Ok I'm thick headed. I have a 1988 2160 trophy. Stock gm 305 5.0 was pulled and replaced with gm 350 5.7. Omc cobra outdrive gear ratios were different for each engine, maybe 21/14 upper and 1.42 lower for the 5.7, and 21/13 upper and 1.5 lower for the 5.0.
So I'm running a 15x15 four blade stainless. That got me to 4,200 rpm wot w/ the tired 305. I know I may have to re-prop to adjust for the gear ratio difference. But I don't comprehend the mechanics of the gear ratio difference.
I presume I may have to increase pitch. Is this right? What about size? Three blades perhaps?
Help me understand the dynamics...all I get is the 5.0 cobra was geared for more torque than the 5.7 cobra and I know I have a prop which seems to increase the torque for the standard 5.0 cobra.
I run heavy with gear and souls. &@$! bodies weigh more than the souls.
Thanks for any insight.
Jarrett
So I'm running a 15x15 four blade stainless. That got me to 4,200 rpm wot w/ the tired 305. I know I may have to re-prop to adjust for the gear ratio difference. But I don't comprehend the mechanics of the gear ratio difference.
I presume I may have to increase pitch. Is this right? What about size? Three blades perhaps?
Help me understand the dynamics...all I get is the 5.0 cobra was geared for more torque than the 5.7 cobra and I know I have a prop which seems to increase the torque for the standard 5.0 cobra.
I run heavy with gear and souls. &@$! bodies weigh more than the souls.
Thanks for any insight.
Jarrett
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