1973 Evinrude nightmare!

[UK Vintage]

Hello,

I have a 73 Evinrude Fastwin 20 which is rapidly turning into a total rebuild, just can't seem to get it to run right so I got a few queries which I could do with some help with.
It starts relatively easy but it splutters and runs lumpy thereafter. Plugs are quite oily which would suggest a rich mixture or its not burning properly. There is also a lot of black sludge floating in the test tank (and also on the gearbox) after running it and when you leave it on the stand after testing the sludge drips from the exhaust. Piston rings seem ok.

Here's what I've done so far:

New head gasket

New impeller and plate

New thermostat

Haven't done a compression test but the compression seems ample (thumb over spark plug hole test)

1 new coil


I also have an identical Johnson equivalent of this motor (which runs very well) and I have swapped the carb from the evinrude to this and it runs fine so I don't think it's the carb, have also swapped the cams over so I don't think it's timing unless the crankshaft is different because I'm using the magneto and flywheel from the Johnson on the evinrude and they did have different ignition systems originally, the evinrude had the external coil system with the one driver coil on the armature plate, with two flywheel magnets and the johnson had no external coils and two driver coils on the armature plate and one flywheel magnet. I have checked the position of the keyways at tdc on both cylinders on both engines and they seem to be in the same place. Can't see any differences in the armature plates either. The flywheel with two magnets has one of the magnets in the same place as the flywheel with one magnet so that shouldn't be an issue i'm assuming. Have also swapped fuel pumps which made no difference.

So I'm running out of ideas and before I take the intake manifold off and incur more gasket fees I thought Id try here.
The head gasket I used was a sierra aftermarket one which said not to use sealer, which I didn't and my dad is an auto mechanic and he seems to think that I should have used sealer and the problem is the head not sealing so would that cause my symptoms?


Thanks for your time any questions please ask

 

[F_R]

Re: 1973 Evinrude nightmare!

This rough running, is that at idle or all speeds, or what?

Crud in the barrel is normal--ignore it. So is smoke. If smoke gets sucked into the carburetor, it will run lousy.

The head gasket does not need sealer. If it is leaking, the head must be warped. Is water getting into the cylinders?

Pull the hose off the upper bypass cover and let it drain overboard. Does that make it run better? There's a story behind that feature.

Has the motor been overheated? You might have scuffed pistons.

You have been into so much stuff on it, I don't know where to start....

 

[floatingwoody2006]

Re: 1973 Evinrude nightmare!

why only one coil? did you clean the points up when you were in there? new spark plugs yet?

 

[tashasdaddy]

Re: 1973 Evinrude nightmare!

first get the right flywheel back on the motor. they are totally 2 different magneto systems. i agree 99% carbs, and linc n sinc. these are simple motors, you are making it hard. thumb, is no way to test compression, borrow a guage. if you are going to try to service you own motor you have to have the basic tools, compression guage, spark tester, ohm/volt meter.
you have fixed jet in the bottom of the carb bowl, and an adjustable slow speed needle, which has to be adjusted on the water, not in a barrel.

read the top secret threads at the top of the forum.

 

[UK Vintage]

Re: 1973 Evinrude nightmare!

Hi F_R,

It is rough at all speeds! Had the head skimmed so I would hope it isnt warped, can't see any water in the cylinders. The return hose interests me because it seems like it's overfuelling, I will definitely be checking that. The motor may have been overheated as the thermostat was knackered and the head was full of salt when I got it, the pistons do look a little scratched (no worse than the johnson though) but no major scores and they are well oiled, bores are better than the pistons. The pistons on the johnson were definitely drier, which says rings to me but the rings (or what I can see of them through the ports) don't look any different from the johnson ones.

Hi Floating Woody,

I replaced the one coil because it had died, it's not the points either as they work fine on the johnson as do the plugs, which are new, not brand new but new!

Hi Tashasdaddy,

No can do on the flywheel I'm afraid, have no external coils and don't fancy paying twice the price for them as the driver coils that the johnson uses. I see no reason why these motors would be timed differently and the tests that I have done (observing points, crankshaft and cam at tdc) would seem to suggest they are the same, if anyone can say definitively that they are then please speak up and save me some time! Having said that it does seem like a timing/flooding issue. Can't afford to buy tools and no-one I know has a compression tester. Things are expensive and difficult to find over here, I'm working on making a compression tester though.

Thanks guys

 

[jonesg]

Re: 1973 Evinrude nightmare!

I feel as frustrated as you and I'm just reading this stuff !

doing it by the numbers takes all ( well almost ) the frustration and needless expense out of servicing engines.
1.Compression test first, with a real guage.
2.Then spark test with the proper gap tester, buy or make one.
3.Then if the ignition is set up properly , its got to be fuel delivery.

 

[UK Vintage]

Re: 1973 Evinrude nightmare!

HI Jonesg,

Thanks for the reply, if it were down to the ignition (plug gaps, points etc) surely the johnson would run the same, they are identical but the johnson runs well, same goes for fuel delivery as I have swapped the carbs over. How do you make gap testers please?

 

[UK Vintage]

Re: 1973 Evinrude nightmare!

Hello,

Does anyone know of any way to get a bigger spark from plugs or is there any plugs that will give me more of a kick because I'm starting to think the spark is too weak, given that the original ignition system had external coils?!

Cheers