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Ignition timing with Pertronix Ignitor and strobe light

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Lutz Kramer

Lutz Kramer

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One year ago I put a Pertronix Ignitor-I Kit #ML-161 in a Mallory Distributor of my AH 3000 MK III Phase 2.

When I put it in, I did the timing manually, because it couldn’t be done with a timing light since I couldn‘t reach the appropriate paramaters given by the manual, which are 15° BTDC in idle and about 38° at about 4500 rpm. Whenever I came close to 15° the engine stalled. When I checked the timing with the strobe light I got and still get the following indications: 40° BTDC at idle and about 60-70° BTDC at 4500 rpm, which is of course way off. I can’t even believe that the engine is running with those settings.

What so ever the car has been running without any problems since then.

I know the words: „Never touch a running system!“. Nevertheless I want to have the engine running in accordance with the right parameters and of course would like to find out the reasons for this strange phenomenon.

So, I checked the mark for TDC on the pulley while the rotor is pointing at the #1 plug wire. Everything is just perfect! In addition to that, the piston is in combustion stroke and the distributor is indexed correctly and not 180° off.

Now, can anybody tell me what‘s wrong here?

I called Pertronix here in Germany and they absolutely have no idea.

The only thing I can think of would be that the coil ist producing a certain amount of power which is strong enough to create a spark while it‘s not strong enough to activate the strobe. This may be done by a second flow of power that follows the frist one right after. So the strobe would be lighting the 40° mark while the spark is already history???
I know it sounds strange, but has anybody any idea?
 
Of course it could be a poor Strobe light. But I forgot to mention that I already had tried another timing light of a friend of mine of another manufacturer. Unfotunately with the same results!
 
Well another Wild Arse Guess:

The common element here is your car so maybe the car's ignition radiation upsets the digital timing lights.???
 
Simple things first. Are you sure your pulley correctly shows TDC? Can you check the piston position?
 
Roger, I checked TDC on the pulley with the position of the piston and the pulley indeed is exactly showing TDC.

Something else I found is that the distance between the magnetic sleeve and the module on the basic plate is almost 0 mm while the guys of Pertronix Germany say it should be betwenn 0.5 and 1.2 mm. Could this may be cause the phanomenon described?
 
Lutz Kramer said:
Roger, I checked TDC on the pulley with the position of the piston and the pulley indeed is exactly showing TDC.

Something else I found is that the distance between the magnetic sleeve and the module on the basic plate is almost 0 mm while the guys of Pertronix Germany say it should be betwenn 0.5 and 1.2 mm. Could this may be cause the phanomenon described?
Click to expand...

Well it just might be as your repetitive TEST RESULTS seem to emulate an incorrect dwell time???
 
Yesterday, I pulled the distributor and put it on a bench for testing. Connceted the battery to the module and hooked up a voltmeter. Then I turned the rotor and it just worked fine at all 6 cylinder positions. Twell time also seemed to be ok.

Then I put it back in, cranked the engine and best run in idle was again at 45° BTDC!? When I turned the dizzy towards 15° BTDC the engine stalled already at 20°. So, still the same problem.

May be I should bench test the ignition system together with the coil and see whether there is a time difference between the spark and the time the strobe light fires? That would portend to a coil problem.

Any other idea is welcome!
 
Why don't you replace the Petronix with the standard contact breaker set and see if you can get her to 15 degrees at idle?
 
Chris_Masucci said:
Sounds to me like you need to index the rotor? Are you sure you are on the #1 wire?
Click to expand...

Yes, that's a good thought. Google "rotor phasing". I think MSD has videos that explain this. Don't know if Pertronix has this issue, but the MSD on my Dad's Cobra replica did, and I did the procedure for him. Made a big difference.

