1966 Evinrude Big Twin 40hp Running on One Cylinder...but has spark at both plugs

[sojo81007]

On a recent trip to the lake my Big Twin began running on one cylinder. This happened at the dock, and it had run fine on the previous trip several weeks before.

I checked spark, and it seemed that the top cylinder had none. I pulled the flywheel and found that one of the coils was broken in pieces, and that the pieces had gone everywhere. I cleaned it all up and replaced the points, condensors, coils, wires, and plugs, giving my old outboard a completely new ignition system.

When I set the points I turned the crankshaft so that the keyway was in line with the rider/riser on the points and set them to .020.

I took it to the lake and it is still running on one cylinder. Both cylinders have spark when I do a visible spark check. The spark plug on the top cylinder is wet with fuel, the bottom one is dry. It will not run on the bottom cylinder alone, but will run when the bottom is unplugged and the top one is doing the work.

I checked compression and both cylinders are putting out 118/119psi, so all is well there.

Any ideas as to what could be going on? I suspect it could be the reed valves, a fuel pump, something I did wrong in the ignition system? It seems though that the lower cylinder isn't getting any fuel.

 

[kfa4303]

Re: 1966 Evinrude Big Twin 40hp Running on One Cylinder...but has spark at both plugs

HI sojo. Welcome to iboats. It definitely sounds like you're dropping a cylinder. However, your description is a bit strange. If when you drop a cylinder you should expect that the spark plugin that cylinder would be wet due to lack of igniting the fuel. You should also be able to pull the spark plug wire off of the the "dead" cylinder without altering the rpms of the motor. However, if/when you pull the wire and the motor dies/drops in rpm then you know that cylinder was, in fact, firing. I would repeat the test again just to be sure which cylinder is at fault. Also, be sure to test the plugs with a proper spark plug gap tester, rather than grounding it on the block. You can get one at any auto store for about $2. Your spark should be capable of jumping a 1/4" gap with ease. Make sure you're using Champion J6C plugs as well. Here's a great ignition rebuild link with lots of pics too. It's for a slightly different model, but all of the same steps apply to you motor. Holler if you get stuck.

3 HP Evinrude Lightwin Ignition System Tune-Up 1952-1967

 

[jbjennings]

Re: 1966 Evinrude Big Twin 40hp Running on One Cylinder...but has spark at both plugs

On a recent trip to the lake my Big Twin began running on one cylinder. This happened at the dock, and it had run fine on the previous trip several weeks before.

I checked spark, and it seemed that the top cylinder had none. I pulled the flywheel and found that one of the coils was broken in pieces, and that the pieces had gone everywhere. I cleaned it all up and replaced the points, condensors, coils, wires, and plugs, giving my old outboard a completely new ignition system.

When I set the points I turned the crankshaft so that the keyway was in line with the rider/riser on the points and set them to .020.

I took it to the lake and it is still running on one cylinder. Both cylinders have spark when I do a visible spark check. The spark plug on the top cylinder is wet with fuel, the bottom one is dry. It will not run on the bottom cylinder alone, but will run when the bottom is unplugged and the top one is doing the work.

I checked compression and both cylinders are putting out 118/119psi, so all is well there.

Any ideas as to what could be going on? I suspect it could be the reed valves, a fuel pump, something I did wrong in the ignition system? It seems though that the lower cylinder isn't getting any fuel.

Like KFA4303,
I suspect you aren't getting sufficient voltage at your spark plug, or a bad plug. Running low voltage if your coil was going out can ruin a plug, as will an oil fouled plug. You need a spark tester as KFA suggested.
ALso, if you have 2 carbs, the float may be stuck or the carb needs a rebuild on the suspected cylinder. Rarely are reed valves going to be a problem. If your fuel pump wasn't pumping good, squeezing of the primer might give both carbs sufficient fuel to run. If there's a hole in the pump diaphragm, it can cause some goofy stuff to happen, but usually flooding rather than no fuel.
I'd check spark, then carburetion.
JBJ
New fuel lines if they're old.......

 

[sojo81007]

Re: 1966 Evinrude Big Twin 40hp Running on One Cylinder...but has spark at both plugs

I think we're getting somewhere. After the good compression check I pulled the flywheel again and I think I found my problem: ME! I had trouble getting the ignition system back together because I completely took it apart...when I was putting it back together I had trouble routing the kill switch wires. I routed them best I could and put it all back together.

