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<blockquote data-quote="Super Dave" data-source="post: 1095572" data-attributes="member: 8429">Originally it was 61ci.&nbsp; 74ci didn&#039;t come along until 1941, although ramping up for it, the 1940 heads had larger ports.&nbsp; The stroke of a 61&quot; is 3 1/2&quot;, a 74&quot; is 3 31/32&quot;, and an 80&quot; side valve is 4 9/32&quot;.&nbsp; Compared to a late model Shovel/Evo 80&quot;, which is 4 1/4&quot;.&nbsp; There was never a factory 80&quot; Knuckle.This is bored .070&quot;os (same as .010&quot;os for an 80&quot; shovel) to the tune of 3.5125&quot;.&nbsp; The flywheels are from a UL, making the stroke 4.28125&quot;.&nbsp; That makes it a 82.9&quot; motor, or as the old guys say, 83&quot;.&nbsp; This motor still has the smaller taper, stepped crankpin.&nbsp; The hot tuna, back in the day, was to machine the smaller tapered holes in the flywheel offset, and use a 1941 and up 74&quot; crank pin.&nbsp; I thin it makes the stroke enough that it is 86&quot; then.&nbsp; This is a real life, &quot;old school&quot; stroker, long before S&amp;S or T&amp;O were making flywheels.&nbsp; These are shaved very thin.&nbsp; Neato!&nbsp; It also has &quot;lightning&quot; gears in the gear case.&nbsp; All drilled out with neat little holes.&nbsp; Very cool.&nbsp; XA rods are also .030&quot; longer than the late model stuff, so the leverage factor is greater.&nbsp; Sorry, I could go on and on.&nbsp; I&#039;m a motor nerd.&nbsp; Adam&#039;s out there getting ready to fire it off now.&nbsp; Better go help him!.</blockquote>

[QUOTE="Super Dave, post: 1095572, member: 8429"] Originally it was 61ci. 74ci didn't come along until 1941, although ramping up for it, the 1940 heads had larger ports. The stroke of a 61" is 3 1/2", a 74" is 3 31/32", and an 80" side valve is 4 9/32". Compared to a late model Shovel/Evo 80", which is 4 1/4". There was never a factory 80" Knuckle. This is bored .070"os (same as .010"os for an 80" shovel) to the tune of 3.5125". The flywheels are from a UL, making the stroke 4.28125". That makes it a 82.9" motor, or as the old guys say, 83". This motor still has the smaller taper, stepped crankpin. The hot tuna, back in the day, was to machine the smaller tapered holes in the flywheel offset, and use a 1941 and up 74" crank pin. I thin it makes the stroke enough that it is 86" then. This is a real life, "old school" stroker, long before S&S or T&O were making flywheels. These are shaved very thin. Neato! It also has "lightning" gears in the gear case. All drilled out with neat little holes. Very cool. XA rods are also .030" longer than the late model stuff, so the leverage factor is greater. Sorry, I could go on and on. I'm a motor nerd. Adam's out there getting ready to fire it off now. Better go help him! . [/QUOTE]

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