Ignition System Question

saltydogjeff

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So I am trying to start my boat up since it has been out of commission. I have air/compression, I have fuel to the carburetor, and I have spark. I am worried about my spark.

I have cleaned all my terminals today for the ignition system in order to get the brightest spark possible. As I was doing this, I accidentally knocked the distributor to a different timing position that I set previously (8 BTDC). I got this ignition spark tester tool to help me, and was working with it to set my timing. When I did the timing today, I tried rotating the distributor while cylinder was at 8 BTDC. During this time, I noticed sometimes I would get spark, sometimes I would not, if I rotated it fast it could spark, it would spark only rotating in one direction, sometimes it would spark multiple times, I could not determine a pattern. I think there is something with the contact between the rotating deal and the spark plug wire connection. I need to check my other cylinders to determine if it is specific to that one. I also need to try and clean that contact up some more.

So, this is really more of a "what's going on" question? I think I got the problem nailed but am I missing something with points or like the condenser? I thought I could basically set it at one point and start getting the "pop - pop - pop" from the spark right in one spot.

Condenser is new, that rotating thing is new, and battery needs some charge, and I am going to try to switch to a fully charged battery and try again. Be back with more information.
 

Scott Danforth

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How are you setting your timing?

By your post, I assume you have points. Turning your dizzy back and forth with engine off, and key on will get you a spark every time you open and close the points.

With points, you first set dwell, then adjust the timing at idle in the water.
 

saltydogjeff

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With key in run position: 3.06V (+) to ground, 0.25V (-) to ground. 9.0kohms (+) & (-) to distributor, and 0.4 ohms (+) to (-) coil.

Put fully charged battery in, cleaned inside distributor terminal posts, no spark.
 

Scott Danforth

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Your voltage to the coils should be 12 volts while cranking (i terminal on starter or starter pilot relay should feed coil during ceanking). When running, either a balast resister or a resister wire will drop the voltage to about 9 when running to not burn up the points.

The negative side of the coil is fed by the points.

Back to my question. How are you setting your timing? I will add, how did you set the dwell?
 

saltydogjeff

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Sorry for missing your first post. I first set the timing by setting the position of cylinder #1 at 8 BTDC. I then placed the distributor at a position that seemed to be consistent with this location. I then rotated the engine over by hand with the crankshaft checking each cylinder as it fired, 1-3-4-2. Today, I thought I could skip rotating the engine using the crankshaft and place it at 8 BTDC and then rotate the distributor til it sparked.

I do have a meter to set dwell. I am also currently pretty short on hands making it difficult to be at the ignition switch and read what's going on at the engine. I reviewed my starting circuit which receives 12 volts. I think the 3.06 volts is pretty low for the run position.

My mercruiser manual says dwell should be set between 28 degrees and 34 degrees. Also, the timing for idle RPM has written 4 degrees in lieu of the 8 degrees which is marked out.
 

saltydogjeff

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Maybe I was turning the distributor and not opening and shutting the points?

Also, the engine is not running, so I should use a feeler gauge to set the dwell?
 
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saltydogjeff

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I was reading voltages while starting and had 8.7 Volts at the slave solenoid input, 9.5 volts on the output when key in start position, 9.5 volts to the input and output of key switch while in start position. I must have some resistive connection in the system that has a 2.5 volt voltage drop.
 

stonyloam

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OK, a little about how it works: the coil is a step up transformer, 12v in 20,000v out. there is a cam on the distributor shaft that opens and closes the points. When the points CLOSE current flows to the + terminal through the primary windings (few) of the coil to ground through the closed points. This current flow creates a magnetic field which exists as long as the current flows. When the points OPEN the current stops, the electromagnetic collapses and generates very high voltage in the secondary windings (many, many) which are attached to the center terminal of the coil. This voltage is fed through the center wire to the rotor (rotating thing ;) through the carbon button in the cap. If your timing is right the spark jumps the gap from the rotor to the correct spark plug wire terminal and travels to the plug where it jumps the plug gap to ground giving you ignition. The dwell is the length of time (in degrees of rotation) that the points are closed allowing the coil to charge. Too short and the magnetic field will not build to its maximum and you get a weak spark, too long and too much current flow and the coil could overheat. You can set the dwell initially with a feeler gauge, but you need a dwell meter and timing light to get everything correct. You can set the gap correctly but the dwell could be off because of ware on the cam and points cam follower. You were getting spark when you turned the distributor because you were opening and closing the points by turning the distributor cam.
 

saltydogjeff

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I see how it is suppose to line up.

There are a couple of different things going on at the same time. You are trying to get high voltage for spark but not all the time which would overheat the coil - hence the points. There is dwell angle associated with this part, which it seems with a dwell angle of 28-34 degrees, 4-cylinder engine, 62-56 degrees open points, then its like a 2:1 ratio open to close. Then there is that whole part of lining up the high voltage to the correct spark plug during engine rotation while you have the high voltage (1 in the 2:1 ratio) in the coil.

