Home › Forum › Ask A Member › 1966 18 hp fastwin › Reply To: 1966 18 hp fastwin
Why don’t you post a picture of exactly what you filed…. From what you have written, it would seem like you ground the brass notched cam that hits the vertical shift interlock rod…. But, I’m guessing you ground something else that actually allows a little more spark advance and opening the butterfly a bit more. Sounds like you ground “just a little bit”, but that could be enough to cause detonation/preignition….
Did you notice any change in WOT performance. In actuality, you did make an attempt to address a bit of an engineering flaw. Altering cam pick up adjustments can also affect WOT butterfly positioning, which there is no way to adjust…. Perhaps your throttle cam pick up is not set correctly, or the rubber cam follower roller is worn/grooved keeping the butterfly from opening fully….