[Sboxin]

Its time to refresh our 3.8L 964 race engine. Here are a few photos of valves, spark plugs and heads. We have about 70 hours of run time but some are warmup time - the rest are race time 5000 to 6500rpm and a bit to 7200rpm

Do the plugs and valves look like a lean running condition - we are using a SW dyno tuned Motronic chip/ECU at a level 13 AFR - stock intake and custom exhaust headers ?

We seem to have a head lifting condition showing exhaust head leakage - what do you think. Some think this is from an overheated combustion chamber caused by a lean fuel condition - What do you think? We are using Supertec head studs and none were loose. We have sent the stock 964 fuel injectors out to be tested and cleaned thinking this may cause a lean condition - and will add an O2 sensor/gauge data logging system when putting the engine back into the car. Some racers have upgraded the injectors to a Lucas 24# that may run a bit rich at high RPM - what do you think ??

Also, the engine has JE 12.5CR pistons and Webcams 20/21 cams running on 100octane unleaded race fuel (to try and cool the combustion chamber/heads)

The crank, rods, heads and pistons are at Ollies with flywheel for testing, cleaning and balancing and new exhaust valves.

The rod bearings need to be replaced because of minor damage - the crank bearings are fine but will be replaced anyhow. We will also replace the piston rings.

Our engine builder is Don Jackson Enterprise here in Phoenix - they built this engine in 2012 and refreshed in 2016. My son drives about 6 races a year now that he has young children :-)) He plans to drive at NASA Nationals at Laguna this September.

Thank you for input to my questions.

Regards,
Roy T