[Healeys] Cam Timing

[David Masucci]

6 or 7 years back I did an amateur rebuild of my BJ8 engine. As of today the
compression differential from cylinder to cylinder is under 5 %. It sounds
mechanically tight and I think it is.

I've never been fully convinced that I have it running as well as I think it
should run. It runs good and pulls as I'd expect up to about 3000 RPM or so.
After that power seems to fall off.

I have myself convinced that I  understand and have correctly adjusted the
ignition timing, ignition advance, mixture, valve clearance, etc. After advice
from many people I finally decided to take the time to do something that I
should have done when I rebuilt the motor in the first place...I learned how
to degree the cam, and today I have taken very careful measurements of mine.

Using a piston stop I found exact TDC and set my degree wheel to zero. I have
the rocker out of the way on the number 1 intake and have my dial indicator
mounted above the pushrod. Always taking measurements after stopping rotation
in the proper direction, I found the point of maximum lift of the intake lobe
using 0.050" measurements from base circle AND I also did the same measurement
using 0.050" readings from the peak. In one measurement I got a point of
maximum lift as 1060 while in the second measurement I got a value of 105.50.
So I'm pretty confident that my number one intake hits maximum lift at around
1060 ATDC.

I understand that the spec for the BJ8 is 1100 ATDC for this parameter. It
appears that my stock BJ8 cam is about 4 degrees advanced from where it should
be. What can I expect from this error? Could 40 be enough to produce a fall
off of higher RPM power? I thought advancing the cam timing would give the
opposite effect? Any thoughts?? Does this make sense?

Dave
BJ8