The manual on my KE2500 says 4 degrees for the manual and 8 degrees for automatic. I set my manual at 8 and it runs much much better than at 4.
Also take into consideration the altitude where you live, and advance 1 degree for every thousand feet of elevation~!
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Red Rocket: Stock 1971 GMC KE2500, LWB, Custom Camper, 4x4, 350 V8, 4 bbl, 4 speed
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