I recently finished putting my cpc 1300 motor together in my M7 141 chassis. I kept the M7 diamond drive and 10" secondary, but put in a higher gear ratio in (don't remember exactly what it is right now) thinking that with that motor and that short of a track, I'll have plenty of torque for the higher gears. Dale has clutching recommendations for the 1300, but of course in my situation there are so many differences his recommendations can't be very reliable, but I thought I would start close to his recommendations and go from there. I have a P85 conversion in for the primary, and have cutler's torsional conversion on the M7 secondary. I bought an orange secondary spring for the secondary (his recommendation to start at) and have a straight 44 helix. His helix recommendation is a 42/38, but I thought I'd just start with the straight 44 since I already had it and figured it would give me a starting point to go from just as good as the 42/38. Anyways, the orange spring is EXTREMELY stiff. It's stiffer than any other secondary spring I've ever used before. It took two people to put the clutch together and to put the belt on, there was NO way to simply force open the sheaves to fit the belt in without screwing in the belt deflection adjuster WAY in to open the sheaves. I haven't had a chance to run it yet, but it got me thinking that with that stiff of a spring I will have to run LOTS of weight to clamp the belt hard enough to force the secondary to upshift. In my mind I think that with that much weight clamping down on the belt, I probably won't get very much or any at all belt slippage at the primary. If there's little or no belt slippage at the primary, all of the power the motor is creating is getting transfered to the secondary. So when I hear about some people going to lighter weights and a steeper angle of helix, is that not as efficient as the other way around? It makes sense in my head that if you minimize the slippage at the primary, all of the power is getting transfered to the secondary and that if you have a stiff enough spring in the secondary to reduce slippage there with the correct angle of helix to keep the rpm where it needs to be, that power will then be transfered to the track. Am I out in left field or does that even make sense what I'm thinking? Another way of saying what I'm saying is that clutch tuning should be doing what you need to, to eliminate belt slippage as much as possible in both the primary and secondary so that all of the power created by the motor is transfered to the track. Does that make sense?