Re: Video troubleshooting
Air intake for that engine is right under the carb. You almost put your hand on it when you reached in the video. Under the carb you will see a flat plate held on by (usually) two hex head 1/4 inch bolts. It is a combination silencing plate and following sea baffle to prevent water from entering the carb on a rapid slow-down where water might come over the transom. Take the bolts off and remove the plate. check to see if the silencing foam inside the plate has swelled and is partially blocking the openings or if some crap has gotten caught in it.
I used to (Still Do) run mine without the plate. That is a sweetheart of an engine and in its day was a strong 55. Mine used to beat the 3 cylinder OMC 55s. I probably have thousands of hours on it now.
Hint: The starter motor tends to break the top boss on the block due to side thrust laods while starting. These bosses are part of the front engine block so are not replaceable if broken. To prevent this from happening fabricate a steel plate to fit behind the bosses (all three) and reinforce them. Chrysler used to offer this plate but I don't know if it would still be available. Try Franzmarine over at The Chrysler Crew. If the top boss has already broken, the steel plate will fix it and you can carefully drill a small hole in from the side and tap it for 8-32 to hold on the broken piece. Welding here is not really an option.
Your engine sounds like it is running well in the barrel, but the only real test is on the water. If your boat is 15 foot, it should get about 25-27 MPH with you alone.
