Misfire at high RPM

[Oday32-CC-LA]

Hey all,

I am kinda new to the Atomic 4 and for that matter to working on engines overall. Therefore, please excuse if the following question is simple or stupid

A couple months back I bought my first sailboat. The Oday 32 is sailing nicely, but I have some issues with her engine.

After some engine tune-ups, the engine starts nicely and runs smoothly in low RPMs. However, if the engine speed is increased the engine starts misfiring.

Troubleshooting the problem, I think we actually have the firing order wrong. Based on what I read, the firing order is 1-2-4-3 CW, but we set it CCW.

Question 1:

Is the firing order and direction the same for all Atomic 4s?

I tried to adjust this, but can't get the engine to start anymore then. So I am wondering why that is.

Question 2:

Why would the engine start nicely and run smoothly in low RPMs if the firing order is wrong in the first place?

Question 3:

Is there an easy way to set the timing perfectly? Like, can I somehow measure the timing until I have the most perfect setting, instead of just turning the distributor by hand till I think it is perfect?

Can anybody help me understand this better?

Thank you all!

[Dave Neptune]

#1 yes

#2 these engines are not real fussy

#3 A~perfect with much difficulty if you are unfamiliar with fine tuning.
B~will run fine setting close pretty easy with some guidance
C~ will run OK or pretty good setting it via power timing.

It is a choice.

If the distributor is wired backwards it will run on 2 cylinders as they will be in the same spot.

Dave Neptune

[Mo]

Agree completely with Dave. Couple of things that come to mind.

Have a look and see if there's a sheen on the water behind the boat where the exhaust comes out...that might indicate a bad plug or wire.

Another thing that comes to mind is the springs under the distributor cap. They are the centrifugal advance for timing as rpm increases. It's a good idea to have a spare set of those hanging around (you can get them at MMI). Once a year if you spray them with some rust prevention lubrication they are generally trouble free.

[tenders]

The way to check the firing order of a running engine is to pull the wires off the plugs one at a time. (Wear rubber gloves and keep your fingers away from the opening of the plug cap.) If the engine RPM changes, that plug was doing its job properly. Put it back on and try the next wire. If the RPM doesn't change, it wasn't working correctly. If you find two that aren't working, maybe switch them and see what happens?

I'm not sure if a sticking centrifugal advance will actually cause backfiring, but it is certainly worth checking.