[Rattlenshake]

It's pretty moderate - cammed for mid range torque vs. top end, so not much overlap which is what kills HC emissions. Holley 1850 on Wieland dual plane. Basic Ford HEI. I kitted the carb to make sure it was tight, retarded the timing by simply disconnecting the vacuum advance, raised the idle to around 1000 and carefully set the mixture to be right where when turning in the idle starts to lower. Can't go too lean or CO is too high. Engine was also plenty hot. Got a buddy that worked in a carb shop back in the day. He helped me through this. Then he tells me about the REAL 427 car that came into his shop to tune around 1972. Imagine that! Cats on your GT40? It might depend on the cam. It's crazy to have to go to that length for a specialty car. Tim Eyman where are you?