Ignition Problem Strikes Again!

I decided to take the car around the block and it would not start. From past experience, I knew I only had a few minutes to troubleshoot the cause so I started immediately.

I connected my test tool which replaces the spark plug to confirm the ignition is working. The tool clips to a ground and has an adjustable gap which the spark should jump across when trying to start the car. There was no spark.

I checked voltage to the positive side of the coil and there was 12 volts. I then disconnected the coil and check continuity between the positive and negative terminals. It was at 3 ohms which is correct for the coil.

The next step was to check the Ignitor using the procedure I published before. I tried it and there was nothing registering on the volt meter. I came in and checked the document again. I walked out and started testing it again with no result and then it started registering voltage. I connected everything back together and the car started fine.

While I really believe I was testing it properly the first time. The fact it started working while I was testing makes me think I was missing something. I'll likely just order another Ignitor as that is all I could imagine causing the issue at this point.

Adjusting the Timing Curve Further

I've been attempting to duplicate the problem which causes the engine to die randomly. I've started the Mustang and let it run at least twice a night for the entire week. The issue has not reoccured.

I decided to work on the timing curve tonight. I thought running the engine and working with the distributor parts might cause the problem to happen again. Unforatunely, I was not so lucky but I feel better about the timing curve.

When I started, my timing curve was as follows:

850 - 14 Degrees BTDC
1000 - 14 Degrees BTDC
1500 - 20 Degrees BTDC
2000 - 31 Degrees BTDC
2500 - 39 Degrees BTDC


I originally had a hard time getting the timing to increase early. Total timing would come in earlier with the new springs I purchased but not as early as had been recommended.

I worked on bending the mount tabs for the springs and actually switched to use one slightly stiffer spring. I basically use a light spring to control early movement. The stiffer spring is looser and keeps all the timing from coming in too early. This resulted in the following:

800 - 14 Degrees
1000 - 18 Degrees
1200 - 22 Degrees
1500 - 24 Degrees
1800 - 26 Degrees
2400 - 34 Degrees
2600 - 37 Degrees


The comparison of the two timing curves looks as follows:


The new timing curve works a little better than the previous curve. With a base timing of 14 and the reluctor arm set to 10L, I should not have more than 34 total degrees of advance. However, I set the timing light to 34 and reved the engine and it passes 34 to about 37 or 38.


When it reaches the 37 or 38 number, the timing seems to bounce around more. I'm not sure if this is because of the quality of the original distributor or something else. It could be cross fires across cylinders since the distributor cap is small.

Ignition Problem Strikes Again!

When driving 70 MPH yesterday, I noticed the tachometer read 2,600 RPM. With a 25.5" rear tire and the new 3.25 gear, I should run near 3,000 RPM at 70MPH. This would lead me to believe the new 18 tooth speedometer gear is not correct. I asked my wife to follow me around the block so we could see if the speedometer is indeed off and if so by how much.

I started the Mustang to warm it up and it died after about two minutes. I tried to start it again but it would not start. I immediately started troubleshooting parts as I know from past experience this intermitent problem does not last long.

I disconnected a spark plug wire (#5 cylinder) and connected it to a test tool. The test tool connects to a ground and has a small, adjustable gap. If the ingition is working, you can see the spark jump across the gap. This was not occurring so I know the problem is ignition related.

I then grabbed the spare coil from the trunk and installed it in the car. I left the spark plug tool in place and tried to start the car. I still had no luck starting the car and no spark. The only thing left are the components inside the distributor (primarily the Ignitor I).

I was not sure how to check the Ignitor. After a few minutes, I tried to start the car and it started just fine. I searched the internet and found the following image which contains the test procedure for an Ignitor. If I can get this to happen again, I'll test the Ignitor.

I'm ready to begin driving the Mustang again. This has me tempted to go ahead and buy a replacement Ignitor points conversion kit. However, there is now an Ignitor I, II, and II kit. Each works best with a different coil which stinks as I just purchased the one which works best with an Ignitor I.

I considered buying a new distributor but most are billet and would look entirely out of place. My distributor currently in the Mustang is not original to the car. The part number for the distributor is F3OF-17127-HB. The part number for the correct distributor is C7OF-12127A.

