Rough running after extended running

[Tripaddle]

Well let’s start with I don’t have enough time on the boat to properly do all the maintenance. I change the impeller and oil. Also I add a little Marvel Mystery oil to the fuel. We usually run for less than an hour at a time, maybe even less than 30 minutes. It always seems on the way back it runs rough. Lowering the rpm helps at first but this past weekend it ran rough even when I lowered the rpm. We probably never go above 1500 rpm. The temperature never moved while running at the dock for 30 minutes while propeller engaged. The oil pressure began around the 20 psi mark and increased to 40psi as it ran. It is raw water cooled. I’ve often thought I need to do something to get the temperature higher. I’m not sure the complete history of this motor. We bought the boat after it had been on the hard for 7 years. I rebuilt the carb, replaced fuel tank, fuel pump, filter, and all hoses. I’ve never touched the points in the 4 years we’ve had it in the water of the Chesapeake Bay. When we bought it other than the fuel pump it cranked and ran. It’s in a 1976 Cal 2-27 and the motor looks fairly clean looking. This past weekend we lost all the wind and motored for over an hour. It never cuts off but does worry me that it might. I’ve ordered the tune up kit, coil, springs, and plug wires. I’m sure the points need replacing and springs oiled and inspected. I’m suspicious of the coil after the motor is warmed up. I’ve pumped gas from the bottom of the tank last year and found no water. Even after sitting for months it will start immediately. That’s everything I can think to describe the motor. So would you think ignition is a good start? Should I worry about the motor temperature? Next time I’m using my pc instead of typing all this on my phone!

[Dave Neptune]

David, sounds as if you are on the right path. Give it a thorough tune-up. Lube the C-advance and replace the points, plugs, condenser, coil and wires.

It is a VERY good idea on these old motors to set the "dwell" with a meter as the cam lobes in the distributor are very worn by now. This wear is bad for the points and makes setting without the meter a guess at best. However with an EI the "dwell" issues are long gone and tuning will be in the past.
A great idea if the budget permits.

Dave Neptune

[sastanley]

David, How often do you use the boat? In the mid-Chesapeake growth on the prop is a HUGE problem. The boat sitting for extended periods (a few weeks!) can let junk grow on the prop.
I highly recommend you get the prop cleaned and report back. I have resorted to short hauling my boat mid-season in early August a few (several) miles north in Solomons, MD, so I do not get frustrated with the engine running poorly with a fouled prop. I keep my boat in a "clean marina", I don't think I can hire a diver and follow the clean marina guidelines. I have no idea what your situation is where you are, but get I recommend you get the prop cleaned without wasting time on other stuff first and let's go from there.
You have a lot of issues going on..I am just trying to help isolate. All of Dave Neptune's suggestions are good too..just don't blow lots of money until the prop is 100%..

[ArtJ]

https://moyermarine.com/product/ignitor-electronic-ignition-kit-late-model-iglm_13_195/

A Ignitor upgrade would be a great improvement easy swapout with points

This is for late model A4 There is also a Early model kit

Best Art