Timing

oGaryo

oGaryo

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Sorry for the recent rush of questions /forums/images/graemlins/blush.gif.. just had a crack at sorting out the timing on my 3.0l Mercuiser inboard and was surprised to see the timing mark advanced to about 20 degree btdc with the engine running at it's smoothest idle... attempting to get it back to 1 degree btdc wasn't possible before the distributor body hit the fuel pipeline from the fuel pump, the best I could get was itro 14 degrees btdc at the dizzy's furthest rotation clockwise..

I used a gunson timing light on lead #1, shorted out the two white connectors coming from the dizzy and disconnected the shift interupter... I did this after reading some googled text.. some advice also suggested grounding a single lead in the wiring harness?

I suspect I am doing something completely wrong and haven't disabled the timing advance so am not getting base timing readings.. also, the rev counter is still up the duff so I am not sure what idle revs I am getting but I'm pretty sure it'll be faster than required.

Can someone in the know give me step by step instructions for setting base timing please making it very very obvious what connections I need to make and/or break... if there's a link to pretty pictures showing what to do, that'd be even better.

In the meantime, I'm going to fix the rev counter.

many thanks, Gary
 
Hi Gary
I've never successfully used a timing light in my life...
my dad's method was simple-at a fast-ish tickover, advance the timing until the engine started to get uncomfortable, then back off until it ran smoothly. That was the system I employed on my Merc 3.0l (and every car I ever tinkered with)and it ran fine-I wouldn't get too stressed about it! If you hear 'pinking' under load (which I doubt you will) just back it off a tadge more...
 
realslimshady is right when it comes to any petrol engine with a dizzy it is best to do it by ear and try as 9 times out of 10 if an engine thats worn is set to the factory settings it wont run as smooth.
 
cheers guys, that's encouraging to know... I've received a pm with the exacting procedure and I'm doing part of it wrong, need to connect the leads going back in to the wiring loom after disconnecting the shift interupter switch.

The engine seems to run fine at idle and higher revs when not under load so I'm trying to find somewhere around here where I can take the boat for a test run after servicing the leg and before travelling too many miles with the boat on the trailer.. I'm not having much luck /forums/images/graemlins/frown.gif.. I feel another 'please help' post coming on /forums/images/graemlins/grin.gif looking forward to the day when I become knowledgeable enough to return the advice I'm getting /forums/images/graemlins/ooo.gif
 
Timing by ear....keep it coming.

We see loads of boats "timed by ear" i have been doing this 20 years i cant time by ear. You can be up to 10 degrees out.

The 3.0 litre if timed 6 degrees out blows the head gasket speak to any merc dealer big service recall a few years back from GM.

If you can time by ear you have a permanent job with me psml!!!!! /forums/images/graemlins/laugh.gif
 
dependin on the age of the merc and ignition system employed the merc 3.0 ran at 1 degree bdtc or 1 degree atdc or the later ones 2 degree atdc.

the earlier ones as in 1993-1998 if run 2 degree bdtc would blow the head gasket between 2 and 3 pots.

as for running under load under you hear it pinking then back off a bit is ludicrous!!! When you have backed off to a smooth idle your timing could be 6-10 degree btdc!

there is a special way to time these up and its not just with a strobe and moving the dizzy!
 
Gingie is right, you have to put the modern Mercruisers into 'service mode' before even attempting to adjust the timing or the system will just over ride and try to compensate which indeed can blow head gaskets, I've seen several gone between 2-3 cylinders.
You need to follow the instructions to lock out the module advance while you set basic advance then when you disconnect and reconnect the various wires it locks onto the new setting and holds it.
 
thank you spannerman....i have pm the procedure to gary

hows the boating life over there?
 
[ QUOTE ]
dependin on the age of the merc and ignition system employed the merc 3.0 ran at 1 degree bdtc or 1 degree atdc or the later ones 2 degree atdc.

the earlier ones as in 1993-1998 if run 2 degree bdtc would blow the head gasket between 2 and 3 pots.

as for running under load under you hear it pinking then back off a bit is ludicrous!!! When you have backed off to a smooth idle your timing could be 6-10 degree btdc!

there is a special way to time these up and its not just with a strobe and moving the dizzy!

[/ QUOTE ]
sorry, mine was a 1990 and didn't have any 'modules',static setting was 8 degrees btdc I recall...and ran fine like that
doesn't sound like you ever had to do this on the side of the road, gingie!
 
If you have the 3.0l with delco EST distributor:

1. Pull the leads off the ignition interuptor switch and connect them together.

2. Start the engine.

3. Connect the two white leads that hang off the distributor together with a shunt wire.

Base timing should be now set at 1 degree BTDC, if not then set it till it is, using a strobe light.

Once set, disconnect/reconnect everything, set the RPMS at 2500 and check you have 12 degrees advance.

You done.
 
well yours would of had the module in the distributor and would of needing to of been stuck in the "base timing mode" to correctly set timing.

I have been a mercruiser dealer for 20 years so i should know a thing or 2 about timing.

As for stuck on the side of the road what a you implying with you comment?

I have not attacked you or questioned your ethics! These forums are for points of view and assistance and stories. I have purley notified the facts on this users engine.

There was another type of ignition system on the 3.0L of your old engine which was a 3.0L DDIS which was completely digital.

The 3.0 litre even in the late 80`s was running the module!
 
This is the correct way to time up the 3.0 which me and Gary ran throught the other day.

The V6 and V8 merc non fuel injected need to be set in base timing.

There is a wire which a rubber blanking bung in just floating near the thermostat housing on the stbd side. This needs earthing and timing adjusted that way.
 
Looks like I have everything I need advice wise to get this job done properly (to spec).. thanks guys, invaluable again and as always, very much appreciated.

A big thanks to Gingie.. top drawer stuff mate both here and in the pm's you've sent me.. there's not many like you about these days. /forums/images/graemlins/cool.gif /forums/images/graemlins/cool.gif

Thanks also to everyone else who's taken the time to offer advice /forums/images/graemlins/cool.gif

going to give it another go..
 
calm down! if any attacking was done it was you on me...
what i was implying(!) was that when you're stuck on the side of the road because your Ducati 250* has shaken its points loose, pulling a timing light out of your back pocket isn't an option...
*-insert any appropriate vehicle/circumstance (BSA 650,Vauxhall Viva,Yamaha DT125 ,Suzuki GT550 etc etc...)
 
sorted (ish) /forums/images/graemlins/cool.gif

I had the carb running far too rich and the idle speed far to high as a result of the timing being out, the carb was compensating and the engine would stall if the mixture wasn't set as such. also, I made the assumption that the plugs don't need to be regapped off the shelf, have now set them to 0.035... finally, I've tweaked the choke setting (centralised it as a guess but will check what it should be later)

I can now get 1 degree btdc with base timing set, however the timing advances to about 14 degrees btdc when everything is put back!!!!..

The engine's definitely running sweeter after all that but there's clearly a bit of tweaking to be done once I get the rev counter working so I know I'm checking the timing at the correct revs.

I've take a couple of vids of the engine idling after the above was carried out and will post them up if it's possible to do so to gauge your opinion as to whether you think it's idling too fast.

The good lady wife is starting to accuse me that I'm doing all this for my indulgent self (gasp /forums/images/graemlins/shocked.gif) instead of preparing the boat for a safe outing.... I'd best not do anymore today /forums/images/graemlins/grin.gif

n.b. The engine wouldn't start with only the switch bypassed but would when coupled with joining the leads on the dizzy.

cheers Gary
 
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