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Posted by Chris Case on Monday, June 09, 2008 at 12:50:58 :
In Reply to: My oil bath was rotted out from condensation? rain? posted by chris case on Monday, June 09, 2008 at 12:11:28 :
This may complicate things a bit:
Changing air flow restriction may change jetting in a counter-intuitive direction.
The carburetor inlet bowl vent has three purposes.
One is to vent the fuel bowl.
Another is to act as an air scoop such that incoming air flows into the bowl, and causes positive pressure. The pressure pushes more fuel through the jet, adding additional fuel to the additional air that is flowing in.
Plus, this last operation acts to prevent a restrictive filter from acting as a choke- the more restriction, less air flow, means less bowl pressure, so less fuel also. This way, a clogged filer not only cuts down on air, it cuts down on fuel too. Causing low power, rather than acting as a choke.
This all has to work in balance. The way to adjust the balance is to re-jet. Rochester Quadra-jets work if you sand/file off the end, otherwise they hit a plug in the fuel passage.
I always planned to re-jet, my carb being a mongrel. I did the seat-of-the-pants power-jet. It had a lean surge, so I up up jetted about .010". Ran good, next jet I tried was between the two. Still ran good. Next jet was between the two lean ones, back to surging. So back to the mid jet, good to go.
I'll get the truck out to may buddy Mark at the Dyno shop in Santee for an 'after' test soon. I also installed a Mopar electronic dist that Mark had curved. So it ought to show good improvement.