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Hi,

After now having put 700 miles on the rebuilt engine, I have been wondering why I never ping on regular gas, and why my mileage is so awful. This morning I popped the hood and after letting it war up, I pulled the vacuum line off the dist and found out that I am not getting any ported vacuum even with the throttle opened half way up. Normally you can feel something on that line with your finger, but this seems to have no vacuum. The metal line from the carb port is new, and not bent or broken. What's the most common cause of getting no vacuum off the port, a wrong gasket?

1962 Autolite 4100 1:12 throat, rebuilt, car set at 10* btdc. Other than this, it runs fine.
 

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Most likely junk in the vac passages. I would disconnect the hose from the distributor, hold the end with a rag, and stick the tube of a can of spray carb cleaner in it to back-flush. Try to pinch the hose to seal around the carb cleaner spray tube, but wear eye protection just in-case. Hold the throttle wide open (wire it open temporarily) and you should see carb cleaner squirting out the transfer holes near the bottom of the bores. If not, and a bit more squirting doesn't help, it's time to pull it for a clean-out.

David
 

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BTW - make sure you're using the correct port for the vacuum. It's the one on the right (passenger side), just behind the forward mounting ear. See pic.

David

 

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Did you pull the hose off and check it at the port? A cracked vacuum hose or loosely fitting hose on the port will lose your vacuum.
 
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