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

[F_R]

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

When the vacuum is high enough it closes the switch, connecting the center terminal to the aluminum switch body. However, the aluminum switch body is mounted on plastic, so closing the contacts didn't actually ground out the center terminal. In other words, it did nothing.

Enter the safety switch. At slow throttle settings, it grounds the vacuum switch body. That completes the circuit between the center terminal and ground (at high vacuum and slow throttle). Advance the throttle, the safety switch opens, ungrounding the vacuum switch body, and it can no longer function.

This may be the wrong motor, but you can get the idea.

 

[sojo81007]

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

I put the engine in my test tank, totally disconnecting the safety/vacuum switches. It didn't change anything - the problem isn't there. When I removed the flywheel I noticed the one coil has a nick on the top of it...don't know if it's been damaged, but I was having problems with the bolts on my wheel puller and I threaded the one down pretty tight. I'm assuming I hit the coil when I did that (can I damage anything else!?!?) Apparently, yes.

The flywheel key's edge has been rounded off, like it was trying to spin. I'm assuming that it didn't spin completely, because the key was not completely shorn off. I have included pictures, hoping for someone with experience to give advice as to whether I should replace the flywheel key or continue using this one. I do think I was hasty in replacing the flywheel, so it could be that it wasn't on dead center when I slid it down over the shaft. I did use acetone to clean both the flywheel hole and the taper on the crank shaft.

I test the plug wires with an OHM meter - all ok.

I pulled both coils and found that I had NOT inserted the wire far enough...it was sitting at an angle which was obviously too sort, and there was carbon all over the hole in the coil, indicating that spark was indeed jumping. I feel really dumb, knowing that all of this was because of my lack of paying attention...I never checked that wire again, because I was SURE that I had put it in really well. I checked the other one because I had my doubts. How about that!?

I did an OHM test on the coils (one lead to the spark plug wire prong and another on the green wire) and they read 7.6k and 7.8k. Are those two numbers close enough? Also, do you think I need to replaced the coil with the nicked housing, or can I simply fill it in with some insulating varnish/goop - it doesn't appear to be broken through, at least as far as I can see.

 

[steelespike]

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

If the flywheel key is damaged (partly sheared) it throws off the flywheel magnet timing.
A new omc key is needed.Check the keyways for damage.Be sure to torque the flywheel nut correctly.100-105 ft lbs.
Shaft and bore clean and dry.
The nut keeps the the flywheel in position. The key positions the flywheel correctly.

 

[sojo81007]

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

Here's a picture of the inside, not sure how well you can see. It did seem to have a small nick on the side. I will order a new key.

 

[jbjennings]

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

If I had to guess, I'd say the problem is an improperly inserted plug wire going into the coil (done it myself more than once). Don't use a hardware store woodruff key---they will shear. Go with OMC or equivalent. I doubt the nicked coil is the problem if you've Ohmed it out and it's the same as the other one. BTW, I assure you the universal magneto when working correctly will fire that motor up so easily you won't be able to tell the difference with the fancy electronic ignition. -just my opinion. I'm biased, though. I like the old simple stuff.
Hope you get it going!
JBJ

 

[HighTrim]

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

The coil should be fine. Seal it though with something though to prevent water from damaging it in the future.

You always want to twist the wire into the hole as you push it in. This ensures better contact and ensures it holds.

 

[Vintin]

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

I recently replaced the coils in my 1957 Johnson 35hp and the new coils from NAPA ($23ea.) had threads like a screw where the wire attaches. Instead of 'screwing' the wire into the coils I 'screwed' the coils on to the wires. I only pulled about three inches of spark plug wire through the ignition plate this way Vs. having to pull the whole wire through using the rotate the wire method. You might want to take a close look the vacuum kill wire and trace it from the bottom cylinder set of points to the vacuum module as this wire moves with the plate and may have lost some insulation along it's path.(long shot, for sure)

 

[sojo81007]

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


I've got the wires properly seated in the coils, everything is bolted back together. (I wrapped the kill wires in electrical tape just to be sure there was nothing going on with them.) I've checked and rechecked the integrity of each wire and coil. Should be good! The coils are not sticking out past the bosses either

My only question is the key...this one appears different than the last - though the dealer and I both checked that it was the proper part. I've attached a picture of the new key inserted in the shaft...does it look ok? My OEM manual just says that the outer edge must be vertical. That's pretty much it...The small mark they talked about wasn't there...only two small indents on the one side. I had to lightly tap the key to get it to go in, it's a tight fit. If I make the bottom of the key flush with the taper on the shaft, the top side sticks back at a weird angle. Any advice...I've nearly every mistake possible on this project so I'd like input before I throw the wheel on there and mess something up.

