes on an A-B switch within easy reach when a box would fail. I bet I bought a dozen of them in 6 years. Probably more. It was a common running joke in the pits among all of the late model guys. Everyone of us, 25ish cars every week, had same issues. Electrical is my skill set, along with engines, as I own an electrical contracting company that pays my bills, so it’s not like I didn’t know how to wire my cars. Not trying to discourage anyone here, just sharing what we went through back then. We were mandated to run that box, per our rules, so we had no options. I never lost 2 in an event, but I lost 1 of them on many occasions. We mounted them up on legs so air could get under them. Pulled fresh air on from right side of car to blow across the ignition board, and rubber mounted it all. It got to where no one in our class would put the MSD sponsor stickers on our cars, that we were supposed to run as a track sponsor promotion package. Harsh environment for sure, and definately not a street environment for us, so hopefully these work well for you in a street car environment.

[IMPALAMAN1]

SBC, 6a box blaster coil billet distributor. Car ran at 185ish. Cruising along it would quit. Put new box in, new coil... nada... ended up being the 20$ magnetic pickup in the distributor. Part that sucked was yo had to pull the distributor, pull the gear and shaft to get to the 2 screws that held it in. Major headache but ran fin, no hiccups after.