Link and sync

[quazerboy]

Hi Guys<br />I've got an old 'rude 18hp I don't know the year but the serial no on the clamp is: 18202rc78793. my real question is:<br />together with my father we have rescued this motor from the scrapheap, it's got a fresh coat of paint and looks superb however it dosent go all that well. I received the motor last year and don't know how long it had been stood before then, but it was a complete cow to start, and didn't idol too well, we put it on the boat and gave it a good thrashing to see if it would clear up a bit but no different, this year we have checked the points gap, replaced the plugs (big fat blue spark) and rebuilt the carb and although it started 3rd pull it seems to be running about the same as last year, refusing to tick over well and using loads of fuel ($7 a gallon over here in "good" old blighty!<br />The only way I can get a manual is from the states, and I'm on holiday in a couple of weeks with the boat.<br />How do I do a link and sync? I think that might be the problem, also the engine seems to tick over best with the mixture screw only about an eighth of a turn out, however after a few seconds the engine coughs and sometimes this is enough to stall it. I've noticed some marks on the throttle cam are these something to do with the setup? I realise there are a lot of questions here, and know that the best thing to do would be to get a manual, but I really would like the engine to be running reasonably well for my holiday,and would appreciate any advice.<br /><br />Thanks in advance<br /><br />Lee

 

[CATransplant]

Re: Link and sync

Model 18302 is a 1963 18hp Evinrude. I can't find an 18202, but I'll wager it's a 1962 or 1962.<br /><br />1/8 turn out on the mixture screw is very little. You don't say if this is the idle mixture or high speed mixture. I'll assume it's the idle mixture, although what I'm about to suggest would affect both.<br /><br />This would seem to me to indicate that you may have your float level set wrong, or that the float is saturated with fuel and not floating properly.<br /><br />That would cause an over-rich mixture and poor running, along with high fuel usage. You have good spark, apparently (on both cylinders?), so this rich mixture may be the whole problem. <br /><br />I'd pull the float bowl on the carb and have a look. Check the float. It is probably the original cork one. If it feels too heavy, then it's probably fuel-soaked. If you can get the new plastic replacement, so much the better, but you can also rescue the cork one. Dry it out well. I just put mine in the sun for a couple of days, but you can also use a hair dryer to add additional heat. <br /><br />Coat the dried float liberally with shellac. Several coats.<br /><br />Then replace it and adjust it so it is level with the carburetor body. Replace the bowl and re-install the carb. Test the running now. You will no doubt have to re-adjust the needles again.<br /><br />Let us know how this works out. I'd certainly do this before bothering with anything else.

 

[Paul Moir]

Re: Link and sync

That's a '72 you've got there.<br />Link and sync is pretty simple - the little roller that follows the cam should be just between those two marks when the throttle butterfly on the carb *just* begins to move. You can amplify the movement of the throttle butterfly by attaching a piece of wire to the throttle shaft. A precise adjustment is important.<br />To adjust the timing, loosen the clamp on the linkage between the throttle shaft and the roller follower (it's pretty obvious how it works).<br /><br />That said, usually a bad link&sync affects the midrange more. If it's using tonnes of gas, look for things that could cause it to run rich. Suspects are float adjustment (should be set level with the casting rim of the carb body when held upside-down), idle adjustment, or possibly a leaking fuel pump. The fuel pump is easy enough to test - simply unbolt it from the block so it hangs free and pump the primer bulb hard. If fuel comes out the little hole on the back, then it's got a hole in it's diaphram causing whichever cylinder it's attached to to run rich.<br /><br />Tell us what you find!<br /><br />PS - search ebay for "(Johnson, Evinrude) (25, 25hp) manual" and you'll find a couple '72 25hp factory manuals. If the seller only ships to the US, I find simply emailing them will get you permission to bid.<br /><br />EDIT: Pardon the post collision, CATransplant!

 

[CATransplant]

Re: Link and sync

OOPS! I re-checked. That's a 1972 18 hp. I didn't follow down long enough in the list.

 

[CATransplant]

Re: Link and sync

Paul,<br /><br />Now we're posting at exactly the same time. I'm sure I must shift to another set of hours here. [grin].<br /><br />BTW, would you take a look at my idea on that welded shift rod problem. I'm trying to work out a new solution for this problem that is all too common to the twins. I think I may have something that might save a ton of work for some folks.

 

[quazerboy]

Re: Link and sync

Gentlemen, you chaps are fantastic! that gives me plenty to chew on. I'll report back when I've done what you suggest. In reply, yes the spark is good on both cylinders, and when we had the flywheel off the stator plate and points looked brand new, which is what made me suspect a setup issue, as I said I really don't know anything of the history of this engine and it may be that it was never set up propery after the ignition parts were replaced, but that was just clutching at straws. the carb will be stripped tomorrow!<br /><br />Please could you clarify the age, is it '62 or '72, gut feelings tell me 72.<br /><br />thanks once again.<br /><br />Lee

 

[CATransplant]

Re: Link and sync

It's definitely a 1972 model. While the 1963 WAS, indeed 18302, OMC, in its infinite wisdom, did not number models sequentially. In 1972, the model was 18202, as on yours. <br /><br />That will teach me to use my browser's search tool, rather than simply scrolling down the model number list. Silly CATransplant!

