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Hi,

Its been a while, more a tribute to my trusty steed than anything else!

But obviously, I am now here and in need your esteemed help.

All of a sudden the motor has developed a problem which has me preplexed, it starts ok but won't fire on all cylinders for some time until it gets warm, it's blowing out some black smoke during this 'mis-fireing' also. When it gets hot it runs fine. Plugs are getting sooty, not oily, changed coil, leads, plugs and adjusted mixture to lean it. Carb cleaned, everything looks fine.

Valves were recently adjusted, maybe some issue there?


Any ideas guys?

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Dear IrishPackard:

Let's see:

Overchoked - Miss disappears when warm

Underchoked - miss disappears when warm

Sticky valves - miss disappears when warm

Stuck open heat riser - miss disappears when warm

Faulty breaker plate/bad distributor ground/faulty breaker gap - should miss during uphill acceleration

To test igniton get a calibrated spark tester from an auto store. Your car should produce a minimum of 20 Kilovolts with 25Kv optimal.

Next hook up a vacuum gauge. If the needle is fairly steady and 17inhg or higher you have a system problem not a mechanical problem.

Some carburetors will be overly rich when cold because they are worn out and the choke pull off doesn't work anymore, but low motor vacuum can also cause this problem. Thus, do a compression test. Choke pull offs need at least 90psi of compression to work.

Good luck with your car.