Has anybody seen this or am I getting too persnickity?
73 750.
Timing mark on flywheel jumps around at relatively high RPM... say 5000+. Partialy retard, partially advance. Looks like 5 degrees each way. 10 degree swing! Starts out dead calm then at the higher RPM the mark jumps around.
Reground B10 cam. I seem to recall this on the stock cam as well (too much happening to chase it down at that time).
With Dyna III module, distributor pick ups & dual plug coils, I think the right cyl jumps more than the left.
In a seperate stock distributor, with stock dual points and stock Guzzi coils (Packard wire and NGK plug caps) both cylinders dance around beginning at about the same 5000+ RPM. Maybe right more than left... maybe left dances in a tighter RPM band.
Using a different disributor gives me similar symptoms. The distributor springs etc MAY be bad on both though.
I am not sold on the cam moving against the stop (under the cam gear) thus changing the relative position of the distributor drive against its gear. Could be though... maybe a thrust bearing might help ... or at least shim closer.
Could be my Sears Best timing light. I'll try a different one tomorrow. Maybe two timing lights simultainiously might shed more light on the problem (ugh). One on each plug lead? Two lights triggered on same plug wire? hmmmm
Whatcha think? I race this thing WOT and I'm certain that an inconsistant ignition timing is not the way to best HP.
Alex
73 750.
Timing mark on flywheel jumps around at relatively high RPM... say 5000+. Partialy retard, partially advance. Looks like 5 degrees each way. 10 degree swing! Starts out dead calm then at the higher RPM the mark jumps around.
Reground B10 cam. I seem to recall this on the stock cam as well (too much happening to chase it down at that time).
With Dyna III module, distributor pick ups & dual plug coils, I think the right cyl jumps more than the left.
In a seperate stock distributor, with stock dual points and stock Guzzi coils (Packard wire and NGK plug caps) both cylinders dance around beginning at about the same 5000+ RPM. Maybe right more than left... maybe left dances in a tighter RPM band.
Using a different disributor gives me similar symptoms. The distributor springs etc MAY be bad on both though.
I am not sold on the cam moving against the stop (under the cam gear) thus changing the relative position of the distributor drive against its gear. Could be though... maybe a thrust bearing might help ... or at least shim closer.
Could be my Sears Best timing light. I'll try a different one tomorrow. Maybe two timing lights simultainiously might shed more light on the problem (ugh). One on each plug lead? Two lights triggered on same plug wire? hmmmm
Whatcha think? I race this thing WOT and I'm certain that an inconsistant ignition timing is not the way to best HP.
Alex