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Old 01 September 2009, 09:28   #1
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Mercury clamshell iginition/timing

Seen as the useless gits who were meant to fix my engine couldn't be @rsed its back to the drawing board.

Just spoke to a lad who said the timing or iginition (can't remember which) may need advancing or retarding?

How do I do this?

Its a Mercury clamshell mid eighties 60hp.
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Old 01 September 2009, 18:27   #2
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What you want to do is a link and sync. If you don't have a Merc manual than you need to go to the US, iboats.com website and look on the merc OB section for link and sync.

It's advancing the ignition along with opening the throttle, Not rocket science but you need to do it right.

Hope thats what you need.

I have a late 80s Merc 60hp, its a great engine, reliable so far but it does smoke as it runs on 50:1. I took off the autolube and now pre mix.

Cherers Davej
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Old 02 September 2009, 01:37   #3
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It might as well be rocket science as I haven't a clue about stuff like that.
I had a look on iboats but couldn't see anything?
Mines premix and does smoke a little.
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Old 02 September 2009, 04:00   #4
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I think all premix 50:1s smoke! It's part of the charm.......

Setting up the timing isn't too difficult - Clymer covers it in about half a page column. If you get no luck finding anything let me know & I'll copy the 4 or 5 paragraphs for you.

One question tho' - did he tell you why he thought it needed moved? Unless someone has fiddled with it or taken the crank out it shouldn't need adjusted. Those machines are quite sensitive to it and I believe the original factory setting although giving shedloads of grunt resulted in a high chance of the early demise of the pistons due to pre-ignition, and so I believe the optimal setting for WOT is 19deg BTDC as opposed to the original twenty something.

What was wrong wth it in the first place?
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Old 02 September 2009, 05:38   #5
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It runs at tickover and in gear but once to 50% throttle in gear it cuts out. It restarts fine and revs freely in neutral.
It did for half an hour run through half throttle to WOT but after that it was back to normal.
The lad hasn't seen it but said he's had the problem before on that engine. Another mechanic has replaced a control unit or something just under the flywheel which my brother tells me is something to do with timing?

Wheres the best place for the Clymer manuals? Is it this one I need?

http://marinestore.co.uk/Merchant2/m...manuals-clymer

Thanks
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Old 02 September 2009, 07:23   #6
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Yeah, that should cover it.

When it cuts out is it with a "bang" (I use that term metaphorically) or just "fades out"?

That may be as simple as cleaning the main jet! No load High RPM doesn't need anything like mas much fuel as it doing proper work, so will likely revs itself to bits in neutral. It's a PITA to get the carbs out (you have to take off the entire front end of the engine) but if you can dis / reassemble things, probably worth trying that. You;ll find the exploded diagrams on Ishop Marine.

The thing under the flywheel is basically a set of coils to generate the ignition sparks. (the flywheel has a load of magnets round it;s rimm that generates the electricity) The "adjustment" there is it's position relative to the rest of the engine so the sparks happen a few milliseconds earlier at high RPM (move the trhottle lever on the side, it's basically the thing that moves on the sprung outer lever)

Mine was a bit lumpy when I got it. Turns out it was a combination of a duff HT lead and some solidified grease. assuming we have the same engine -

Things to do:

1) Visually check your HT leads for corrosion on the end plugs and that they haven't been damaged on that convoluted unsupported route to the plugs. If you have a "proper" auto factor nearby you should be able to replace them for around 15. Probably worth replacing the plugs too.

2) On the throttle lever assembly (port side) check to see if the two arms move independently. If you whack the thottle open the lever on the outside should follow with a visible delay (to allow for the finite time the engine takes to speed up - it delays the advancing of the spark by a second or so). If the whole lot moves as one, carefully undo the big bolt it all hinges round. Clean out the solidified grease in the spring housing, re - lube & reassemble. (you'll need to disconnect the rods at the top to get it back together)

3) Open the carbs & see how much gunk is in there.

Unless someione has been fiddling, the timing usually doesn't need adjusted.
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Old 02 September 2009, 09:15   #7
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Blasted carb cleaner through from the fuel bowl and a bit of shite came through. Its had new control cables and everything appears ok, I greased it all when I put it back together.

Will have a look when I get home... you don't fancy fixing it do you!
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Old 02 September 2009, 09:50   #8
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Blasted in through the drain hole below the air intake? If you got crud out of there, I bet there's more sh!te been wedged in the jet(s)..... what grease did you use on that spring mechanism on the throttle levers?

Check the leads & that mechanism on the throttle. Taking the carbs out is actually easier if you loose the whole of the front of the engine - If you find nothing wrong with the leads let me know I'll try to describe how I did it second time round - first time I removed the carbs I left the air box in place. A few unrepeatable words were muttered that night........


Thanks for the offer, but I've got one of my own to rebuild at the moment.......
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Old 02 September 2009, 09:53   #9
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Forgot to say it just dies no loud bang or anything spectacular.

I looked at taking the carbs off but if I do that engine will never run again, too many small fiddly bits for me.

The carb cleaner should have come out of the main jet should it if it was squirted through the fuel line?
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Old 02 September 2009, 10:40   #10
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If it just kind of "fades out" it's likely fuel (or lack of it) causing the problem. Electrical things tend to either work or not, and very rarely "fade" when they die (apart form new high tec ones where if a sensor goes, the engine management may "fade" the power down to limp mode).

Aye, they're not the easiest to take apart. The reason they're so light is that the carbs are part of the structural stuff holding the front on! - there's no wasteful bracketry on these lumps!

If you squirted it through the fuel line, I would have expected nothing to come out after a lot of squirting - Quick explanation - Carbs basically use air pressure (or vacuum) to sook the fuel through the small jets. The fuel in the bowl below needs to be kept at a reasoanbly constant level so that the vaccuum is properly balanced with the weight (quantity) of the fuel being sucked up the pipe (a.k.a the jet). Inside the fuel bowl is a float that basically works a valve a bit like the float in your toilet cistern. If that is set up properly then you should be able to pump fuel in until the bowl fills, then the primer should go hard as the float closes the valve, so holding the bowl at a constant level.

- Did the primer bulb go properly hard when you primed it?

Thing is unless you have an entire bowl full of cleaner for the float to float on, the vave won't shut, so you may get some cleaner coming up through the jet. Idle ports are miniscule, and usually block first, but if your lump of crud has got in the vicinity of the main jet when it's at open throttle it would be like rolling a ping pong ball in front of a Dyson hose.

Have you taken the front lid off the air box? If you don't want to take the carbs off, can you get the cleaner to take a WD40 straw? 8 (I think - may be more) screws hold the air box cover on. If you can get that off, you'll see two big nuts below the two air ducts of the carbs - they are the drain for the carb bowls. Undo them & see what drops out. May be worth flushing through again with them open. Once you've done that use the WD40 straw to "reverse flush" the main jets (That might need a bit of "keyhole surgery"- your carbs may have a venturi round the top of the jet) but if you can reverse flush the jet, you may find more crud drops out the drain hole. Might also be worth once thedrain screws are out, blasting the bowl from that angle?
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