Don65Stang
Well-known member
After putting in new plugs & wires I thought I would play with the timing a little via the vac gauge method instead of using the timing light. My initial timing produced 15 in Hg. I advanced the distributor between 1/2 to 1 inch and the vac went up to 20 in Hg and it was purring really nice. Had to lower the idle screw some even. I plugged in the manifold vac to the vac advance and started backing out the driveway. Pinging all over the place so I retarded it some and tried another drive. It did better but mid range pinging under acceleration.
Btw, it is a '73 CJ which, of course, has open heads.
For this method I'm after the highest initial timing that gives the most vacuum. I then have to check total timing (mech and initial) and not be more than 36 BTDC. If more than 36 adjust the mechanical to get to 36 (more on that in a later post). Then if midrange pinging still occurs...go with a stiffer light weight spring on the mech advance so the mech advance comes in a little later.
I kept retarding the distributor until the pinging stops like it was before I messed with it. I need to determine optimal engine RPM I want for when the timing is all in. More to come later.
Btw, it is a '73 CJ which, of course, has open heads.
For this method I'm after the highest initial timing that gives the most vacuum. I then have to check total timing (mech and initial) and not be more than 36 BTDC. If more than 36 adjust the mechanical to get to 36 (more on that in a later post). Then if midrange pinging still occurs...go with a stiffer light weight spring on the mech advance so the mech advance comes in a little later.
I kept retarding the distributor until the pinging stops like it was before I messed with it. I need to determine optimal engine RPM I want for when the timing is all in. More to come later.
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