Re: #3 Exhaust Port Tube

Posted by Ross On 2011/9/25 19:29:39

I am a little confused. On an original 53 manifold the heat riser for the choke is cast on the surface of the exhaust manifold, rearward of the carb and is covered with a flat plate retained by two screws. In prior years the heat riser was a 5/16 tube that passes clean through the manifold on a diagonal by the #3 exhaust port. The tube is warmed by exhaust gas but is not open to it. A 1/4" tube is inserted in the top of the diagonal tube and runs up to the carb.

I have not yet seen one of those breached in 20 years of servicing Packards, but anything is possible. Put your hand near it while running and you will know the tale.

Valves that won't run quietly even when set properly usually have loose valve guides.