Evinrude 18hp questions.

[steviecops]

Hi<br />I've just got a 1966 Evinrude 18hp, longshaft, that needs some work doing to it. Could anyone tell me what the correct fuel mix is? <br /><br />Also, could anyone tell me how much this engine weighs? It feels as light as, or lighter, than my longshaft 1986 Johnson 9.9, which according to the manual weighs 77 lb.<br /><br />If the fuel is 50:1, and it doesn't weigh more than my 9.9, I'd like to use it as the auxillary motor on my 17 ft tri-hull fishing boat. What sort of performance could I expect compared to the 9.9?<br /><br />Sorry for all the questions , any advice would be appreciated.<br /><br />Thanks<br />Steve

 

[fireman57]

Re: Evinrude 18hp questions.

Mixture is 50;1. This engine will have quite a bit more power than your 9.9. You will be surprised by the performance and fuel comsumption. If you just got it do yourself a favor and replace the water pump impeller and clean the carbs good.

 

[G DANE]

Re: Evinrude 18hp questions.

If its manually started, it weighs just below 85. They were good, quiet motors, smooth running. I dont think they were hard on fuel.

 

[steviecops]

Re: Evinrude 18hp questions.

Thanks fireman57, <br />that's good news about the fuel mix. I didn't want to have to take two fuel tanks out fishing. I plan to do a thorough job on the engine so I'll do the whole water pump and rebuild the carb with an OMC kit. I'm going to replace the coils, HT leads and head gasket too.<br /><br />G DANE, 7 or 8 lbs is about the same as a good Bass, so I think my boat will take the extra weight ;o). I think it'll be worth it if there is that much difference in performance.<br /><br />Thanks.<br />Steve

 

[Solittle]

Re: Evinrude 18hp questions.

Might also replace the thermostat & gear oil (new fill/drain plug gaskets of course).

 

[fireman57]

Re: Evinrude 18hp questions.

I didn't mean to say that it would just drink your gas tank dry but it will use considerably more than your 9.9. Like G Dane said they are a good engine.

 

[steviecops]

Re: Evinrude 18hp questions.

I'm glad to hear how good they were/are. As long as it doesn't drink more than my 55 main engine, I'll be happy ;0). I'll change the thermostat and gear oil also.<br /><br />Thanks<br />Steve

 

[steviecops]

Re: Evinrude 18hp questions.

Hi<br />One of the jobs I need to do is sort out a stripped thread in one of the spark plug holes. Can anyone tell me what thread size helicoil I need?<br /><br />Thanks<br />Steve

 

[Paul Moir]

Re: Evinrude 18hp questions.

Metric 14mm (x 1.25mm) thread 3/8" (1 cm) long. I like to coat the outside in hi-temp red loctite, but it's probably uneccessary for heli-coils. Nice thing about that brand is they're stainless.<br />I strongly suggest you pull the head to do it.

 

[steviecops]

Re: Evinrude 18hp questions.

Hi Paul<br />Yes, the head is off already. I've actually got a johnson head that I was going to replace it with, but I'm just thinking that it'd be nice to keep the original head on it so it doesn't look odd! The Johnson head is a dark greeny brown colour.<br /><br />Thanks for the info.<br /><br />Steve

 

[BugEyes]

Re: Evinrude 18hp questions.

If the Johnson head fits, use it. Repaint it to match if that's an issue.

 

[Paul Moir]

Re: Evinrude 18hp questions.

I'm inclined to disagree with you on that point, PikeFisher. Since the helicoiled threads are stronger than the originals, I think that installing them improves the outboard. It seems to me that most OMC heads I've seen from that era have at least one heli-coil installed.<br />It would certainly be the simpler solution though.

 

[BugEyes]

Re: Evinrude 18hp questions.

I agree that a helicoiled head would be stornger. But if the tread is good in the Johnson head I would still use it. These heads does not get too easily stripped if the plugs are not overtorqued.<br />I have an early 70's 18 hp and a 1980 25, none of them have had the treads stripped in the plugholes.

 

[G DANE]

Re: Evinrude 18hp questions.

Up to 1975 they had the short threaded spark plug holes, and lots of them had stripped threads in the one hole. The bushings tend to stick to the spark plug instead og head, not a good thing. I would recommend the helicoil, better than original threads.

 

[steviecops]

Re: Evinrude 18hp questions.

I've noticed that there is a slight diference between the original Evinrude and the Johnson head. Both have a kind of ridge around the plug hole on the inside of the head, but on the Johnson head it's slighly longer. Could this be what G DANE is talking about with the later heads? Would the piston come into contact with this longer ridge?<br /><br />I've just priced a helicoil kit and it comes out at around £70! That's about $130! So if the Johnson head is the newer type and less lkely to get stripped, and that longer ridge inside the head won't affect anything, I think I'm going to use the Johnson head.<br /><br />Thanks<br />Steve

 

[G DANE]

Re: Evinrude 18hp questions.

I might have a evinrude head for the 20 HP in my shop somewhere. Is had insert in the one hole. I can try to look for it if you are interested, its free if I still have it, just pay for shipping, only its a couple of years ago i last saw it. Not that far from DK to UK.

 

[G DANE]

Re: Evinrude 18hp questions.

Oups double post !!!

 

[steviecops]

Re: Evinrude 18hp questions.

Thanks G DANE, that's very kind.<br /><br />Let me know if you find it. steviecops@aol.com<br />If not, I still have a few options. Either use the Johnson head, (would the johnson head I have fit with the longer plug holes?), or take the Evinrude head to a shop to get a helicoil fitted so that I don't have to buy the whole kit.<br /><br />Thanks again.<br />Steve

 

[itstippy]

Re: Evinrude 18hp questions.

$130.00 for a helicoil kit!?! That can't be right. Won't a $15 special from the car parts store (NAPA, Checker, Bumper-to-Bumper, ...)work?

 

[steviecops]

Re: Evinrude 18hp questions.

We're talking rip off Britain here itstippy!<br /><br />The kit, which includes tap, insert tool and about 12 inserts costs around £70. If I knew somewhere over here that did them at a reasonable price I'd buy the kit, but I can't see how it warrants that sort of money. I only paid £30 for the engine!