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Eratic timing marks at idle with timing light. 1989 2.3 L

I have a Bayliner capri with an 89, 2.3 litre Ford OMC cobra. I just got it and i was checking everything over. I adjusted the points they were a little open but when i put a timing lignt on it I am having a hard time seeing the marks. The are very eratic. The engine doesn't seem to run too rough. Any common problems with this or ideas?

Thanks,

George
 
Re: Eratic timing marks at idle with timing light.

How did you set the points, using a feeler gauge or by dwell meter?
 
Re: Eratic timing marks at idle with timing light.

Might be a good idea to just tune it up with new plugs,wires,cap,and rotor. An erratic timing signal can be caused by a bad plug,or wire,etc. If the parts are original,or you have no idea of the last service,just change it out and be done with it. Same goes for the water pump impeller. After all... it is a 21-22 year old boat.
 
Re: Eratic timing marks at idle with timing light.

Or you might have a distributor on its way seizing up.
Unfortunately been a problem with those engines.
Pull out the dist and check, you may be able to save it before something more expensive breaks!
 
Re: Eratic timing marks at idle with timing light.

Yes, erratic display from the timing light is an indication that something is amiss.

Try taking the Timing Light take-off point from the pole at the Distributor, and if it is the same, then it isn't the Lead that is the problem.

Could be a Timing Chain that is on its' way out as well. Not up with your engine, as it could have simple Timing Gears, and if so, the teeth could be on the way.

Bruce.
 
Re: Eratic timing marks at idle with timing light.

I am assuming the 2.3L has the Mallory OEM distributor and has all the correct parts.

Make sure the rotor under the distributor cap is not all worn out and loose.

Make sure the distributor cap is seated and tight to the housing.

That distributor has a spring loaded mechanical advance. Make sure the distributor cam rotates while the distriutor drive shaft is stationary. This can be done by removing the distributor cap and exerting rotational force, by hand, on the rotor. The cam should rotate freely and spring back to position by itself. If it doesn't, it may have either a weak (stretched) or broken spring; or the distributor cam shaft/bushings may need cleaning and re-lubed with the proper grease.

Next, check the distributor shaft bushing wear by rotating the engine manually until the points are fully open. then push and pull on the distributor shaft (sideways or back and forth) and see if the points open up more or close. If there is a lot of play in the bushings, the timing will be erratic.

Of course, check to make sure the points are in good condition and installed properly.

If all is well so far, pull the distributor and check for gear teeth wear.

Check the timing belt for looseness.
 
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Re: Eratic timing marks at idle with timing light.

I'm no expert, but timing isn't usually performed at idle. Idle is always jumpy. Bump up the rpms and it may settle in and give you a more accurate display.
 
Re: Eratic timing marks at idle with timing light.

With my race engine, I always timed the engine at 3,000 RPM.

But, with basic run-of-the-mill engines, they are set at idle, but at what idle is specified in the Shop Manual.

Bruce.
 
Re: Eratic timing marks at idle with timing light.

The 4 cylinder distributor points cam will dedicate 90* to one cylinder. (360 divided by 4 = 90)
Of this "90", XX will be dwell......., YY will be open.
32* dwell does not sound correct for a 4 cylinder engine........ see OEM specs!

Secondly, point gap is an estimate ONLY of correct dwell..... always set dwell using a dwell meter.

Thirdly, a mechanical advancing system that is NOT holding BASE mode only at idle speeds, can cause an erratic RPM at low speeds/rpm. BASE should remain BASE until above idle RPM. Only then should we see any mechanical advancing occur!
(worn, broken or missing cam/weight springs can cause this)

Fourthly, a worn/wobbly distributor upper shaft area can cause an erratic dwell, of which can play some tricks on you.

Always set BASE, followed by checking to see if your total advance (aka TA) is working correctly, and by seeing if it is offering the correct spark lead at the correct RPM.
DO NOT arbitrarily pick or set a TA........ this MUST be correct for YOUR engine and at the OEM prescribed RPM.
Again, see OEM specs for this.

BASE is BASE, and is BASE all day long. We start and idle on BASE only!
Of the two, the progressive curve up to, and including TA, is much more important, IMO.
 
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Re: Eratic timing marks at idle with timing light.

At 600-650 RPM, the timing mark on my 2.3L is steady at 10 deg. BTDC. Using a higher RPM to set the timing will result in overall low timing and poor performance.

That is because the spring loaded centrifugal advance starts advancing the timing at some point above idle.

I do not have the distributor advance specs for the 2.3L, so I don't know exactly at what RPM it starts advancing. At 600-650 RPM, the advance weights are held in place by the springs. As the engine speed increases, the weights (by centrifugal force) overcome the spring tension and cause the ignition cam to advance the time the points open.

If the springs are worn out or one is broken, the timing will be all over the place at idle.
Also, if the distributor bushings are worn out, the ignition points gap will change and cause the timing mark to fluctuate around and the timing may end up being off throughout the RPM range.
 
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Re: Eratic timing marks at idle with timing light.

At 600-650 RPM, the timing mark on my 2.3L is steady at 10 deg. BTDC. Using a higher RPM to set the timing will result in overall low timing and poor performance.

That is because the spring loaded centrifugal advance starts advancing the timing at some point above idle.
......................................................
If the springs are worn out or one is broken, the timing will be all over the place at idle.
Also, if the distributor bushings are worn out, the ignition points gap will change and cause the timing mark to fluctuate around and the timing may end up being off throughout the RPM range.
David, couple of things if I may:

You've pretty much said what I had previously posted re; the worn distributor parts.... and that's OK, maybe you did not see my post.
However, regarding setting timing at higher RPM..... this is called TAT.... or Total Advance Timing.
This is much more important than BASE, and this is done often, or maybe better said, "should be"!
There is no real down side to doing so regarding BASE advance.
If setting TA throws BASE off, then out comes the distributor for rework regardless!
IMO that is.
 
Re: Eratic timing marks at idle with timing light.

Ricardo,
Please see my post #7.
No, did not see your last post before adding more info on the distributor.

I use to rebuild distributors as part of a fleet mechanic job. We used an ALLEN Distributor Tester to check the advance curve against the specs.
This is how we determined TA, was on the machine. Once the distributor was right, the BASE timing was set on the vehicle. We did this to 120 vehicles in the fleet.
 
Re: Eratic timing marks at idle with timing light.

David, my bad! I just went back and read your post #7.
I guess between the two of us, we have doubled up enough info here to cover both the East and West coasts! LOL

As for the TA or TAT.........
Yes, and I don't doubt for one minute that you have experience in this area. You sound very knowledgeable at/in this area!

However, I couldn't help but catch your statement in post # 11!
IMO, that could cause an inexperienced person to think that BASE is the only and main advance spec to be concerned with, and that setting Ignition timing at the higher RPM (TA or TAT) could cause poor performance from an incorrect BASE advance.

TAT on a marine gasser is very important, and IMO, much more so than BASE, if we're splitting hairs between the two!
That's all I was trying to convey here, David......... no offense intended!:)
 
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