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Old 02-22-2011, 12:49 PM   #7
Ron in Quincy
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Join Date: May 2010
Location: Quincy, CA.
Posts: 1,708
Default Re: Backfiring Model A

One of our club members called me yesterday and said the carburetor I rebuilt for him was acting up; did not want to idle smooth, backfired when trying to excellerate.

The first thing I suspected was lean mixture, possible float setting too low, or blocked fuel flow. When I checked the carburetor the bowl was full to correct level, no shortage of fuel and good flow. I removed the carb, the bowl was clean, no blocked passage ways. Rienstalled the carb, turned on the gas and filled up the carb; no leaks. He started the engine and it ran poorly, backfired when trying to excellerate.

I asked what else he had done and he said, checked timing, installed new distributor with V8 points, set the new points.

As I couldn't find a problem with the carb, I opened up the distributor I found the point rubbing block was setting between lobes on the cam but the points were open; when setting on the lobe he had over .045 clearance on the points; readjusted the points to .020 and the engine started, excellerated good.

As usual, 95 percent of problems are electrical, but the rebuilt carb, in the mind of A'er, is always the problem !!!!

Ron
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