Puzzled - Ignition

[John Turney]

The Healey has been sitting since late Fall while we've had the holidays, rain and a few repairs/upgrades not involving the ignition or fuel. Those are done and we have a break in the rain, so I decide to fire it up and do some other tests. Battery charged, boot switch on, key on, fuel pump ticks and stops as the bowls are filled. Press the starter, engine turns over just fine, but no start. Not even a hint of firing.

Some additional background: The engine is a later 3000, but not BJ8. I have a Crane XR-700 trigger replacing the points, etc. I have a Sports Coil, and Bumble Bee (BB) ignition wires.

The lack of even a hint of firing makes me think it's ignition. I put my timing light on the wire for plug #1, and no blinks. I put the timing light on the wire from the coil to the distributor and it happily blinks away. Primary circuit and coil are fine. Problem should be in the HV section of the distributor.

Put on a new Advanced Distributor rotor. No change.
Put on a new cap from the UK where the manufacturer, Commercial Ignition, is not embarrassed to put their name on it. No change. Thought about putting a spare Chinese no-name cap on, but couldn't bring myself to put that pos on.

I put the timing light on the other five plug wires, no blinks.

I pull the wire from the coil to the distributor out and measure the distance spark will travel from the end of the wire to ground. I get a hot spark of least 6 mm, which exceeds the spec of 5 mm.

I pull #1 plug and see if I have a spark between the electrodes. I get a weak spark. Plugs are gapped at 0.030", as recommended with a Sports Coil and Crane XR-700 primary system. Try 0.025". No change.

I measure the total resistance of the BB plug wires and plug caps (where the resistance is) and get 13 k to 15 k Ohms on all. BB plug wires look fine.

I try a new BB wire from the coil to the distributor. No change, except the black stripe on the wire is wider.

I try a non-resistor wire and plug cap to plug #2. Still no blink.

I'm running out of ideas.

 

[Marvin Gruber]

Sounds like rotor button, had same issue last week. Put an old one back in and fired right up.
Marv

 

[johnea]

John, I'd suggest to remove the dizzy cap, pull the centre lead from the cap, hold it close to the rotor and crank the engine. When there's a spark your rotor is cracked.

 

[vette]

I was going to suggest the rotor button at the center of the cap as well. Are you sure it is still there. Get new button or new cap.

 

[John Turney]

Yes, the rotor button there, and the spring is good.

 

[dklawson]

There have been a number of reports over the past few years of poorly made rotors that short out once installed. The short is "internal" and connects the dizzyshaft to the spot where the carbon brush rides. Being internal it cannot always be seen. It certainly would not hurt to try another rotor.

 

[RAC68]

Hi John,

I also using the Crane XR700 electronic ignition with optical trigger and have been very satisfied with its performance and reliability. However, about 15 years ago, I was using its Allison predecessor and experienced a similar failure that turned out to be in its optical trigger (Crane purchased Allison and honored the Allison replacement guaranty). When experiencing the trigger failure, the car just stopped and would not restart.

Previously, I had created a kit of parts I had tested for my points setup. Since so many parts could also cause these conditions, I reverted to the known good points setup and found the car would start, validating all other ignition parts as good and narrowing my Allison electronic ignition as questionable. With the trigger out of the car, I closely examined the optical trigger unit located within the distributor and noticed some marks on the housing but could not tell if there was a problem with this unit. After a call to Crane for additional diagnostic procedures, I concluded this to be my problem and after installing a replacement, have had no further issues since.

Today, the quality of replacement ignition parts is questionable and many ignition parts could cause the same symptoms. However, I carry this same tested points setup that I, only recently, was considering if it was really necessary to continue carrying ... and decided to continue.

Not wanting to add to the possibilities but I hope this helps,
Ray(64BJ8P1)

 

[Keoke]

John, I'd suggest to remove the dizzy cap, pull the centre lead from the cap, hold it close to the rotor and crank the engine. When there's a spark your rotor is cracked.

Good suggestion.

However, Hold the center lead close to the brass arm but not touching, if you get a spark to the arm the rotor is cracked.

 

[dklawson]

In his first post John has confirmed that he is getting spark when the disconnected coil wire is held up to 6mm off of ground. That says both the coil and the Crane unit are working.

 

[vette]

I agree with Doug Lawson, If the coil is firing then I believe the crane unit has to be working. I believe it was said that the rotor was checked or already changed but it seems to me that it has to be the rotor, cap or rotor button.

 

[Keoke]

Vette:

Just run johnea 's test

 

[John Turney]

Thanks, guys!

I don't think I'll be able to get back to it until Friday, but I do have a couple of replies:

- Doug & Ray: Yes, I have spark from the coil to the distributor, so the Crane and coil seem to be fine. I really like the Crane optical pickup; that's why I use one as the pickup for my tripmeter (not the same one as on the ignition).

Johnea, Keoke & Doug: The new (as was the old) rotor is one of the rotors that is suppose to be the best, but I will check it using Johnea's method as soon as I can. Assuming it's ok, I'll test the carbon rotor button.

I'll let you know. Tomorrow I have to be away, and will be back Friday.

 

[John Turney]

And the winner is: johnea!

Actually, the rotor was fine, but as it went by where the terminal for Plug #1 is located, it would arc to the bracket for the Crane optical pickup. It was sticking up within a half inch or so of the rotor arm. I trimmed the bracket off flush with the pickup and the arcing is much reduced. Anyway, success!

Ray: you may want to check yours.

Thanks, guys!

 

[dklawson]

Great! Thanks for posting what you found wrong.

 

[Keoke]

And the winner is: johnea!

Actually, the rotor was fine, but as it went by where the terminal for Plug #1 is located, it would arc to the bracket for the Crane optical pickup. It was sticking up within a half inch or so of the rotor arm. I trimmed the bracket off flush with the pickup and the arcing is much reduced. Anyway, success!

Ray: you may want to check yours.

Thanks, guys!

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