That would most likely be a slightly lean condition in that cylinder. Intake manifolds seldom have good fuel distribution. What intake & is it a Holley or Carter? It is possible you could stager net the carb so it feeds that cylinders runner a hair richer to solve the popping issue.
I'm running an Edelbrock TM7 intake and FITech fuel injection. That should be fairly easy to investigate. I can check/adjust the afr at cruise. Thanks for the input.