Now, I am looking at my ignition timing, and it would make sense that the rotor would follow the maximum dwell gap. In other words, you would have your most likely non-grounded case when the gap of the open points is the highest and the rotor is at dead center of the spark plug wire terminal. In actuality, the rotor is in advance of the largest gap portion by 10-15 degrees (? ish). I have the feeling that the engineers probably saved that for high RPMs. But, I am getting ahead of myself.

Now, I am just having a tough time trying to trouble shoot this thing, because it is difficult to tell if there is an issue with my wiring, or I am just not doing good at this timing thing.
 
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Scott Danforth

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You need a tach/dwell meter to set the points and a timing light to set the timing.
 

stonyloam

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Hmmmm..... OK little confused by your first statement, but when you feed power to the coil you will never get a spark unless and until the points open. As for the gap, it makes absolutely no difference how far the points open, only WHEN the points open. Under ideal conditions if you set the gap correctly the dwell will be close, but you need the dwell meter to set it correctly. If you are trying to set the timing without a light you could try this: make a mark on the side of the distributor at the center of the number 1 plug wire, remove the cap. Turn the engine over to bring it to TDC by lining up the timing marks. The rotor should point toward your mark, if not turn it over again (the distributor rotates once for every two times the crankshaft rotates). Turn the distributor so that it points exactly toward your mark. Your distributor rotates clockwise, so to advance the timing rotate the distributor slightly COUNTERCLOCKWISE. should be close enough to get it started and as Scott says get a timing light and dwell meter to get it right.
 

saltydogjeff

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I think my issue is with my voltage. I have been looking at the voltage readouts and it was approximately 9V for the STARTING circuit. It needs to be a full 12V. I just replaced the connection to the shift interrupter switch, which looked more or less like the picture below. I thought this could be my resistive connection. Other than that, I started reading the voltage to the (+) coil side, which started at ~12V when I first had the battery ON and the key in the RUN position. After replacing the shift interrupter connection I checked the voltage again, which read ~5V. The voltage continued to dive and I stopped reading at ~4.75V. The resistance wire was heating up which I think did it, but this is still a low voltage. I felt the resistance wire which confirmed my suspicion. I checked and remade the connections from the choke to the (+) coil yesterday. I do not know how long it will dive for, or if that is even correct? Should I replace the resistance wire with a ballast resistor to reach a steady 9V during all times of operation?

I have not checked the STARTING circuit since replacing the shift interrupter switch, but I HOPE it reads 12V.

 
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stonyloam

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If you were reading the voltage when the starter was turning, you will not get 12v, you will get battery voltage. During starting the huge current draw of the starter drops the battery voltage, so 9v is OK. Your shift interrupt should switch should be open at all times except when you are trying to shift OUT of gear while running with the boat in the water. It should have no impact on starting the boat. Read this: http://forums.iboats.com/forum/engi...3-how-to-how-the-shift-interrupt-system-works No you do not need to replace the resistance wire. you seem to be worrying about the wrong things. You need to check to see that your timing is correct and that your points are functioning properly. I would disconnect the shift interrupt switch while you are troubleshooting just in case it is shorting your coil to ground.
 

Scott Danforth

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I think the issue is over thinking the points ignition. Points file on the points to remove oxidation, set initial gap at .015 - .018" use dwell meter to adjust dwell to factory spec. Lock down points

Install rotor, turn dizzy so rotor points to #1 tower on cap. Fire motor, fine tune with timing light, lock down dizzy clamp

Dwell meter will tell you instantly if you have a problem

You can also use a test light across the two coil connections to see if your points are opening and closing
 
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saltydogjeff

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I got the engine fired up with an electronic ignition module (Pertronix) that I had. I did not use it previously but had it stowed away because I had too much going on to really think about it before firing up the engine. Now my issue is either a cracked block or leaky head gasket :blue:. My coolant will not stay in the reservoir. Going to break down and take a look in the next couple of days. Future to be foretold - fingers crossed.
 

stonyloam

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If you are loosing coolant, do a compression check. If that is OK, then probably not your head gasket. Go to Autozone and borrow the cooling system pressure kit, and see how it checks out. If the head gasket is OK, then most likely the exchanger, or the exhaust elbow gasket.
 

saltydogjeff

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I did lose coolant slowly over about 3 days. I did the compression check before I got the motor running, and it was 90-90-90-70 for 1-2-3-4. I found confidence in those numbers to continue.

I drained the oil yesterday and it came out coffee color. It was not enough volume to be the coolant and oil all together. So, I let the drain drip into a pan overnight, which I saw it pooling yesterday before night fall, to see what comes out. I am going to drop a glass of water into the reservoir today to check it out. Really no issues upon initial fill, but after initially running it, the coolant started to drop. I am going to start taking it apart again and clean up the cylinder heads and check for cracks. I really don't think I got enough cleaning, mirror like finish to put on the cylinder head gasket.
 

saltydogjeff

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Checked heat exchanger during flushing of coolant system and all seemed to check out. It is definitely going towards the oil.

The elbow was leaking a little bit of raw water, but I stopped it up tightening on the 4 bolts.
 
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