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Old 09-12-2023, 12:48 PM   #2
JayJay
Senior Member
 
Join Date: Jan 2020
Location: SF Bay Area
Posts: 1,127
Default Re: maximum rpm, personal choice...

Quote:
Originally Posted by TomInCologne View Post
Hi guys and gals,


my personal and completely subjective maximum rpm that i drive my engine at is 2.300rpm. My engine has not been opened up during the last 92 1/2 years and i feel that's the maximum i want to run it at.


Speed at this rpm is 50mph. According to hearsay, the maximum speed for the Model A, without overdrive or similar, is 65mph. That gives us an engine speed of 3.000rpm.


Do you drive your stock engine, with babbitt, with an unbalanced crankshaft at that speed?



thanks for your thoughts and input...
Tom - I don't have a tach, but I drive my '31 comfortably at 50-55mph indicated (actual may be a couple lower) on a smooth freeway. On downhills I've seen it creep up to 60+ indicated until I back off, but it doesn't feel comfortable there. Stock (unbalanced) crank, babbitt bearings, 5.2 head, 0.080" over bore. Stay tuned a year as I'm going to install a Mitchell O/D as soon as it comes...
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JayJay
San Francisco Bay Area

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1930 Murray Town Sedan
1931 Briggs S/W Town Sedan
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