Hi. I am hoping someone has a clear idea that matches one of the many hunches I have about my engine. I don't want to start tearing everything apart to find a simple problem. Here goes:<br />1. Merc 350/260hp stated to run at 4200-4600 rpm in the repair book. Mine runs 3800-3900.<br />2. I have a '85 Chris Craft Scorpion, (like the Mach 1 Condor, or Nova, and enless other styles.) Comparable boats at the marina are running mid to high 40mph's. Last season, I started out with a stainless 14.25x19, and was running around 45-46mph at beginning of the season. A month later I was running 40mph. I ding'd the stainless, replaced it with 14.25x19 aluminum, and dropped to 38. This is understandable, but I have never gotten my rpm's over 4000 yet.<br />3. I tried a 14.25x17, and I gained almost 2000 rpm's, bringing me back to 3800rpm, but dropped my speed down to 34mph.<br /><br />OK....Now this year...I am back with the aluminum 14.25x19. I run 37-38 mph, (these are all GPS numbers,) at 3700-3800 rpm's. It takes quite a while to get out of the hole, and if I have four three other people in the boat, at least one of them HAS to join me at the windshield, or it will never fall onto plane. I almost feel like the throttle cable stops before the carb's WOT, but it is not the case. I removed the line, and it was as far as the carb would go also.<br /><br />This 350/260 Merc. was replaced a few years back, and sounds like it runs like a top. I did a tune-up this spring. Last year I did run into some problems with the module in the distributor. It wouldn't fire under load properly, so I cleaned the contacts of a little corrosion, and it ran fine after that.<br /><br />My suspected causes: 1.carb (which is a 4bbl Weber) just sucks...(no pun) 2. Intake gasket has a small leak somewhere 3. That module needs a replacement instead of a cleaning. 4. I'm biffed, and I should just suck up the fact that I have the slowest scorpion out there..hehehe.<br /><br />Any help on ideas would be great.<br /><br />Oh yeah..one more thing. I was re-greasing the U-Joints this spring, and I noticed that the shaft seamed awfully hard to turn. Now, I have never turned a Merc shaft before, so I don't know what it is suppossed to feel like, but it was a two-handed event, and you could hear what I am guessing was the impeller groaning. I did have the lower unit replaced last year. Is it supposed to be that hard to turn the shaft for the outdrive?<br /><br />Thanks,<br />-Gary
