The Ford Barn

Greg Jones · 03-05-2017, 08:39 PM

Well this is a new condition for me. My engine is running a tad rougher than I like, so was shorting out each spark plug as part of my check out. Cylinders 2, 3. and 4 were shorted out against the cylinder head and showed a healthy, snappy blue spark. Cylinder #1 showed a somewhat wimpy (and apparently intermittent) much weaker spark. So I thought, must be a defective distributor body and switched with another. Same results. Switched with another, with same results. The distributor is a rebuilt from Berts about 5,000 miles ago but kept oiled. Using standard points set to .018" on a Snyders 6:1 head using 3X Champions with gap set at 0.030". Using the Stipe machined distributor cam, lubed lightly. I also tried two other plugs (one new 3X and one used, same weak spark). The issue seems to be the distributor, however, not the plug itself.

Then I thought maybe plug is not properly grounding. There was some paint on the cylinder head so cleaned it off. Seemed to improve a tad but still not the same strong spark when I short out the plug as cylinders 2, 3, and 4. About the only thing I can think that would cause this is if indeed the bushings were worn such that when the distributor shaft comes around to cylinder #1 the point gap closes up (or I suppose it could expand too, if worn, widening the gap). Checking the bushings for wear, I am not visually seeing any but of course maybe a couple thou wear is hard to discern. Anyway, anybody run into this sort of thing, i.e., one plug receiving a wimpy spark when all the others were good and strong?

03-05-2017, 08:39 PM	#1
Greg Jones Senior Member Join Date: Jul 2010 Location: Aiken, South Carolina Posts: 697	Weak Spark on No 1 Plug Well this is a new condition for me. My engine is running a tad rougher than I like, so was shorting out each spark plug as part of my check out. Cylinders 2, 3. and 4 were shorted out against the cylinder head and showed a healthy, snappy blue spark. Cylinder #1 showed a somewhat wimpy (and apparently intermittent) much weaker spark. So I thought, must be a defective distributor body and switched with another. Same results. Switched with another, with same results. The distributor is a rebuilt from Berts about 5,000 miles ago but kept oiled. Using standard points set to .018" on a Snyders 6:1 head using 3X Champions with gap set at 0.030". Using the Stipe machined distributor cam, lubed lightly. I also tried two other plugs (one new 3X and one used, same weak spark). The issue seems to be the distributor, however, not the plug itself. Then I thought maybe plug is not properly grounding. There was some paint on the cylinder head so cleaned it off. Seemed to improve a tad but still not the same strong spark when I short out the plug as cylinders 2, 3, and 4. About the only thing I can think that would cause this is if indeed the bushings were worn such that when the distributor shaft comes around to cylinder #1 the point gap closes up (or I suppose it could expand too, if worn, widening the gap). Checking the bushings for wear, I am not visually seeing any but of course maybe a couple thou wear is hard to discern. Anyway, anybody run into this sort of thing, i.e., one plug receiving a wimpy spark when all the others were good and strong?