Hello Woodyboaters, when I went out for my first run, my 331 Hemi only gave me 1500 rpm at max throttle.
I did various things to correct the problem: changed the plugs, changed the electric fuel pump and even tried some additives to help compression. My first compression test gave me readings in the 60 – 80lb range. So, thinking that maybe some rings were sticking because it sat for a season or two or that it needed some lube to loosen things up I tried that Marvel Mystery Oil. I put some in the cylinders and in the fuel. After doing that I was told that I might have done the compression test wrong the first time. I did it with the other plugs in and the throttle wasn’t wide open. So I removed all 8 plugs and opened the throttle and did the test again and then got compression readings in the 150 – 160 lb range. Before putting it away for maintenance, the ranges was in the 110 -120 lbs or so.
After doing all that, I finally figured out that one of the carbs was clogged. I unclogged it and now it runs like a Hemi should. However, now the boat porpoises at high speed. If I push it over 3300 RPM it starts to bounce and it gets progressively worse. Any more RPM and I think I may bounce it out of the water. I’ve had this 22′ Shepherd since 2007 and It NEVER did that before. I used to get 3800 RPM or so and about 40 mph. Now anything over 3300 and it’s Mr. Toad’s Wild Ride.
Could my Mystery Oil have increased the compression above what it used to be? Am I getting more power at 3300 RPM and lifting that boat out of the water? Any thoughts? You know of anybody in the hobby that may know?
So to help our readers, I did ask these questions.
1. New Prop? NO
2. Hull been worked on? – NO
3. Engine moved? – NO
4. Hull damaged, sitting wrong on a trailer? – NO
5. Have you thought of just changing the name of your boat to FLIPPER and move on? – NO
So there ya have it. A true Woody Boater question.