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Old 04-03-2023, 10:16 AM   #13
blucar
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Location: Ventura, CA
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Default Re: 239 flathead, block the heat riser passage, or no?

Quote:
Originally Posted by Pete View Post
One of the percieved benefits of blocked heat risers was noisier pipes if you had Smittys. More noise equates to more hp. Many bench races were won for the measly cost of 2 pennies

Back in the early '50's when I was a teenager working on improving the performance of engines it was very common to block the heat risers of flathead engines and eliminate them from inline engine manifolds.
The purpose was to increase the noise, especially 'rap' on twice pipes. The down side was that the engine ran rich and cold.
Of course as 'pete' said, the myth that noise means more horse power, is just that, a myth.
Of course when I got older and smarter, got tired of having the cops on my tail for excessive noise, quite stealth became my motto.
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