I have suspected that my cam timing might be off by a notch, so i have played
around a bit with advancing or retarding it. I have a variable +/- 6 degree
sproket that I experimented with. Retarding seem to instantly worsen
performance (lower compression) . From what i belived was correct cam timing,
as I advance the timing up to 6 degress, my previously lower compression
readings of 160 psi rose uniformly. At +6 dgress, the compression had risen to
180. I got brave and replaced the adjustable sprocket with my orignal
sprocket advanced 1 full tooth (15 degrees i believe with 1 tooth on 24 tooth
sprocket). I confirmed that ther was no valve contact and tested the
compression again. To my pleasant surprise, the compresson came all the way up
to 195 (again unform). Looking at the cam with #1 on TDC, the cam now appears
oriented on #1 more like 11/3 instead of 10/2.
I am assuming that the higher compression means that the cam timing is now
more correct. The engine seems to have more power as it should. I am just a
bit spooked by the cam position and I dont want to damage the engine
otherwise. Can anyone tell me if it is possible that the compression can be
significantly higher if the cam is incorrectly advaned? I have not been able
to find specified normal compression readings for a U20, but I know that a
strong engine is typically around 200.
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