 

[RPJS]

Re: Link and sync

Hi Lee<br /><br />Your motor is a 1972.<br />When you rebuilt the carb did you soak it in cleaner and blow out with compressed air, it sounds like you may have some crud in there.<br /><br />Link & Sync,<br /><br />Center the cam follower roller between the throttle cam marks. Loosen the throttle shaft arm screw. Hold the cam follower tightly against the cam and tighten the throttle shaft arm screw. The throttle valve should start to open as the edge of the cam follower roller passes the second cam mark.<br /><br />If you arn't 100% sure about crud in the carb I would strip it down again and clean B4 doing link & sync.<br /><br />Richard<br /><br />Edit: I must learn to type faster,

 

[quazerboy]

Re: Link and sync

Sorry to be a pain gents, but just how much fuel would you expect this motor to burn at WOT?<br /><br />Lee

 

[MGuckin]

Re: Link and sync

Rule of thumb is approximately 10% of your horsepower in GPH.

 

[Paul Moir]

Re: Link and sync

Or 0.4 litres per hp per hour. Seeing Lee is from the UK there might be some confusion between Imperial and US gallons. So at full throttle (18hp) you can expect to use somewhere around 7l each hour.

 

[tritak]

Re: Link and sync

I also have a question about the Link-N-Sync. I have a 1976 Johnson 70 that I just rebuilt the carbs and my manual doesn't go into great depth about how to link-n-sync. Does the cam roller need to touch the cam before it starts to move or should there be a gap in between them? thanks for any help!

 

[Paul Moir]

Re: Link and sync

Welcome to Iboats, tritak!<br />I have absolutely no idea. But I'll bet there's lots here who do. Proper form around here is to start your own post rather than try to find one that's similar. There's just way too many posts here for that to work. Title it something like ''76 70hp link-n-sync clarification' and you'll get responses from people who do know.

 

[quazerboy]

Re: Link and sync

Well I've managed to get hold of a carb repair kit for a not unreasonable (for the uk) $35, I've not actually picked up the kit from the chandlers as yet but along with the float and various gaskets it comes with core plugs and lead shot. Is it worth me stripping the carb and replacing these parts? I understand that I will be able to clean out the various orifices having removed these plugs is it a tricky job to reinstall the shot and plugs. I have a mechanical aptitude but I've never done this before.<br />Thanks<br /><br />Lee

 

[fireman57]

Re: Link and sync

Easy to do. Get a good manual. Worth the price of one repair.

 

[tritak]

Re: Link and sync

Thanks for the advise Paul, I'll keep that in mind!

 

[Paul Moir]

Re: Link and sync

Lee, there's a couple ways to remove them by punching through them with a hammer and spike, or by drilling them and inserting a small screwdriver or pin and peeling them out. Installing them is much easier than removing and part of a complete carb rebuild. The instructions are left out of the Seloc manual, and I think the Clymers too so I wrote this up about them:<br /><br />Disassembling:<br />Your new carb kit ought to come with replacement, slightly convex core plugs. Before proceeding, make sure they're they are the same size as as the ones you are about to remove. If all is well, drill a 1/8" hole in the centre of each core plug. Then insert a small screwdriver or nail through the hole, and pry the plug out. It is very important that while drilling and prying, you do not let anything damage the surfaces underneath the plug. So restrict the drill bit from piercing much more than 1/16" beyond the core plug.<br /><br />Assembling:<br />Coat the outside edge of the core plug with a slight amount of fuel proof gasket sealer. (Although this step isn't strictly necessary, I find it helps seal the plug and saves problems down the road.) Now place the plug convex side up atop the boss where the plug rests. Then, using a small drift and hammer, tap the top of the core plug so it expands until it jams tightly against the core plug's socket. Give it one extra tap for good measure.

 

[quazerboy]

Re: Link and sync

Thanks Paul, manuals are difficult to come by in the UK, however I've just found somebody selling CD versions on Ebay, so I'll give that a go. Meanwhile at least I can be getting on with things at the weekend. I do have a 1975 Johnson 20hp and 25hp manual that somebody gave me, the motor looks pretty much identical to mine, so I've been following most of the way through that, but it's really nice to know there are such generous people in the world.<br /><br />Lee

 

[quazerboy]

Re: Link and sync

I picked up a carb repair kit and re installed the plastic float as directed here, blew out passages with air and carb cleaner and re assembled and she works, runs like a dream-ish, It is definitely much better than before, but with all the unburnt fuel in there it'll be hard to tell if we've managed to fully cure it until we've had it on the water and given it a good sound thrashing! Tickover is much lover than it was and the mixture screw is about 3/4 of a turn out for best running. It's still missing a little at tickover, but it's hard to tell what I have tickover set to because I dont have a tacho.<br />If I suddenly slam the throttle shut (only from the "start" position, it sometimes coughs and stalls quite hard, is this normal? Furthermore what should be the correct plugs for this motor, I'm currently running NGK's as champions are more difficult, though not impossible to get hold of. Would champions be better?<br />I am nearly there and couldn't have done it without you all, thanks again<br />Lee

 

[quazerboy]

Re: Link and sync

bump