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3 liter timing problem

R

Rspen

New member
I am about to give up and pod this thing.
My 3.0 liter EST ignition won’t come out of base timing when the jumper is removed and the shift interrupt switch is reconnected. The timing does advance though when the rpm’s are raised. At 5-600 rpm it stays at 1 deg ATDC as per the manual after removing the jumper etc. When I raise the rpm at the carb, it goes up by itself after a slight turn of the set screw and the timing advances to 6 deg BTDC and settles at about 1200rpm. When I turn down the rpm it hits a point where the rpm goes down to the 5-600 rpm and the timing reverts to 1 deg ATDC.

I’ve changed out the module 2 times. New plugs, wires cap and rotor. New pick up coil. New ignition coil twice too.

New development - the Dash tach has stopped working and the shop tach output doesn’t light a shop tach.

Any help would be so welcome.
 
Rspen said:
I am about to give up and pod this thing.
My 3.0 liter EST ignition won’t come out of base timing when the jumper is removed and the shift interrupt switch is reconnected. The timing does advance though when the rpm’s are raised. At 5-600 rpm it stays at 1 deg ATDC as per the manual after removing the jumper etc. When I raise the rpm at the carb, it goes up by itself after a slight turn of the set screw and the timing advances to 6 deg BTDC and settles at about 1200rpm. When I turn down the rpm it hits a point where the rpm goes down to the 5-600 rpm and the timing reverts to 1 deg ATDC.

I’ve changed out the module 2 times. New plugs, wires cap and rotor. New pick up coil. New ignition coil twice too.

New development - the Dash tach has stopped working and the shop tach output doesn’t light a shop tach.

Any help would be so welcome.
Click to expand...
Where are you getting your modules from ? If dash tach is malfunctioning disconnect it from coil signal wire to test if that is affecting it. If you throttle up how much advance do you get at 2800 rpm ?

Is it possible it’s not going into base and your set idle to 1 deg atdc ? If it is advancing as rpm go up set the total to25-28 what ever it should be and let the idle twining fall where ever it does
 
Modules are Merc parts. I'm not exactly sure what the total advance is at 25-2800. I understand what you're saying though. Would it do the same thing with idle timing at 6 degrees BTDC?
 
Took Dieter's advice and set the timing at what looked like 25deg BTDC. Hard to be exact as the timing tab only goes to 8. So tried for 3x the tab. When I brought it down to 800 rpm timing went to approx 15deg BTDC. It did not go back to the 2deg ATDC as it did before. I'm going to take it out today and see how it runs. If this works - it begs the questions - How do I accurately time it at 25-2800 (whole reason to do it at base timing in the design I'm sure) and why won't it go in to base timing when the neutral safety switch is bypassed and the two wires at the distributor are jumped?
 
You
don't time it at 2400 rpm, your checking to see if timing advances 12* at 24 to 2500 rpm.
I won't be able to look up your serial nu.ber till tomorrow but maybe someone else can verify timing spec
 
1. I would not reccomend having 15* BTDC as timing at idle.
Idle should be 650-750rpm in gear.

In order to properly check advance you either put timing tape on balancer or get a timing light with timing advance capability.

The reason for full advance at around 2800 rpm is, most engines and ignition timing control systems develope full advance at or around 2800 rpm.

Every engine has a max timing specification more or less.

Initial + advance = total.

Before you go messing around and before you use it on the water. You need to find out what that engine max advance is specified.

Lets say the max timing spec is 28-30 BTDC (initial + advance). You have now 15 initial, lets say the timing control adds another 20* advance. That would put you at 35* total.
That 5* above specification. Possibly causing detonation and damage a piston or cause excessive heat to build up in engine.

I would gather the engine timing specs and get a timing light with advanve ability and redo this before using it.
 
1000004029.jpg
 
Ok. So the timing advance is small. And the graph shows 15 btdc

So it appears your good to go.

One thing, Many use a timing light with advance capability and rev engine to about 2800-3000 and set distributor to achieve max timing and dont bother with base. So your guestiment worked on the approx max timing
 
One last thing.
Many here work with V6 and V8 so the base is typicall 6-8* btdc and timing advance is around 22-24* so max would be approx 32*BTDC....
I myself rarely deal with 4 cyl timing issues. I was suprised to see such a small advance of what, 12*. Interesting!
 
I take your advice to be more accurate than trying to estimate total advance with no mark with my head hanging down in the bilge neck craning to see the mark. Picking up a timing light with advance tomorrow and checking to see how my estimate was.

Still would like to know why it's not going in to base timing. I have 12volts at the module from the shift interrupt. Anything else I can check?

Wondering if I have wiring issues as the tach stopped working too. Life with old boats.
 
In post #5 you say the following:
....and why won't it go in to base timing when the neutral safety switch is bypassed and the two wires at the distributor are jumped?

Are you jumping the neutral safety switch or shift interuptor switch?
 
Rspen said:
Took Dieter's advice and set the timing at what looked like 25deg BTDC. Hard to be exact as the timing tab only goes to 8. So tried for 3x the tab. When I brought it down to 800 rpm timing went to approx 15deg BTDC. It did not go back to the 2deg ATDC as it did before. I'm going to take it out today and see how it runs. If this works - it begs the questions - How do I accurately time it at 25-2800 (whole reason to do it at base timing in the design I'm sure) and why won't it go in to base timing when the neutral safety switch is bypassed and the two wires at the distributor are jumped?
Click to expand...
I have seen this used as a work around if it wont go into base mode, which some folks seem to have issues with certain modules and or boats. Also if it doesn't advance you have a bad module, which again anecdotally on forums you see from time to time.