What happened though was that the one wire rose to high off the point and was in contact with the flywheel. That stripped the insulation off of the wire and expose just a tiny bit of wire. That is why I believe I had spark during tests, but the lower cylinder wouldn't run under load - too much of the current was grounding to the flywheel. (And I do believe it's getting fuel because the plug smells of fuel when I check it now.) So, after I get that all fixed I'll report what has happened, but I believe that I'm my own problem!

Thanks for all the help.

 

[kfa4303]

Re: 1966 Evinrude Big Twin 40hp Running on One Cylinder...but has spark at both plugs

Awesome! I've had the same problem before. It can be tricky getting all the wires tucked away. Here's another handy link should you need it.

Reviving a Vintage Big Twin - Part 1

 

[sojo81007]

Re: 1966 Evinrude Big Twin 40hp Running on One Cylinder...but has spark at both plugs

Back to the drawing board Finally got it all back together and headed to the lake. It started right up but wasn't acting quite right. Started out and it would occasionally miss and then shut off. It was only running about 1/3 the speed it should...

I pulled the top plug wire to see if it would start on the bottom cyl. Negative. Hooked the top wire back up and it fired right up and then died and would not start again no matter how much I tried.

I'm quite frustrated at this point. I've done all I know to do and yet I can't get the thing to run! A couple of notes about my inexperienced repair job...I ended up stripping the threads on the set screws from tightening the points during adjustment. I had to tap out the holes, put in new screws, and they seem to hold fine. I also used nail polish around the points to help keep them from moving...somebody said to do this. Any ideas?

 

[jbjennings]

Re: 1966 Evinrude Big Twin 40hp Running on One Cylinder...but has spark at both plugs

I've done quite a few of those universal ignitions and find it best to do the following? totally take the armature plate off the motor. Take the plug wires off, and replace them---or at the very least, cut about 1/2" off the coil end of the wire and make sure you see some good copper. The ends can be corroded and prevent good continuity. ALso, the points have to be spotlessly clean; not even a fingerprint allowed. Last of all, switch the plugs and see if the problem follows the plug. The plug wires should SCREW onto the coil, BTW. I would also change the capacitors as well. They're cheap and a bad capacitor will give weak spark. If you've not gotten s spark tester yet---$6 at autozone last time I bought one---you should get one. The color an size air gap that the spark jumps can tell you a lot.
Good luck,
JBJ

 

[sojo81007]

Re: 1966 Evinrude Big Twin 40hp Running on One Cylinder...but has spark at both plugs

I did replace the plug wires, plugs, coils, points, and condensers. I did have one concern about the one wire...I seemed to have trouble getting it to go into the coil. I will remove the armature again and start from scratch, testing each part to make sure that one of the new parts isn't faulty. If the points are out of adjustment I'm going to try those Atom ignition modules as it seems my skill with setting points is about zero. It seems simple, and I was confident I had the set properly, but I don't seem to be having much success. I'll update once I pull the wheel later today.

 

[kfa4303]

Re: 1966 Evinrude Big Twin 40hp Running on One Cylinder...but has spark at both plugs

Yeah, it can be a little tricky getting the new copper core wires onto the coil posts. Just go slow and twist them on rather than just jamming them in there. The idea is to get the small metal pin in the coil to pierce into the metal core of the wire to create a connection, but it can take a few tries to get it right. Also, remember that while one set of points is opened to .020", the other set should be fully closed. Here are some links to a great series of videos that show a guy rebuilding an entire 15hp from the ground up, including the ignition. He has a funny Yankee accent, but is does a great job with the vids.

Episode 16 - YouTube
17 - YouTube
18 - YouTube

 

[jbjennings]

Re: 1966 Evinrude Big Twin 40hp Running on One Cylinder...but has spark at both plugs

Don't give up on the universal magneto. You will get it right, it just takes a little practice. I've NEVER had to paddle while using a motor with a universal magneto because of an ignition failure. Even if one coil goes out, you've still got the other. THey're a good little system---just need good connections.
When the highest point of the cam hits the rubbing block, set them at .020", for each set. Should be a little friction on the feeler gauge when they're set right, but not a LOT of friction.
They can be annoying, for sure....

 

[sojo81007]

Re: 1966 Evinrude Big Twin 40hp Running on One Cylinder...but has spark at both plugs

Copper core wires? I got wire from the evinrude dealer and I'm not sure if it was copper core of not. It had strands of silverish wires in the middle...wrong stuff?

 

[nwcove]

Re: 1966 Evinrude Big Twin 40hp Running on One Cylinder...but has spark at both plugs

they are the right type of wire, metallic core.

