73 18hp fastwin problems

[Zimmpz]

Howdy Folks. Im the proud new owner of a 14 foot Starcraft with an 18hp Evinrude Fastwin (1973) and new to the forum. Ive been doing a lot of reading on here and been getting lots of great ideas on how to fix up my boat and motor. I figure its my turn to post and ask a few questions. First off I took the motor out when I first got it and it ran like trash. All the poping and sneezing you can imagine, then a violent shutter and it wouldnt start. Got home and found the flywheel key broke. Ordered a new one and while I waited...
1,Cleaned and re-built the carb
2,Cheked compression 1 Cyl 124psi 2 Cyl 122psi
3,Took head off, pistons and cyl walls look good
4,Cleaned and set points
5,took intake manifold apart and leafs and all look good.
6,took fuel filter apart and no holes in diaphram
7, took lower unit off unplugged all the blocked holes and replaced gear oil

So I got the key replaced it and hooked the motor up to the garden hose and it roared to life ran much better then before. Though not perfect. 1 of the coils looks old and I can see a slightly weaker spark. So here is the bad part I took it out to the lake and it wouldnt start. No spark. Took it home and the flywheel key was broken AGAIN!!!!!!!! So I guess my question is what could be going wrong to make the key break? The flywheel was tight. Does it need to be gorilla torqued? And second will that old coil with the slightly weaker spark make a dramatic diffrence in the preformance of the motor? I plan on replacing it anyways but just wondering. Thanks for any help

 

[restornator]

Re: 73 18hp fastwin problems

it should be torqued to 40-50 pounds. my guess is it wasn't. crankshaft must be completely dry or the flywheel will slip. you also need to look at the flywheel and see if the key slot isn't worn out.

also not sure how you hooked it up to a garden hose, because it's impossible

 

[Zimmpz]

Re: 73 18hp fastwin problems

I used some electronic cleaner around it maybe that left somthing on the crankshaft??? ill clean it up before I put a new one on. Key slot is fine. It was tightened as hard as I could by hand before I could no longer hold on to the flywheel. im assuming that is maybe slightly above 40 or 50 lbs. And as for the garden hose I had the muffs on the end.

 

[F_R]

Re: 73 18hp fastwin problems

The basics:
1. The shaft and taper MUST be clean and dry.
2. You MUST use a torque wrench to tighten the nut to 40-45 ft/lbs. Guessing just doesn't get it.

Ignore the above and it will shear the key. When it sears the key, it damages the shaft and flywheel keyways and maybe the tapers. Do it again and it will cause more damage. Do it again....well you get the picture. Eventually, it will be impossible to hold a key. Many motors have been consigned to the scrap heap because of this very problem.

Muffs won't work on that motor. Get it in the water. A large garbage can will work. But get it in deep enough.

Bad coils are a waste of time.

 

[14ftgrumman]

Re: 73 18hp fastwin problems

Do not run that motor on muffs, it won't work. Submerge the lu in a barrel, at least 1/2 way up.

And, there is vertually no way ou can hold the flywheel with one hand and tighten down the flywheel nut with the other and have any way near the correct torque spec.

Use a TORQUE WRENCH.

 

[Zimmpz]

Re: 73 18hp fastwin problems

Ok went to the dealer and ordered a new key and a coil. Told them my story and he said scuff the inside of the flywheel and the crankshaft for more friction and make sure it is torqued. Thanks for the replys ill give you all an update when the parts come in.