3600RPM wall
 

Guys I hit a wall with the formula. Its a 233ls with a omc 260 (350sbc) and an omc stringer 800 drive turning a stock 14 1/2 x 19 3 blade aluminum. She goes to 3500rpm's and just stops dead... She will rev fine when not under load but when she's in gear not so much. Its also giving me issues idling in gear. Idea's???

When you say it "just stops dead" do you mean it shuts down and quits or it just won't rev past 3500 rpm under a load? I suspect the latter and that being the case I suspect...1. Timing not advancing due to an ignition/distributor problem or
2. The carb is starving for fuel due to A. Pluged fuel filter or line or B. Needle valve/Float issue.

To check for distributor advance get a timing light with a dial and watch the timing while you rev the engine to 3000 rpm. You should see a total advance of around 30~32 deg at 3000...if not start looking to a distributor problem.

The carb might be gummed up due to sitting up with ethanol gas that has separated...re-build or replace the carb. If carb is ok look to your water separator for stopage or an inline fuel filter.

Also run a sample of your fuel into a jar and look for water in the gas....also consider adding a bottle of Lucas gasoline stabilizer to your fuel tank. It certainly won't hurt anything and if you suspect a gas quality problem it will probably help it. I run it in mine.

Good luck with this.

sprink I'm pretty sure your the all knowing God of old formula boats hahahaha. She is hitting a wall @ 3500-3600rpm. Not quitting. Based on blacked/carbon gunked plugs (I just dropped in bosch platinum and you should see my very bloody hand) the engine is running WICKED rich. So I'm going to go with fuel supply=good. Timing... I guess I need a timing light and fuel stabilizer. I'll get both in the next few days and report. How can I adjust timing? How do I know if the vacuum advance is working?

Adjust the timing by loosening the hold down clamp at the base of the distributor and turn slowly to advance or retard timing, get it where you want it based on lining the light strobes up with the timing mark on the harmonic balancer. Tis is done with the engine running. If you are not familiar with this...get help from some one that is.

If you are running rich you might still have a stuck needle valve or float...flodding the carburetor.

My bet is ignition...timing, cap, rotor or wires.

I adjusted the timing to what seemed the best running at both WOT and idle. She still hits a wall at 3600. Local marine tech thinks fuel line collapsed/clogged fuel screens??? Fuel filter is new and clean? Lost reverse all together...

I see here it is an 800 series drive. Does it use points and condenser, or did it and it get changed to electronic? (You should not have an automotive type vacuum advance distributor). OMC updated the 400/800 series drive with a "shift assist kit" this helped with shifting. There are two different modules (looks like a power pack) one is for points and the other is for electronic ignition. So this system has two micro switches that are utilized when shifting that all goes thru the module. So these components are very sensitive in the fact they will only work properly with their counter parts, you can not mix and match. If you are having problems with reverse this is a good sign that thing have not been right for a while. Pictures say a thousand words, post some of you distributor and shifter quadrant to help identify what you have.

Neutral safety switch?.They are are usually 3500 RPMs.On newer Mercury they go into guardian if in Neutral or switch bad

Its an old,OMC stringer system, 81 to be exact

@mrv, I'm not sure what kind of pictures your meaning? It does have a non vacuum advance points style dizzy and coil...

You could simply take the "blanket" approach and replace all of the interuptor switches in the system. sounds like you need to find a good old school OMC mechanic in your area that can guide you through this problem. As time goes by and since these drive systems have not been manufactured in 20 + years, it's not going to be easy to find resources on this equipment...but with a bit of research it can be done.

Try searching for an OMC Stringer Drive forum online.