"Why anyone would stop up a cap is a mystery to me because that is the only place back pressure can escape on an A engine."
Why? Because this advice was printed many times in the "Restorer" over the years, as I mentioned in my previous post. Tens of thousands of eyes read this advice and many followed it - BECAUSE it had appeared in that magazine. So it must be true, right? I learned a long time ago to take a grain of salt with any suggestions for improving the Model A that appeared in the national magazines, unless they came from a source I knew to be knowledgeable, not someone who drove his Model A to the ice cream store and back once and was now an expert.
Marshall