Quote:
Originally Posted by torqjunki
Thanks!! I like it. I don’t see LSA
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It's there on the cam card, you just have to do some math to see it. (109+119)/2 = 114.
What I like about this cam is how well the engine likes to rev. 4" stroke (434 cu in.). Enough torque to get wheelspin (with 255-section tires) by hitting the gas at 55 mph in 2nd gear (which is pretty ridiculous on the street!). So it makes good torque plus has that nice, high-RPM lunge (shift at 6500).
And even though these 72cc heads have the old combustion chamber, max power happens at 31 deg total timing. With the old 87cc heads, I needed 37 deg. So good quench combined with high compression seems to work here. (11.4:1 on the 72cc and 9.7:1 on the 87cc)
Note that I did not just swap heads when going from 87 to 72. I also decked the block to make it parallel to the crank but also got the pistons slightly above the deck (forgot exactly how much). So I increased compression plus quench at the same time.