for the aths southbend trip, which was a good full power round trip run of 1300 miles in my 40. a fresh rebuilt 270, rebuilt zenith carb and 4.56 rear gear i averaged 13.5 mph. with a road speed of 50 and a rpm of 2400.

what do your plugs look like?

40 GMC 250 STAKE/FLAT BED
1951 Chevy 6100 Dump
51 GMC 350 ENGINE 500/500
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