[Spridgets] pinking problem

[David Lieb]

Marc,
Manifold vacuum SHOULD be correct on a 1973, IF Jeff rebuilt it for that. 
The issue is that the vacuum source must match the vacuum diaphragm.

The vacuum gauge readings you are currently seeing could be cause by your 
having the timing off. Put the distributor back to the settings Jeff gave 
you and check the vacuum gauge at idle again. There are plenty of websites 
out there that can help you interpret the readings. Once the needle has 
settled back down, hook the blessed vacuum advance back up and drive it. 
Vacuum advance is there to enhance efficiency in part-throttle situations. 
It is quite unlikely that it is causing a real pinking situation.

There are two different kinds of pinking; both involve the fuel charge being 
ignited too soon, but one is caused by ignition timing while the other is 
caused by something in the combustion chamber being so hot that the 
compressing air/fuel mixture is igniting itself or else so much compression 
that it ignites itself like a diesel engine. Your description does not sound 
like pinking in its usual forms. Could you be running too lean? What do your 
plugs look like? For best results, run it for a distance on that flat road 
at 40 so you can hear it, then turn off the engine and coast to the side of 
the road and check the plugs. You might also want to do a compression check 
both dry and wet and let us know what it is doing. It is also a worthwhile 
exercise to find TDC on the #1 cylinder and verify that the timing marks are 
correct.
David Lieb
1972 1960 1974 1973