Posted by Matt Wilson [172.69.70.230] on Friday, February 21, 2020 at 09:49:35 :
In Reply to: Re: Probably answering my own question but... posted by Milo in Pa [173.245.54.80] on Friday, February 21, 2020 at 08:12:55 :
A few years ago, I spoke to a guy whose family was involved in the production of the Dodge/Chrysler/Pymouth/DeSoto flathead engines through their entire production run. He said that over the decades of production, there were some 80 or so different cam designs for the flatheads. I believe this was across all engine sizes - 201, 218 (both short and long block), 228, 230, 236, 241, 251 and 265 cubic inches - and across all applications, including a variety of cars, trucks ranging from 1/2-ton to more than 1-ton, airport tugs, farm equipment (such as combines), stationery equipment (such as generators, welders, compressors, pumps, etc), and who knows what else. The cam designs could have been changing during tue timeframe you mention. Also, distributor advance curves may have changed through those years.
Honestly, I almost have to think that it was more than just compression increases that brought about the power increases you mention. It's hard for me to imagine a 25% or so increase coming from just a compression ratio increase, but I'm not performance guru, so I could be wrong. Keep in mind that there were some years in the late 50s when a 2-barrel carb was offered by the factory. This can make a huge difference in power, and maybe the numbers you're reading came from engines with the 2-barrel setup. I once milled the head on my Power Wagon 230 engine to raise the compression ratio from around 7:1 to about 8:1, and I honestly didn't notice much, if any, power increase, going by my seat-of-the-pants feel. Of course, I probably reduced the airflow around the valves by doing so, and that may have negated a lot of the benefit of the compression increase.
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