Dizzy cap/rotor gap

Standard & electronic conversions

Dizzy cap/rotor gap

Postby FMuscle » Tue Jul 26, 2016 11:01 am

I recently bought a complete late type (push type) ignition setup to replace the side entry leads on my 948. I also went and bought an accuspark stealth electronic ignition module.
I fitted everything minus the module (minor modification required) and tried to start the car. Nothing. I put back the old cap and leads on the new rotor, carefully push the screw-in king lead into the push type coil, and it starts right away.

I measured the distance between opposing contacts in the cap, old one 44.66 mm, new one 45.68mm. Would that 0.5mm gap on each side really be enough to prevent the engine from running? The gap in the plugs is bigger than that!?

Or could it be a faulty cap? I have never seen a "new" faulty cap before...
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Re: Dizzy cap/rotor gap

Postby Panky » Tue Jul 26, 2016 12:55 pm

They usually wear away more than that. Do the contacts in the side entry cap sit at the same height as those in the top entry one? Is the locating lug in the new cap in the same place as the old one so it sits in the same place in relation to the contacts. Is the carbon contact in the top of the cap long enough to reach the rotor arm, just throwing a few ideas in.
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Postby FMuscle » Tue Jul 26, 2016 1:05 pm

I checked the distance from the base of the cap to the end of the cut-outs on the contacts and it's the same on both. Same position. I did use emery paper on the center contact (but haven't tried it yet) and I noticed a mark on it, so I assumed it was from the rotor turning when I was cranking. I will double check that and whatever I can think of...

*Edit*
Still no start. Tried flipping the king lead around, put the angled end on the coil, nothing. But I know that the rotor touches, I got another mark on the contact... I'm speechless...
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Re: Dizzy cap/rotor gap

Postby bmcecosse » Tue Jul 26, 2016 7:50 pm

The centre contact is a spring loaded carbon rod. Sure you have the plug lead order correct with the new cap? 1342 anti-clock round the cap. Are there any sparks at the lead ends - maybe the contacts are radially set differently to the old cap - so the rotor is not opposite a contact when the points trigger the spark.
 









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Postby FMuscle » Wed Jul 27, 2016 11:50 am

Yep the order is right, I know a 4 cyl firing order by heart, and it's confirmed by the cast stamp on the exhaust manifold... I should receive my spark tester tomorrow, that will make it easier to check by myself, as I can't be cranking and doing the screwdriver trick at the same time.

To be fair, I find this very, very odd. A test light showed the power going from the coil end of the king lead to the inner centre contact.

The only thing I can really think of would be the timing, I will try to get a test light from work if we have one to check it with the old cap.
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Postby FMuscle » Sat Jul 30, 2016 3:53 am

Oh well....


Issue just got bigger.

I was just starting work, I checked resistance of the leads through the cap, the king lead on the old cap has 15,000Ω as the new one only has 5,000Ω. But two things to point out, the "old" king lead is a new generic one I put on to get the car running again while I waited for the new stuff. And the plug leads have less resistance on the old setup. 5,000Ω vs 6,000-10,000Ω depending on length on the new ones.

Then I fitted the old cap on to check the timing with a timing light. Start attempt one, cranking a few seconds then starter spins disengaged. Try two, cranking then a "tonk" noise heard. Third try, ignition light dims but nothing moves... :? I checked if power reached it, and it does.

Removed the starter bolts, it won't bulge out. The workshop manual says clearly "The starter can be withdrawn without difficulty.". It does not. It is, according to that chapter, "an indication is given that current is flowing through the starter windings but the starter is meshed permanently with the geared ring on the flywheel." So I tried to turn the engine with the crank handle and by rocking the car while in gear to dislodge it. The engine is not turning even by a hair.
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Re: Dizzy cap/rotor gap

Postby Custard » Sat Jul 30, 2016 12:26 pm

Is there a square on the back of the starter motor?

Sometimes moving that will move the pinion out of mesh, but don't force anything.

Sean.
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Re: Dizzy cap/rotor gap

Postby BLOWNMM » Sat Jul 30, 2016 12:36 pm

Hi Guys
The starter motor rotates anticlockwise when viewed from the front to turn the motor clockwise. Use a spanner on the square end of the starter shaft (sometimes this is covered by a removable cap) and turn the starter shaft clockwise. This should unlock a jammed bendix drive.
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Re: Dizzy cap/rotor gap

Postby bmcecosse » Sat Jul 30, 2016 7:36 pm

Rock the car in gear to free the starter. Put everything back to as it was before. You seem to be making matters worse!
 









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Postby FMuscle » Sun Jul 31, 2016 4:22 am

bmcecosse wrote:You seem to be making matters worse!


No SWEARING MODERATED... I won't be defeated.

Rocking the car was the second thing I tried after the crankhandle. If that rare weird phenomenon of water falling from the skies stops I will try the square end on the starter. Sucks that I have limited tools at home and a less than ideal working space.
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Postby FMuscle » Sun Jul 31, 2016 12:16 pm

I got the starter out. Thanks to Sean and Bob for pointing the tip.

I was running out of time, so I couldn't test properly, but I believe the car will start now. A few spins with the hand crank and promising sounds were heard (yes, with the new cap and leads). The starter is coming to work tomorrow to be bench tested and cleaned, I want to make sure it's in good shape before refitting it.
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Re: Dizzy cap/rotor gap

Postby Custard » Sun Jul 31, 2016 6:04 pm

Good man.

If starter all seems fine on the bench, I would test with the battery on the car before fitting.

It could also be sluggish if the "engine" earth strap is in poor condition or loose.

Engine earth strap is actually back on the gearbox and is braided so can deteriorate one strand at a time.

Sean.
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Postby FMuscle » Tue Aug 02, 2016 11:04 am

My starter is fine and back in.

I found out that I have fire reaching the plugs, but the spark isn't strong enough, a bad dark orange shade of spark. Another test was done, Voltage/drop.

On ignition, battery has 12.25V
On the coil connections 11.55V
Positive drop is 0.15V
Negative drop is 0.55V

(Sean) I will change that grounding strap shorty, when I do the rewire. But since I have spark, I plan to look further into the dizzy. Anyone knows how to measure the actual contact/rotor gap without special tools?
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Re: Dizzy cap/rotor gap

Postby Custard » Tue Aug 02, 2016 12:01 pm

The grounding strap was really if it turns very slowly on the car but not on the bench.

If it is struggling to turn then it will be taking power and the coil could be losing out.

You could try a lead from the coil to a plug if there is no change that rules out the distributor cap and rotor.

I just read the thread back and can't figure out if you are running the electronic module now or points and a condenser.

I think you get an orangy spark that is longer in duration if the condenser is not working because you get arcing at the points as there is not a clean on/off to the spark. Also if on points it is worth rechecking the wiring and adjustment. I have had some pattern ones that are a right pain to get the wires on without shorting, and awkward to set without moving when the screw is tightened.

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Postby FMuscle » Tue Aug 02, 2016 12:13 pm

still on points for now, I keep forgetting my drill at work to make the hole for the wires in the plastic blank. I did move it all out to fit the electronic module before I found out the existing holes met with a metal plate in the dizzy :shock: I put everything back, and it did start afterwards with the old cap..
I'll try to bring my drill back tomorrow.
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