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

[sojo81007]

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

Boy am I glad that I tapped that hole crooked! Pulled the head today and there were several shavings inside the hole...would have been bad news for sure.

The pistons look pretty good, some carbon but not too bad. The cylinders have markings on them, I'm not sure what a "scored" wall looks like but should it have markings? Swirls/patterns, etc? Since it had 119/118 for compression I'm assuming all is well.

As for the head, it looks to be in good shape. I called a local garage and asked them about it, and they referred me to a local welding/machine shop saying that they will weld the hole shut and re-tap it. Is that a viable option, assuming that it's cost effective?
Any negatives to it?

 

[Ross72]

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

Sojo where are you located? I have a dozen or so big twins in various stages of disrepair in the shop. Shoot me a pm if can't find one local.

 

[sojo81007]

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

Sojo where are you located? I have a dozen or so big twins in various stages of disrepair in the shop. Shoot me a pm if can't find one local.

I have several people who've contacted me through the antique outboard site. One guy is checking to see but he's pretty sure he has one and at a very reasonable price. I'm in huntingdon pa (16652). Even if I get a head I'm interested in a parts motor - I've committed to this thing...or a kayak, haha

 

[kfa4303]

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

+1 a parts motor is ideal, if you can find one. Thankfully, many OMC parts are interchangeable between models of different hp and year.

 

[sojo81007]

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

Thanks for all you help! The people at the antique club have been great as well. I've had several offers ranging from $20-$65 so I should get one ordered pretty soon. I have some random parts from a 50hp that I was just going to scrap, but now I know that I need to keep them to help somebody else. I've made a parts shelf so I know what I have. These parts aren't going to get any easier to find.

 

[Ross72]

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

Glad you found what you needed.

 

[Ross72]

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

I'm in Corning NY about 3 hours from you. If you decide that you want or need a parts motor let me know and good luck getting her going. The old big twins are one of my favorites. I'm redoing a 1957 35 hp big twin longshaft now. Its a tiller recoil start.

 

[sojo81007]

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

Finally got a new head ordered, it should be here any day. Any thoughts/advice on making sure the head was flat and also what I should use to clean any old gasket material/carbon on the pistons?

i had planned on using some type of sealant on the gasket but it said "do not use sealer" so I will not use any.