924RACR
Joined: 29 Jul 2001 Posts: 8815 Location: Royal Oak, MI, USA
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Posted: Fri Jul 20, 2018 9:50 pm Post subject: Hot running misfire |
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Just a quick note to say that, after driving the ('82) Turbo all week in some rather hot weather (up to 90F, including stop-n-go) I can confidently say my heat-related misfire is gone.
The heat sink on the ignition unit was key, along with finding a good/reliable ignition unit, but more than anything else re-attaching the ignition unit to the heat sink with electronics heat sink attachment paste - heat conductive, like used when assembling a CPU to a motherboard.
Night and day difference.
I also, BTW, tried some spare ignition units with a smaller heat sink, a newer style, they're riveted with a hollow rivet to something that's little more than a solid brick of metal. They clearly don't have the capacity, from my results - they would also misfire when they got all hot.
Older ignition controller, with the big finned heat sink and proper heat-conductive paste, works like a champ.
Just wanted to throw it out there for anyone having such problems.
Next up, gotta try replacing my valve stem seals... despite rebuild, seem to have a failure there, perhaps one went in poorly... going through a spectacular amount of oil at the moment... _________________ Vaughan Scott
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'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype |
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