I measured my Mod Nova 28 on the metric engine programme ,and got 185exh Rotor opens 219 ATDC and Rotor closes at 65 with a totel open duration of 206. The blowdown is 31.7 as expected because this engine was modded to rev. What surprised me though was the button CC volume of 0.37cc !! with the plug in,,which will end up with a trapped CR of 7.6 that's without a any shims and .0.16" clearance ,I not sure why the button was enlarged so much,,although this is a converted car engine to run low 25% nitro . I am thinking a new button made to 0.26cc for high nitro and set clearance to 0.008" for a trapped CR of 10.5 .which will give the engine more torque to pull the prop better.