If the car seems to be running OK, then maybe the spark is occurring at about the correct time, but there could be something causing the timing light to trigger late(???). If you are using newer, "high-tech" lights, maybe find an older, less fancy one, and see if it shows a different advance. My original timing light from the '70's doesn't have an inductive pick-up. You have to insert a springy thing that fits snugly on the spark plug cap, and into the wire boot, then attach an alligator clip to the springy thing. Maybe the inductive pick-up, and the type of plug wires, and some kind of RF interference are messing with the timing light's measurement. Just a Wild-Assed-Guess! GL, Jim
 
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Another thought (and that can be dangerous!): Is the cam timing off (or a slack chain)? That COULD cause something like this. I'm thinking it might be off only a tooth or two. This is probably a bit of a reach, but might be a possibility. If you remove the valve cover, use a dial gauge and put some marks on the front pulley/damper. There should be valve opening, closing and lift specs that might tell you if this is the trouble. A decent repair manual might describe the procedure. Jim
 
Good Ideas Jim!
I used to have an old Bosch timing light, that had to be plugged within the spark plug and the plug wire, like you mentioned. Unfortunately it's lost. But anyhow will try to find one. The other possibility would be to visit a Bosch station here in Germany. They usually have oscilloscopes which can be used to find out what is going on in plug wire #1.
 
Jim, indeed the cam timing might be a problem, since I had changed the chain last year. But I'm pretty sure I didn't mess up the timing. I checked everything several times before I closed the chain cover again. But you never know!?
 
Chris I'm pretty sure to be on #1 wire!
But what I will do is putting back my old contact assembly like John said. This way I can find out, whether there is something wrong with the coil or the plug wires. In case the timing light would show 15° again the problem would be more or less the Pertronix.
 
Lutz Kramer said:
Jim, indeed the cam timing might be a problem, since I had changed the chain last year. But I'm pretty sure I didn't mess up the timing. I checked everything several times before I closed the chain cover again. But you never know!?
Click to expand...

I was almost bit by a mistimed cam. When I replaced the gear/chain assembly, it looked correct, until I started to install the chain tensioner on the slack side of the assembly. As the chain's slack tensioned, the cam gear rotated. Fortunately, I caught it, and aligned the assembly again with the tight side of the chain such that when the tensioner moved into the slack side, the gears stayed in alignment.

My favorite (NOT!) mistake, which happened fairly recently on my Ford appliance car, was installing one front brake pad backwards, so that the metal side was against the rotor! Fortunately, it was VERY apparent the first time I applied the brakes. Guess I was in a hurry, or just suffering from what an old boss called "Cranial Rectumitis". BTW, I've been working on cars for 40+ years, so I must be an expert mechanic! :eek:

The Bosch station's 'scope might tell you a lot. That would be my first stop, if I couldn't find an old-school timing light, and replacing the Petronix with the original points assembly didn't change things. Jim
 
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Jim 58 BN6 said:
I was almost bit by a mistimed cam. When I replaced the gear/chain assembly, it looked correct, until I started to install the chain tensioner on the slack side of the assembly. As the chain's slack tensioned, the cam gear rotated. Fortunately, I caught it, and aligned the assembly again with the tight side of the chain such that when the tensioner moved into the slack side, the gears stayed in alignment.

My favorite (NOT!) mistake, which happened fairly recently on my Ford appliance car, was installing one front brake pad backwards, so that the metal side was against the rotor! Fortunately, it was VERY apparent the first time I applied the brakes. Guess I was in a hurry, or just suffering from what an old boss called "Cranial Rectumitis". BTW, I've been working on cars for 40+ years, so I must be an expert mechanic! :eek:

The Bosch station's 'scope might tell you a lot. That would be my first stop, if I couldn't find an old-school timing light, and replacing the Petronix with the original points assembly didn't change things. Jim
Click to expand...

As far as I remember I did the timing of the chain in accordance with the manual by counting the chain links between certain marks on the cam gear and the crank gear on the opposite side of the tensioner, but I can't remember the number of links anymore. As soon as the tensioner starts to work it is true that the cam gear may be moved but also the crank gear is moved without any lack since the crank gear is pulling at the chain on the non slack side which is therefore always taut. So as long as one counts the right amount of chain links, the timing should be perfect.
 
Today I pulled the Pertronix and put in the old Mallory twin contact plate. Leaving the dizzy at the same position as before the timing light pointed at 35° BTDC at idle instead of 45° with the Pertronix but still far off from what is supposed to be normal (15°).

I believe the next step is to visit Bosch!
 
Clearly the car is not running with such exaggerated advance, so if your pulley is correct, something is wrong with your measuring.
So changing parts on the car is probably not going to fix It! The Mallory plate being different from the Pertronix is not so surprising.
 
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