well my sanfu the vacuam advance line to the carb if you suck on that and put a clamp on it runs but if you dont it wont run and it back fire with it and without and and after a while of runnning it and you shut it off it wont start.and move the timing belt one tooth each way and stuff. what do you think it is?
if you suck on the line to the distributor you can hear the vacuum advance working??...if it is working and then you attach the vacuum line it dies ..then you have a timing problem....you may have to pull the distributor and check the advance unit,and pickups under the rotor
the line goes from the carb/intake to the vacuum thing that moves the points it doesnt have a distriutor.
vacuum leaks are 85% of carb and idling problems, use a vacuum gauge or carb cleaner, carb cleaner will send the engine to high idle if you have a vacuum leak, make sure the vacuum port in the air cleaner canister is working properly, also check that your vacuum advance hose isn’t cracked coming off the distributor to the vacuum manifold tree. The vacuum manifold tree is brass on the bottom to go in to the block and plastic on top. Plastic wears out with time and will break or leak, which causes a vacuum leak. Some manifold vacuum trees are 3 or 4 port, make sure to replace it with a new one. When I buy parts I buy 3 at a time that way I have them on hand or in case they can’t get them any more. The vacuum manifold tree is located behind the carb. If you looking at the carb from the right side of the bed, it will be to your 1 O’clock tucked down inside. Remember to use a marker or different colored tape to mark the vacuum lines so you know where everything goes back too! Good luck!’