When locked in base you set it to 2 adtc, and the max should fall within 25 give or take. at idle will be around 12-15. If you cant get it in base, just set the max total advance. Otherwise I think the way you had it you were 10 degrees retarded. Best to get a advance timing light or timing tape on balancer, or make your own marks as the entire circumference of the balancer is 360 degrees...
 
kghost said:
One last thing.
Many here work with V6 and V8 so the base is typicall 6-8* btdc and timing advance is around 22-24* so max would be approx 32*BTDC....
I myself rarely deal with 4 cyl timing issues. I was suprised to see such a small advance of what, 12*. Interesting!
Click to expand...
I think at some point they had head gaskets blowing as started using 2 deg ATDC vs like 4 or 6 before. I think this may have been in the late 80s...

I think both the 3.0 and 4.3 dont get a lot of total advance. Makes sense with more detonation potential under load than a car. With 135 hp how much are yu going to gain for 3-4 degress more timing....
 
Two items to add - regarding the timing marks, you can measure its diameter and use the arc length formula to determine where your MAX timing mark goes and use a 'plain' timing light - just make sure you get it on the correct side of the TDC line.

I noticed that two (of the three) timing curve charts in the factory manual are wrong in that they shifted the curves the wrong way when creating them (my best guess). They are also rather unique in that they show the total advance vs just the advance generated inside the module.
 
So I got a degree adjustment timing light and set the total timing at 2600 rpm to 26 degrees BTDC.

When I idled it down to 1000, the timing went to 0 degrees at 800rpm. It was supposed to go to 15 degrees BTDC.

Tried again to time it in base timing - no joy.

Any other ideas are extremely welcome.
 
Rspen said:
So I got a degree adjustment timing light and set the total timing at 2600 rpm to 26 degrees BTDC.

When I idled it down to 1000, the timing went to 0 degrees at 800rpm. It was supposed to go to 15 degrees BTDC.
Click to expand...
I don't see a problem
 
Isn't the timing supposed to fall back to 15 degrees BTDC at 1000 rpm as per the curve chart? Not 0 degrees and run like crap?
 
You should be timed at 2* ATDC
Your getting 28* of advance total timing and is good

It's not going back to 12 to 15 most likely because something is wrong with your reading or initial timing procedure. The EST module only provides so much timing no matter what engine it's installed on. Your getting good advance (based on 2* ATDC) so something else is going on when idling
 
Any ideas what is going wrong at idle? When I adjust the idle up it goes up by itself because the timing advances. Idle down and it goes down as the timing retards.
 
The internal ( to the module) timing curve is rather steep and I wouldn't expect to see what is shown on the plot much below 2000 rpm...I would also be really surprised if you got 28 deg of advance out of a module on a 4 cyl...
 
But that doesn't explain why the timing goes to 2 degrees ATDC when the jumper is removed and the shift interruptor is reconnected. The manual says it should go to 6-8 degrees BTDC and stay there at idle. Not go down to 2 degrees ATDC at 450rpm. That's my problem.
 
Since I can't see your boat, I can only assume you have the correct switch installed. A search by serial number calls up 3 installations but 1 specifies a higher serial number than yours. And the other 2 each use 2 different styles.
All that being said I believe your switch has round mounting holes and not elongated mounting holes. If I am wrong & you have elongated mounting holes it may be possible it's mounted too close to the fork?

Read below carefully & don't take offense. I do not know your experience level.

THE SWITCH SHOULD NOT BE DEPRESSED EXCEPT DURING A BRIEF PERIOD (MOMENTARILY) WHILE SHIFTING FROM GEAR INTO NEUTRAL. IT SHOULD NOT DEPRESS EVEN BRIEFLY WHILE SHIFTING INTO GEAR. IT SHOULD ALWAYS BE RELEASED (NOT DEPRESSED) WHILE IN GEAR OR IN NEUTRAL.

*** Is the shift cable properly adjusted so the interuptor switch is in the bottom of the V and not being depressed while in gear or in neutral?

*** Is the cable binding so as to not return to the bottom of the V when in gear or in neutral?

*** Did this issue just start suddenly? Was it intermittent and progressively get more frequent?

*** Did you recently buy this boat or own it prior to this issue?
 
Hey Droid - no offence ever taken when you're asking for help.

I changed the switch out because a mechanic pinched it's wires between a couple of flanges of the shift brackets and it shorted out while on the water. Thank God for kickers. I installed a new one as per the manual. Have not checked the shift cable adjustment etc though. Just centered it in neutral.

Question, how would a shift interruptor switch cause the timing issue? I'm leaning towards the distributor as it's the only thing I haven't replaced and if the signal coming from it to the module is bad?????

Background - bought the boat last year as a project. Motor had a hole in the block so had the motor replaced. Hasn't run right from the beginning. Shop that did the motor think it's ok. So no help there.

Worked on cars and motors etc all my life full rebuilds etc. First boat though. I'm 60 so from 15 that's 45 years of backyard experience. Kinda new to the electronic ignition though. Petronix in my 66 mustang was pretty much it before this.
 
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