Vacuum leaks (manifold to head, carb to manifold) or incorrect carb
jetting ( the same carb may fit different engines and use different
jets. If bought as a rebuilt carb, it might not be jetted right).
If those are ok, then double check the timing. Sorry, but your mechnaic
is a human and can make musteaks . . .messtake....errors.
Look under the hood for a vacuum hose routing diagram. If it's gone,
you'll need to get a manual with one in it. Then just trace each line
down according to the diagram.
Of course, just looking around under the hood may locate a leak or two
from old lines that have gone bad or simply fallen off. A stuck EGR can
cause ping also.
The vacuum advance only works when under part-throttle and cruise
conditions. It can be tested in the drive way with timing light by
pulling the distributor vacuum line off at 1/3 throttle, ( about 1800
RPM, if you have a tach), plugging it with a finger and seeing if the
timing setting returns to about 10 degrees BTDC.
Well, the hard part would be to try and find the right jets since the
carb is pretty old now, the easy way would be to find a carb on a
junkyard engine and rebuild it yourself.
Happy New Year!
Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here.
All logos and trade names are the property of their respective owners.