Rick Mize Posted July 19, 2022 Share Posted July 19, 2022 I have a 1942 Mercury Eight with a 239 flathead. My carburetor has a copper vacuum line going down to a port just behind the distributor. I have been told this is rare on the flathead. I have owned the car since last year and it was running good but had a hesitation when I accelerated so I ordered a kit from Dennis Carpenter and rebuilt the carb. It's been a down hill battle ever since. The car ran terrible when I put back on the engine. I sent it to two different carb guys in Florida and it has come back from both with the same problem, can't get the idle right and no air adjustment to be had. It accelerates pretty good just flucuates when it idles. I need help! Link to comment Share on other sites More sharing options...
DFeeney Posted July 19, 2022 Share Posted July 19, 2022 I am surprised you have not measured your vacuum with the engine running. This is a simple check and will point you in the right direction with your trouble shooting. You will need a vacuum gauge with hose and a fitting to tap into the intake manifold below the throttle plate. Link to comment Share on other sites More sharing options...
Larry Schramm Posted July 19, 2022 Share Posted July 19, 2022 Here is a chart that should help you in your diagnosis. 2 Link to comment Share on other sites More sharing options...
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