Adjusting Ignition Timing

I've been posting a few technical questions on a new forum I found for engine builders. I posted about how the car seems to take off at 3000 RPM but hesitates and does not perform very well below 3000 RPM. The responses I've received suggest it is because of my timing.

I posted the mechanical advance curve I posted to this blog a few days ago:
850 - 11 Degrees (my initial advance) BTDC
1000 - 13 Degrees BTDC
1500 - 17 Degrees BTDC
2000 - 25 Degrees BTDC
2500 - 31 Degrees BTDC
3000 - 38 Degrees BTDC

I was told a better curve would be as follows:
850 - 18 Degrees BTDC
1000 - 24 Degrees BTDC
1500 - 32 Degrees BTDC
2500 - 36 Degrees BTDC
3000 - 38 Degrees BTDC

I'm a little concerned about using 18 degrees initial timing. Most engines with 9.5:1 compression ratio create the most power with between 38 and 42 degrees total timing. It is recommended that all of this timing come in by 2500RPM. In order to make this happen, I need to switch the advance mechanism in the distributor from the 15L (30 degrees advance) side to the 10L side (20 degrees advance). If I then set my initial advance to 18 my total would then be 38.

I switched the internals parts of the distributor tonight. When you switch the side of the arm used, the distributor is 180 degrees out. I pulled the distributor and put it back in back in the correct alignment. It took a few minutes to get the timing set perfectly but it worked out.

My base timing is currently set at 16 degrees. I tested the rest of the mechanical advance with the vacuum line plugged. I recorded the following results:
850 - 16 Degrees BTDC
1000 - 16 Degrees BTDC
1500 - 23 Degrees BTDC
2000 - 34 Degrees BTDC

I stopped at this point as it is 9 o'clock and I needed to put the kids in bed and did not want to wake up the neighbors kids. I'll need to work on it a little more tomorrow night. I would prefer to have more advance earlier but also space out how the advance is applied. I'm not sure of the best way to do this so I'll need to research and experiment some.

09/19/09 Edit: I've been working on the timing curve a little more. I'm not sure how to change it much more as the only adjustment left after switching to light springs is to bend the tabs they attach to. However, I was able to adjust and test it and found the following:
850 - 14 Degrees BTDC
1000 - 14 Degrees BTDC
1500 - 20 Degrees BTDC
2000 - 31 Degrees BTDC
2500 - 39 Degrees BTDC

I'm not sure how I reached 39 degrees advance since I have 14 initial and 20 mechanical. This should limit me to 34.

Ignition Timing Check

I tested my ignition advance on Saturday morning. To test it, I removed the vacuum tube from the distributor and plugged it with a golf tee. I then used a timing light to check the base advance and the mechanical advance at a few RPM points. I recorded the following:

850 - 11 Degrees BTDC
1000 - 11 Degrees BTDC
1500 - 15 Degrees BTDC
2000 - 23 Degrees BTDC
2500 - 29 Degrees BTDC
3000 - 36 Degrees BTDC

With an initial timing of 11 degrees and the 15 degree plate in the distributor, my total advance should be 41 degrees. I did not check the advance at 3500 RPM but I'm sure all 41 degrees is present by that point.

To get better performance, I could replace the other stiff, stock spring with the light version I received in the kit. This would provide all the advance by around 2800. Since I cannot change my vacuum advance settings, I'm concerned this could result in pinging which I would not be able to correct. Since this works well, I will leave it alone for now.

Ignition System Upgrade

I removed the distributor cap and top plate today. I wanted to check the internal parts to determine how much mechanical advance was possible. I found a 15 degree arm installed which would provide 30 degrees over the base timing.

The RPM at which the timing increases is controlled by two springs. The stiffer of the two springs was stretched and did not fit properly on the mounting points. The other spring fit well but had less resistance. I'm going to replace these springs while I have the distributor apart. The new springs should allow for full advance by 2800 RPM.

I tried to locate new springs all over the city but no one sells them. I ordered them from Summit with a new coil and some spark plug wires. They should arrive by Friday and I'll install the parts this weekend.

I hope the additional advance corrects the hesitation I feel when accelerating.