Hey everyone.......i have been building merc 260 center horns many years....have a stuska test cell dyno that all of them run on for my customers and all has been well.....i am on the west coast and don't see hardly any 280's as a rule. I have one on the dyno now for 3 weeks and this thing just won't make power. Has compression, spark, fuel pressure......will wind up to 7700 and only make 100 hp.....have checked dyno multiple times and run other engines in between.....the dyno hp and torque cross at 5250.....checked the brake calibration.....MY son call this engine the unicorn.....it really exist but won't make power......i hook it up to DDT and richen it up.... only thing i cant see is the advance on the dyno at cranking with timing light ,while throttle being advanced..,WTF

Driving me nuts