So I've been following this tutorial: http://slantsix.org/forum/viewtopic.php ... ht=#322691 while attempting to degree my Comp 252s. I think I have everything figured out, except that I am 16deg. off between the two ways of measuring.

Straight up, them cam was at 111.5 centerline... So I advanced it 4deg at the crank (JP Performance double roller timing set), and am now at 108deg centerline (cam card specs 106). That part I can figure out.

When I move on to the "open/Close Method" is where things go awry. I'm coming up with 16deg more of advance than with the "Centerline Method." This # difference was the same before I advanced the cam, as well as after.

I'm lost.

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If the lobe is assymetrical (the front ramp is steep and the back of the lobe is longer and a little lazy maybe) or ground short, the .050 opening and closing events could be different than the lobe centerline method. I had that problem when checking another comp cam-256Xtreme and the Erson 280/270, the lobe was a little off at the .050 from base method.

Set the cam using the centerline method and call it good.

One thing to note on the tutorial, my performance machinist and engine builder buddies do not rock the cam back to .050... if you have to roll it back, roll it back to at least .125 before, then slowly work up to .050, this allows time for the timing chain to take up the slack and make sure your numbers are correct during the normal movement of the timing chain (most double rollers are fairly tight and may not matter...if using a standard silent chain you might have a little slack-either way it just takes a little bump and something can be a little off).

-D.Idiot

Rob, thanks for the reply, and for walking me through this on the phone (sure would be nice to have internet at the shop...). I got it dialed in at 106.5 and called it good. Head and valve-train were on before I called it a night. I need to set the valve lash, measure and set my cam button, and then finish putting on the peripherals tomorrow.

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