Doing the 500 hour on a slick 4347 mag, installed both sets of points and the primary timed fine, but the secondary points just would not open. These are the m3637 ones and so I moved them back and forth and when I torqued them down, the cam would not even touch them to get them open. So I got another set and those timed perfectly for the 25 degree lag. This is just a reminder that new parts are not always good parts! Tim