[Bugger i was too slow]
if you are checking the timing with the vaccum connected you will pulling in an extra 7 8 10 degrees via the vacuum as soon as the throttle plate passes the vaccum port. Not syaing you are but the symptoms you describe sounds like you are
plug it at the dizzy end of the pipe with a nice screw so it can't get in the way of measuring mechanical advance.
initial + mechanical + vaccum can result in 45+ degrees under ceratin circumstances (which is fine, those circumstances need that advance for emissions and ecconomy)
spin it to 3500 and set it to 34 BTDC
let it idle and measure what you got at idle
if its at 5 BTDC or something daft like that you need a recurve kit that takes out 8 or 10 degrees * from yoiur distributors mechanical advance so you can set it to 12-15 BTDC at idle and still not go over 34 at 3000 or so.
then connect up your vaccum advance and don't worry about what it is doing at the mo.
as long as you have it connected to a port that enters the carb just above the throttle plates you will be fine.
* speak to turnip. if you have a mopar dizzy he can provide an FBO recurve kit
springs
a limiting plate
set of instructions
plate sits on top of the advcance plate and limits how far the Tabs in the advance weights are allowed to move outwards therefore limiting mechanical advance in the dizzy. plates come with a number of holes labelled on the diagram so you can choose how much you want to take out
use springs to adjasut how fast the advance comes in
use instructions for a nice bit of bedtime reading before starting
(helps to avoid firing the circlip that holds on the armature into a hedge like i did)
Dave
