i have a 1988 larson contempra with twin 5.0l mercruiser engines and alpha1 outdrives. the port engine has been replaced with a 190 hp car engine. the other engine has 140 lb even in all cylinders. the outdrives have been rebuilt .the boat is from maryland. the props which came with the boat are in good shape,one is corroded and can 't be read the other reads L48-78118-17at full throttle the one engine runs at 2200 and the car engine runs at 3000. the bottom is rough and painted with antifouling paint. the boat weighs 9000lb is 30ft. with a 10'6" beam. the trim tabs work but do not make any difference. my question is if the props haven't changed why will the boat not plane (assuming it did before i got it) is the 190 hp car engine under powering it?(by 30 hp) enough to make a difference or could the outdrives have been rebuilt with different gearing. both carbs are openning full throttle to the stops and the 4 barrels are also opened up at full throttle. what would be my best course of action? thanks dan.
