Timing Question

[BackWoodsTracker]

1980 Mercruiser 228. OK, we had a great day on the lake. It shifted just fine without killing, choke worked great, boat ran well. I never messed with the timing as it seems to run just fine. I put the light on it, and it's sitting at about 14* at 800 rpm. The manual says to plug the vacuum advance and set at 8*, but there isn't a vacuum advance that I see. I even had a mechanic come look for one, it's not there. I know too much advance isn't a good thing, should I leave it as is, or set it back to 8*? Or, is there anybody that knows what the advance should be at say 2,000 - 2,500 rpm? I could set it to that and be happy. By the way, in the driveway it seems to run just as good, if not a little better at 8*.

PS, thanks for all the help to get me this far, my dad is now very happy with the boat.

 

[Fishermark]

Re: Timing Question

The manual says to plug the vacuum advance and set at 8*,

What manual is that? As you note, boats don't have a vacuum advance.

Go to the top of the page and you can download the OEM manual for your engine.

 

[BackWoodsTracker]

Re: Timing Question

I can't seem to open the manual in the adult section. The one I have is Clymer.

 

[Fishermark]

Re: Timing Question

It may be a big file - save the file on your hard drive and then open it.

 

[BackWoodsTracker]

Re: Timing Question

I can't open the file. My computer can't find a program to open it, and I'm not all that savy to figure it out.

 

[ziggy]

Re: Timing Question

mercruiser will sell ya the book. $100 round abouts from what i've seen. + there's always ebay. i never buy anything there. but i did get a couple of used service manuals from them....

 

[Don S]

Re: Timing Question

Which link are you looking at? Best to use this link for that #3 manual.
Go to the adults only sticky, and the service manual links.
Find this and follow it. The download is smaller, and the read me file explains what to do.

 

["G"]

Re: Timing Question

I can't tell you how many folks are tricked by timing. The first thing that needs to happen is to take the throttle cable from your control box off the carb. Next; adjust the idle screw so that you are idling (at as low an RPM as it will run). You should be under 650 RPM or your weights are swinging fast enough to advance the timing.

IT IS CRITICAL that you do not have any opening at all on your carb throttle plate when adjusting the timing. Once you are running at 600 or if possible below that adjust the timing. Remember that as you adjust and the engine revs up you will need to readjust/decelerate to 600 RPMs.

After you get your timing set, bring the engine idle up to 650 when in gear. Turn the barrel nut on your throttle cable to fit the throttle barrel post on the engine after attached to the carb.

In short it is impossible to set ignition timing when your engine does not idle correctly. The springs on the weights located in the bottom of your distributor do not (should not) allow advance until your RPM exceeds 650 or so. If the engine idle is above that... well you get the picture.

 

[Don S]

Re: Timing Question

IT IS CRITICAL that you do not have any opening at all on your carb throttle plate when adjusting the timing.

That has nothing to do with setting the timing to specs. The idle rpm in the manual is 650 to 700 rpm in gear. That is where they want the 8? BTDC at, not at 5 or 600 rpm. Then, when the engine is at a certain higher rpm, the timing reaches it's max. as shown in the advance curve chart below.

 

[BackWoodsTracker]

Re: Timing Question

Thanks again. I set my idle down to 650 and set the timing to 8*. I'll take the timing light with in the morning for the fishing trip. We'll see how it goes.

Also, I guess I'll read the read me file. I'm on it right after this post

 

["G"]

Re: Timing Question

That has nothing to do with setting the timing to specs. The idle rpm in the manual is 650 to 700 rpm in gear. That is where they want the 8? BTDC at, not at 5 or 600 rpm. Then, when the engine is at a certain higher rpm, the timing reaches it's max. as shown in the advance curve chart below.

The idea is not to set timing at a specific RPM but rather a slow enough idle so that the weights are not advancing the timing when you are setting the timing. If the engine runs at 550 RPM and you set timing there it most likely will not change when at 650 RPM in gear. See your chart...

It's called reassurance that the weights are not advancing the timing. Check it out... I think we're saying the same thing with technicalities. The post was if the throttle plate is open you will have a high idle.

 

[BackWoodsTracker]

Re: Timing Question

Well, the fishing trip went ok. The boat ran sweet under power. It ran good for the first 1 1/2 - 2 hours of trolling, then it started missing and it would die every once in a while. To me it sounded like it was loading up, running too rich. We gave up on fishing and decided to give it a run to clear out the plugs. The boat didn't want to run right then. It did get up on plane after playing with the throttle and easing into it. It wasn't firing on all cylinders all the time. It'd hit every so often, but never steady. I went back to idle and it wouldn't accelerate again. We limped back to the launch and got it home. The plugs all look ok to me. I put in new plugs just to do it, but I'm thinking it may also be a bad coil. This was the first time my dad and I had the boat out for any lengh of time, so I don't know if it has happened before. Could this happen with a coil that is on it's last legs? Or, where else should I look to be on the safe side?

 

[Don S]

Re: Timing Question

Sounds like a fuel delivery issue. Did you check your fuel filter/water seperator for water? If no water, might try this. May be a plugged vent, pickup, antisiphon, or an air leak. The tests will tell you.

http://forums.iboats.com/showthread.php?t=283269

 

[BackWoodsTracker]

Re: Timing Question

Thanks Don, I'll look into that in the morning. On a side note, where do I put the vacuum gauge for setting the carb? I don't see any vacuum lines other than the choke pull off thingy. I was just setting it by ear, now I want to get a bit more accurate.

 

[gadget73]

Re: Timing Question

If your intake has a pipe plug threaded into it somewhere, remove it and install a nipple so you can hook up the vac gauge. Most boats have no vacuum provisions under normal circumstances, nothing uses it.

 

[BackWoodsTracker]

Re: Timing Question

That's cool, I have a plug in the intake. Now, can I use the compound gauge mentioned in the "Fuel system test" for the carb, or will I be buying 2 gauges?

 

[Don S]

Re: Timing Question

You might consider starting a new thread with a title that askes your newest question. DOn't forget people still think this is a thread aabout a timing problem.

 

[JustJason]

Re: Timing Question

same gauge.