Check around your cam tower. Is it leaking oil? If it is leaking back by number 4 you would have oil drip on you hot #4 exhaust runner which would create the poof of smoke and it may be running down the front side the cam tower where it is collecting in your spark plug hole.
It may be your cam tower gasket.
Speedy
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1983 944 guards red with 16" Fuchs, Host of Wisconsin area timing/ balance shaft belt tensioning party
1987 944S Purchased from Legion. Corvette LT-1 V-8 conversion with Mega Squirt II
Check on progress --->
www.porschehybrids.com/gallery/speedracing944
Favorite Road =
www.tailofthedragon.com 318 turns in 11 miles (11 min 20 sec best run)