I am having plenty of strife with the timing on the old girl. at idle i can get it timed perfectly, running better than when i started but it keeps advancing itself under any load. i have checked that the harmonic balancer hasn't spun and its all fine. i was thinking bout throwing in a dizzie off something like a blue/black 308 to do away with points etc. what else is needed for me to do so ? or whats the best option ?

G-day MarkS
There are a few ways your timing can drastically change . Either the roll pin retaining the dissy drive gear has sheared and the gear has seized in a different position or the dissy clamp is not holding the dissy tight enough
if you can get the timing back to normal by adjusting the distributor then obviously the proiblem remains with the dissy and not the timing chain/gears. How far does it advance and does it advance to far if you increase the revs slowly and have you checked the vacum Regards Graham

hey graham,
i have checked the vacuum and it seemed ok although the diaphram did seem to return slowly. when i increase the revs it advanced up to around 12 degrees too far. if i put a different dizzie on it off a later model v8, where the coil is incorporated on the dizzie, do i have to change anything else ? i have an A cell coil on there at the moment.

MarkS
You're talking about a GM HEI distributor and , no you don't have to change anything else.
The connections on the side are for power,earth & tacho.
The other thing that can go wrong if it's only advancing 12 degrees is the centrifugal advance springs. if they are broken or have come off . the advance weights can open up very easily.
Are you able to check Total advance
Graham

hey graham, thanks for your input,appreciate your help. im not a mechanic mate so your gonna have to tell me how to do that.

MarkS
It depends on the type of timing light you have. A digital one with manual advance is the best
but you should get total advance at around 3000 rpm
Just increase your rpm and see what your timing light says
Total advance is the combination of both vacum advance and centrifugal advance.
Graham

hey graham,
Thanks for all the advice you have given. she's purring better than ever now. Appreciate all the help mate. Hope to meet you at a club day or something soon.
MarkS