 

[kfa4303]

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

Hi sojo. Glad you're getting her put back together. The flywheel key (aka woodruff key) looks good to me. As you said, the straight edge should be vertical and inline with the crank shaft. Because the shaft itself is tapered on one end the key will be proud in that area. You should be able to raise and lower the flywheel on and off the shaft without disturbing the key. Try lowering the flywheel then rotating it clockwise by hand with the spark plugs removed. If the flywheel spins freely and doesn't rub against the coils, you can then tighten the flyhweel nut a bit and test for spark. Once you have a good strong spark from each plug, you can tighten the flywheel nut to fully and fire her up.

 

[jbjennings]

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

I also think the key looks fine. If you can get the flywheel over the key, the key will be forced to match the inside of the vertical slot of the flywheel. It's not important to have the key sitting perfect in the slot on the crankshaft as far as I know. It looks a wee bit out too far on the top of the key so that the key would snag on the flywheel when you try to put it on, as far as I can see. You'll probably have to get it vertical so the flywheel will slide down on it fully, but if you get it down over the key, I believe the flywheel will self-right the key in the slot perfectly when you torque it down.

 

[sojo81007]

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

Ok, thanks! Hopefully I'll be able to get in the garage on monday (my day off) and get it put back together. I hope to throw that little 1970 Evinrude Mate I just bought on the boat and head to Raystown.

 

[sojo81007]

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

I think this begins my kayaking career.

Was putting the flywheel on and pulled the plugs out so I could turn the flywheel without compression and listen for anything hitting underneath.

Both plug holes were stripped. Apparently when I was lying on the dock, reaching out to change the plugs on the water, I exerted too much force and over tightened the plugs. (I have never done that in ANYTHING) This is unbelievable. !

I went to Advance and got a thread saver kit, I tapped it very slowly and used plenty of grease to keep any shavings out of the cylinder. I also used a shop vac with a small hose attached to get down in the cylinder and vacuum after I tapped the hole just to be safe. When I moved to the bottom cylinder something happened along the way and the tap started going in crooked. I tried everything I could but it kept getting worse.

Here's where I quit! I'm not usually a quitter, but I've done so many stupid things on this project that I'm going to have to stop. The problem is that I can't afford to take it to the marina for work, and obviously I cant afford to do it myself (and can't even get it done!).

If anybody's interested in a 1968 Whaler I might work out a good price!

 

[nwcove]

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

dont give up now!! you can pick up a head cheap, and a gasket is no huge expense! we all learn from our mistakes.

 

[HighTrim]

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

Agree with Tim^^^^

Just get a good used head, much easier and quicker than tapping the holes if you have no experience doing it. Go to aomci.org and place an ad in the webvertize. Should be able to get one cheap, if not, PM me.

 

[sojo81007]

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

Ok, I did post such an ad. A new cylinder head is $190 :faint2: Would a used head have to be resurfaced or anything? I checked my manual and it does give the torque specs and pattern so I should (ha! ) be able to get that right. The thermostat has been removed, along with all the other parts, so if I could find a used one with those things in it it would be great.

 

[nwcove]

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

$190 for an NOS head is to much. you could probably get a complete parts motor for that. a used head should be checked for flatness, but thats a job you can do at home for just a few bucks. just treat the head as if it were made from a soft metal like aluminum tho!

 

[sojo81007]

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

A parts motor is a great option too. I'll begin that search as well. So glad this isn't in the middle of summer!

 

[HighTrim]

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

Ill look for you. Hopefully someone local to you can help though.

 

[sojo81007]

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

I buy and sell these old motors as a hobby and so I hope to find a big twin. Even if I find a head elsewhere I'm going to snatch up the first 40hp for myself. Thanks for looking, let me know if you find anything!

 

[kfa4303]

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

Look on ebay. You should be able to find a head for <$50.