Join Date: Dec 2000
Location: Monroe, WA, USA
you might also want to try a adjustable vacuum pot, like crane make's. ping is cause by how much and when the advance comes in.
a part throtle ping is normaly a vacuum advance issue.
IMHO you need between 10* and 15* of vacuum advance. it should start around 5 to 10 in. of vacum and be all in by around 15 in.
i also recomend if you do not run a EGR or other smog stuff to use manifold vacuum.
vacuum advance is what i call a idle timing aid, and a cruse efency aid. ported vacuum is not there till around 30MPH or higher and it is never a full vacuum source. a cruse at say 60 MPH your motor is makeing around 20in of vacuum, but ported only give's you around 8 or 10 in. of vacuum. that is why a vacuum advance pot for a EGR motor is all in by 8in. of vacuum. not as good thing in a performacne motor.
set your mechanical to come in by around 3000 RPM and be in the area of 20* to 25* of advance. set base timing at around 10* to 15* BTDC your traget is around 32* to 38* totale timing at 3000RPM with out vacuum advance conected. you will get anthor 10* to 15* with the vacuum advacne conected at idle and cruse, useing manifold vacuum. for a target totale of 42* to 53* with vacuum advance conected.
manifold vacuum also help's you keep your throtel plate's in what i call the "sweet spot", so you do not have too much transfer port showing and get an off idle stumble or a too rich idle mix. hope this help's ya out.
[This message has been edited by ilbl8 (edited 04-04-2001).]