1969 Daily Driver
Ok Cam talk time. So as we know I am new to these leaning towers of ok power. I have always wondered why the stock valve setting are what they are 0.010"/0.020" and now I have my answer and a very good reason why you NEVER pick a cam based on advertised duration. So I pulled out a a few 100% stock cams 1968 and 2 1969 cams and they have the exact same specs so we are good on that. Duration at 0.050" 175/184 on a 110 lsa with a lobe lift of 0.217"/0.231" but here is where the funny business comes in. The ramp rates now let look at the intake first, duration at 0.005" 229, 0.010" 217, 0.020" 201, 0.050" 175, 0.100" 141, and 0.200"72. I design cam profiles for a living and these are more in line with modern Hydraulic flat tappet profiles hence the reason for the 0.010" lash. Now the exhaust is 100% like a solid flat tappet should be for that time. Duration 0.005" 326, 0.010" 271, 0.020" 223, 0.050" 184, 0.100" 148, and 0.200" 71. Now this is why the the lash on the exhaust is set at 0.020" because that is when the ramp rate really starts to move fast. The cam that I am doing for my new slant six is going to be a duration at 0.050" 204/208 on a 110lsa with a 0.299" lobe lift. These masters are true solid profiles so the lash will be 0.020" intake and 0.022" exhaust when done. So for me the age old mystery of this lash has been solved.