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There is a pin that installs into the cam lobe. The fly weight pushes it out to provide a small amount of lift when starting. When the rpm comes up at start up the flyweight swings out letting the decompresiom pin to retract back into the cam lobe and no longer provide valve lift on compression. Sometimes the pin will break off and disable decompression. The pin and flyweight can also become worn decreasing lift. Even a few extra thousandths of valve clearance can affect its function.
 

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The pin has an E clip on it to retain it. I am not sure about the profile on the lobe but I am pretty sure that the spec for the exhaust lobe and intake lobe are the same measurment so if they measure the same I would say it is ok. I dont have the book in the house but if you need the spec to measure for wear let me know and I will dig it up. As for wear you may want to look at the lifter for wear also on the side with the flater lobe. I live in the Kenosha area about 30 miles south of Milwaukee. If you cant find a cam let me know I may have one with a good pin in it. I just had my dads engine apart this summer thinking that that pin broke again because it was starting hard and it turned out to be the CDI unit. It was fixed and it ran up around 14 hrs and then started to quit intermitently and then finaly quit running due to no spark. Had to install another CDI unit and now it is running again.
Roy 262 945 7693
 

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The longest pin I have measured was .960" long. It provided .042" of lift at the push rod and .032" lift at the valve with .010" valve lash. I believe that the .042" measurement would be the same amount of pin sticking out from the cam. I have another engine I measured .032" lift @ the push rod and .012" lift @ the valve ( did not measure the valve lash but it must be around .020") and it seems to function fine with only .012" decompression valve lift. The surface that holds the pin out does tend to wear and decrease pin length. I tried welding one up and ground it back smooth and I must have recontured it wrong as it had more pin sticking out but the valve spring pressure was unwinding the fly weight resulting in next to no decompresion valve lift. I took apart several cams and used the best parts to obtain the .032" and .042" lift mentioned above. I also did some compresion tests with valve lash set @ .010" and then opened it up till no decompression lift was present. If I remember correctly compresion went from around 80 psi to 120psi.
 
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