1991 OMC Cobra 2.3L - can't reach max rpm

[Smiles79]

I've got a 1991 VIP Vision 17ft with an OMC Cobra 2.3L. First time I had it out on the water, I couldn't get it to go past 2000 rpm. I pulled the carb off and rebuilt it, but noticed that the float was set all the way down (other than that it seemed fine). I adjusted it properly, re-installed, and now the boat starts and runs better but I cannot get past 3200rpm or so. The prop is a Solas 2411-133-17, which as I understand is a 17 pitch and acceptable for this motor. Initial timing is about 9 or 10 BTDC. A couple thoughts I have:

Maybe the previous owner tried tuning the carb with the float incorrectly set and now it's all out of whack.

Maybe the mechanical advance in the distributor isn't working properly. It moves freely and snaps back into place, but I'm not sure how much it should be able to move. Link below with a video

The hose barb port on the fuel pump that runs back up to the carb has gunk in it. It seems like this port is mostly for safety in the event of a diaphragm failure. If this port is plugged could it prevent the pump from pumping enough fuel to support higher RPM?

Any advice is greatly appreciated!

Edit: The boat seems to wind up fine when not under load

https://imgur.com/knxDGdZ

 

[Bondo]

Ayuh,..... All things considered, I'd do a compression test next,....

 

[kenny nunez]

If your engine has a spin on style fuel filter it will be a good idea to get a replacement filter. Are the spark plugs new? A good time to do as Bondo said to check the compression. The Tygon hose has nothing to do with fuel pressure and as you mentioned it is there to save the boat from a fire should the pump start leaking.

 

[Lou C]

That’s a centrifugal advance distributor and you should check it with an advance timing light to make sure you’re getting full spark advance at the specified rpm. If you don’t have a manual I can look it up in my OMC shop manual.

 

[Lou C]

Check the ignition system first then move on to the fuel system, if you run it on a separate outboard tank it can help sort causes out.

 

[Scott Danforth]

will second both above...... compression and ignition

what are the compression numbers?
did you service the points and set the dwell on your ignition? did you then set timing?

 

[Lou C]

Here are the specs for the 2.3 Ford:
compression: 165 psi
plugs: Motorcraft AWSF-32 or Champion RS12YC
gap: 0.035"
point gap: 0.018"
dwell angle: 36* + or - 2*
timing: 10*BTDC total timing advance @ 3400 rpm = 34* (10* base + 24* centrifugal advance) to make it easier to check:
@ 2000 rpm you should see 20* total and at 3000 rpm you should see 30* total
idle speed: 600-650 rpm

with old boats like this it's tough, there is so much old stuff you wind up having to go through everything. Ignition system, carb, fuel pump, boat fuel system (tank, anti-siphon valve, pick up tube etc).

under the plate that holds the points, you will find the weights and springs for the centrifugal advance unit, these should be inspected to make sure they aren't sticking, they can rust up and limit your total timing advance. I "think" that is a Mallory unit judging by the pic
The Prestolite units have a lubricating wick in the distributor shaft that you put a few drops of oil in each season; this keeps the weights/springs lubed and moving freely hopefully. Not sure if the Mallory has the same thing.

that's all I got, hope that helps.

 

[Smiles79]

Thanks everyone for the help. I will get a compression tester and some new plugs. I will also verify that the timing is all in like it's supposed to.

 

[Scott Danforth]

before you worry about timing, you must file the points, rough gap the points, and set dwell with a dwell meter.