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Posted by MoparNorm on Friday, February 15, 2008 at 18:57:25 :
In Reply to: Re: Difference between Industrial versus automotive engines posted by Kaegi on Friday, February 15, 2008 at 16:29:34 :
From the factory Service Manual.
1&2 have the same compression, 3's are less.
1&2 have higher rpm rating, 3 is less.
2&3 have roller chains driving the cam.
2&3 have smaller rod journals.
2&3 have great end play tolerances.
2&3 have Tri-metal main bearings.
2&3 have great main bearing clearances.
2&3 have high performance oil pumps and operate at higher oil pressure and volume.
2&3 have 1 qt. larger oil pans.
1&2 share valves composite.
2&3 have smaller valve diameters.
2&3 have positive valve rotators.
2&3 have hydraulic lifters.
2&3 have smaller vale springs, but higher spring pressure.
The same FSM, only lists a 251-3, so the series 1&2 may have been dropped by 1963.
Compared to the 225 of that year, the 251 is bullet proof with hardened valve seats and stronger alloy components.
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