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Discussion Starter #1 (Edited)
Editing in case this can be helpful to anyone

I bought the Pertronix D7134600 igniter III “stock look” distributor several months ago. It’s a really good looking distributor, if you’re not into things that are excessively flashy, and it appear(ed) well-made...

I’m actually a little bit miffed with Pertronix over this. I’ve used them for years, and I had a high opinion of their products. Considering that the problems I was having could have very well cost me my brand new motor, I’m upset that they were so dismissive of my issue.

Because I have a moderate camshaft, I set “total timing” on my motor at 36° @ 3,500 rpm. The distributor is supposed to have 21° (crankshaft) of mechanical advance all in by about 3,000 rpm, which would have put my initial at about 15°. I was having some drivability issues, and when I threw the light back on it I was shocked to see only 6° initial. Then I revved the engine up to 3,500 rpm to find it was still right on the money at 36°. Digging in further, I found that the distributor didn’t start advancing until after 2,000 rpm, and it kept on going all the way up to 34° of crankshaft advance @ 4,5000 rpm (40° total). All measurements were made with the vacuum advance disconnected.

When I called the Pertronix tech line, they told me, basically, that I was wrong. They said that it was physically impossible for their distributor to advance that far. They said that their Multi-Spark feature on the Ignitor III module could make a timing light read off by as far as 14°, and that I should just set initial timing by ear, and not worry about it.

THEIR ADVICE would have 100% led to ENGINE FAILURE!!!

I backed up my readings with an old “dumb” timing light (non-digital, no dial back feature), which confirmed what I was seeing. Luckily I purchased the distributor from Summit, so they let me return it in exchange for another unit. Just because I’m stubborn, I bought another Pertronix Ignitor III distributor, but this time I went with the billet series, which has an adjustable advance curve.

On the bench I installed springs and limiters which would limit total advance to 20° (crankshaft) and start the advance curve around 1,000 rpm, having it all in by 3,000 rpm. I set initial timing at 16°, and slowly confirmed the timing curve. It read EXACTLY as it should have, 16° initial, starting to advance at about 1,100 rpm, until it hit 36° at 3,000 rpm, and then stayed their as I continued revving the motor another 1,000 rpm to be sure.

There’s nothing wrong with my tools or my methods. But there was definitely something wrong with my Pertronix D7134600 ”stock-look” distributor. I wish I could have disassembled the distributor to see what was going on, but I was still under warranty, and didn’t want to be out the $200-something if I couldn’t fix it.

If you have a D7134600 distributor, please check your timing curve carefully. 34° of mechanical advance plus, say 16° of initial (50°), plus a variable amount of vacuum kicking in a part throttle cruising (60°+ total advance possible under some situations), could be catastrophic for your engine. And since faulty parts and/or bad assembly procedures usually occur in batches, it’s probably best to trust but verify in this instance.

Good Luck!

Casey
 

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That distributor is supposed to have 21 degrees of mechanical advance, all in by 3400rpm. You can gain/reduce vacuum advance with an allen wrench in the canister. I full turn = 2 deg
Pertronix III.png
 

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duplicate
 

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Discussion Starter #4
That distributor is supposed to have 21 degrees of mechanical advance, all in by 3400rpm. You can gain/reduce vacuum advance with an allen wrench in the canister. I full turn = 2 deg View attachment 743414
Oh, where did you find that? I just edited my post. Something’s funky. It’s advancing all the way to 4,500 rpm now...I’m showing 34° of total advance (vacuum advance is disconnected).
 

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I have the same distributor. The info is on the pertronix website under FAQS
 
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I bought the Pertronix D7134600 igniter III “stock look” distributor several months ago. It’s a really good looking distributor, if you’re not into things that are excessively flashy, and it appears well-made...

Never mind. Either it’s broken or my timing light just gave up the ghost. Now at 8° initial I’m getting 42° total @ 4,500 rpm. I’m leaning towards the distributor being broken because it doesn’t start advancing until about 2,000 rpm and keeps on going well past 4,000 rpm.
Sounds as though it is badly adjusted. Of course, I've never seen a new, used, or rebuilt distributor that was in spec, but no advance until 2000 rpm is pretty bad. Distributors, of all kinds, can be adjusted, even the vacuum-only Load-O-Matic.
 

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Discussion Starter #7
Sounds as though it is badly adjusted. Of course, I've never seen a new, used, or rebuilt distributor that was in spec, but no advance until 2000 rpm is pretty bad. Distributors, of all kinds, can be adjusted, even the vacuum-only Load-O-Matic.
I haven’t delved too far in because it’s new and under warranty, but it also looks like the module is held in place with some kind of melted plastic rivet, so that it is not independently serviceable without some minor re-engineering. I emailed them a month ago about a recurve kit, anticipating that I was going to need to mess with it, and they never responded. I guess I should have asked these questions BEFORE I gave them my money...
 

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For what it's worth, I had a Pertronix III RTR distributor about 6 years ago and it lasted for exactly 5 miles... at which point it started misfiring badly until I was only running on 2 cylinders (which was comical). Yanked it out and put a stock one back in and it was fine. Sent the fancy Petronix distributor back, put in the old distributor with a Pertronix I unit, which at least is small enough to keep a spare in the glove box in case it's needed.

This may all be anecdotal and it did happen a while ago so they may have improved upon the quality since then... but I stay away from those distributors even though they DO look really nice.
 