 

[sojo81007]

Re: 1966 Evinrude Big Twin 40hp Running on One Cylinder...but has spark at both plugs

Pulled the flywheel again (weird thing, one of the bolts that holds the manual starter ratchet/mechanism was broken and had a piece of blue stuff in it. Very weird. I did get it out when I threaded the puller in the holes.) Everything look fine under the wheel, no rubbing, chaffing, etc. The lower set of points was out of adjustment so much that I couldn't get a .011 feeler gauge in between them. The other set was fine at .020. Obviously I didn't tighten it enough or something. I guess I was a little shy about tightening those screws after I had stripped out the others...I'm seriously leaning toward installing the Atom points/condenser replacements. I'd much rather have something that doesn't go out of adjustment so easily.

 

[geoffwga1]

Re: 1966 Evinrude Big Twin 40hp Running on One Cylinder...but has spark at both plugs

You really don't need to have the securing screw very tight,just snug enough so it doesn't move but you can still make adjustments.That way you don't have to tighten when you've got the right gap and move it slightly and screw the whole thing up.

 

[sojo81007]

Re: 1966 Evinrude Big Twin 40hp Running on One Cylinder...but has spark at both plugs

If that's true then why do you think the point moved out of adjustment? Could there be something else which is causing it to be knocked out?

 

[sojo81007]

Re: 1966 Evinrude Big Twin 40hp Running on One Cylinder...but has spark at both plugs

An update. I ordered the Atomic ignition modules from Banta in Canada. Installed the per manufacturer specs, put everything back together, and checked for spark. Good hot spark on both. Took it to the lake and it started faster than it's ever started...fired up as soon as it turned over. Seemed to be running smooth, much smoother than since all this started. When I left the dock I hit the throttle to see if it was going to go and it did rev pretty well, and the boat even started planing (it's a Boston Whaler 13' so getting on plane is something that happens quickly ) Slowed it back down and went out to the end of the no wake and hit it...nothing. Would not go any faster at all.

Took it back to the dock and did a cylinder drop test. Runs great on the top cylinder, won't run on the bottom. Switched plugs, same result. Switched the ignition module to make sure one of them wasn't faulty. Both run the top cylinder fine, the bottom won't run the motor (though it had bright spark in the garage.) So obviously we're talking bad plug wires or coils...or maybe the vacuum cut out switch? The safety switch has been disconnected since I got it I believe (didn't even know what it was). Can I disconnect all the wires from this switch to make sure that it's not what's causing the bottom cylinder to not fire when running but fire in the garage?

 

[HighTrim]

Re: 1966 Evinrude Big Twin 40hp Running on One Cylinder...but has spark at both plugs

I would definitely start with the plug wire and coil. have you tested them?

 

[sojo81007]

Re: 1966 Evinrude Big Twin 40hp Running on One Cylinder...but has spark at both plugs

They are all brand new, so no. Weird thing I forgot to mention - a couple of times on the way out to the no wake it surged and then quickly backed off. Felt like a short, or maybe that vacuum switch. It was the first time I had installed those old type plug wires, it's possible that I damaged them when I put the ends on, I suppose.

 

[F_R]

Re: 1966 Evinrude Big Twin 40hp Running on One Cylinder...but has spark at both plugs

Well, matter of fact, the vacuum cut-out switch does operate on the bottom cylinder. Also, the safety switch does prevent the vacuum cut-out switch from working at higher throttle settings. I don't know if that is what is happening here or not, but it is a good guess. People take this stuff off, then pull their hair out trying to diagnose problems when it doesn't work.

Remove the black wire from the center of the vacuum switch and see if the high speed problem goes away. Of course you will have removed the over-revving protection if you do, so best to put stuff back together like it belongs.

 

[sojo81007]

Re: 1966 Evinrude Big Twin 40hp Running on One Cylinder...but has spark at both plugs

I plan on starting with that before pulling the wheel for the fourth time. The threads on a couple of the holes are really worn...(more of my many mistakes....this poor outboard is my guinea pig!) I'm thinking, and hoping, that the vacuum switch is the issue. If I remember right, there is the black wire and another wire that goes to the center post of the vacuum switch, and then the other switch comes down to the top right of the switch.

On a side note, I was thrilled with the operation of the ignition modules....that thing never started that quickly, and it was running so smoothly that it had me fooled...I didn't realize the one cylinder wasn't running... If the NOVA IIs are similar I'm going to order a few and keep them around. If one ever went bad on the water it would be a 5 minutes fix and good to go. Sounds good to me!