My father and I purchased an old fiberglass airboat with a 292 Chevy inline 6. After replacing the wooden prop with the Whirlwind dad was running on his 350 at the same pitch, and adjusting the angle of the 292, the boat refuses to come on plane. We even installed a trim tab to try to help, but it still looks like a river barge. We have adjusted timing, cleaned the carb, replaced cap/rotor/coil/plugs/wires and still nothing. Plus the damn thing keeps eating tachs. Can you help? Right now it hits only 2400rpm.