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Discussion Starter #9
Ok, so, the plot thickens. Guy at Pertronix said that most likely the multi-spark function of the distributor is what’s causing my timing light to read so high. He said that my 6° initial setting is probably right, and that the motor would then have 27° all-in at 3,000 rpm, because that’s all the distributor can physically do, and the phenomenon of what I’m seeing with it advancing all the way to 40° at 4,500 is just my distributor freaking out because of the multi-spark...

Does that sound right?
 

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Sounds possible, odd that it's so stable in your readings. Maybe try another timing light?

I can tell you that my very expensive digital tach / advance timing light from Snap On is absolutely useless when hooked to an MSD equipped car. I have to get out the ancient "dumb" Craftsman light if I'm just setting base timing. If I want to use the Snap On unit, I have to run it off a cheater box that I made from a GM HEI module.
 
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Discussion Starter #11
Sounds possible, odd that it's so stable in your readings. Maybe try another timing light?

I can tell you that my very expensive digital tach / advance timing light from Snap On is absolutely useless when hooked to an MSD equipped car. I have to get out the ancient "dumb" Craftsman light if I'm just setting base timing. If I want to use the Snap On unit, I have to run it off a cheater box that I made from a GM HEI module.
So, I’ve been reading a ton of posts about timing lights and multi-spark ignitions. I can never tell what’s conjecture and what’s not, on the internet, but the consensus seems to be that the “incompatibility” is all in the dial back feature, and if you just set your light on “0”, any timing light will work. Well, luckily I run a degreed balancer, and so I did that, and I am getting the EXACT same results (8° initial, no advance until 2,000 rpm, a hair above the 40° mark @ 4,500 rpm).

Summit’s not only willing to accept the return, but they said I could exchange it for any distributor I want (aren’t they amazing!?), so long as I pay the difference. That said, I sure would hate to take them up on this generous offer and have the issue end up being owed to operator error. Short of buying a really expensive MSD brand timing light, I’m all out of ideas though.

Anybody have thoughts?
 

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It's been a while since I messed with them, but why can't you bypass the MSD box to check/set your timing, then hook it back up when you're done ?

Edit: I didn't realize the Ignitor III is an MS ignition !
 

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Ok, so, the plot thickens. Guy at Pertronix said that most likely the multi-spark function of the distributor is what’s causing my timing light to read so high. He said that my 6° initial setting is probably right, and that the motor would then have 27° all-in at 3,000 rpm, because that’s all the distributor can physically do, and the phenomenon of what I’m seeing with it advancing all the way to 40° at 4,500 is just my distributor freaking out because of the multi-spark...

Does that sound right?
Guessing you already got the answer, but for confirmation, the Ignitor III has multi spark and this can throw some timing lights off. It does mine. The ancient "dumb" Craftsman light, as mentioned is one of the ones that handles the multi spark of the PIII.
 

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It's been a while since I messed with them, but why can't you bypass the MSD box to check/set your timing, then hook it back up when you're done ?
This is not an external MSD box, but an electronic component that replaces the points. You could put the points back in if its the stock style distributor with the stock advance plate, but I do not know if that can be done with the Pertronix Distributor.
 

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Discussion Starter #15 (Edited)
Guessing you already got the answer, but for confirmation, the Ignitor III has multi spark and this can throw some timing lights off. It does mine. The ancient "dumb" Craftsman light, as mentioned is one of the ones that handles the multi spark of the PIII.
Right, but here’s what I’m struggling with. I’ve heard a lot of folks say that they’re “thrown off” by strobing inconsistently or “fluttering”. The fact that I’m rock steady at 8° and it doesn’t move all the way up to 2,000 RPM when the timing is supposedly advancing doesn’t seem “correct”. Neither does it seem “correct” that the timing stops advancing at 3,000-3,500 rpm, but I can observe it continuing to advance all the way to 4,500. I mean, if it was as simple as walking down to Sears and buying a new timing light, I’d do that, but...

Does your light behave as oddly, or are the readings just off?
 

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Right, but here’s what I’m struggling with. I’ve heard a lot of folks say that they’re “thrown off” by strobing inconsistently or “fluttering”. The fact that I’m rock steady at 8° and it doesn’t move all the way up to 2,000 RPM when the timing is supposedly advancing doesn’t seem “correct”. Neither does it seem “correct” that the timing stops advancing at 3,000-3,500 rpm, but I can observe it continuing to advance all the way to 4,500. I mean, if it was as simple as walking down to Sears and buying a new timing light, I’d do that, but...

Does your light behave as oddly, or are the readings just off?
Mine bounces around a good 6 degrees, so its hard to see exactly where its at. But I can see the advance when it happens, just not exactly how much. I have a friend with one of those old Craftsman lights that keeps promising to bring it over, but that has not happened yet. So I advance it till it pings or is hard to start, and then back it off.
 

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Discussion Starter #19
I have an INOVA Digital Timing Light with advance and RPM reading that I use on My Pertonix III module and don't have any problems.
That’s what I have and it seems to work correctly as well. Interestingly enough, however, Inova says that their lights are NOT compatible with Multi-Spark ignitions

Mine bounces around a good 6 degrees, so its hard to see exactly where its at. But I can see the advance when it happens, just not exactly how much. I have a friend with one of those old Craftsman lights that keeps promising to bring it over, but that has not happened yet. So I advance it till it pings or is hard to start, and then back it off.
Interesting. Mine is dead on...
 

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Discussion Starter #20
So I found a neighbor with an old KAL Equip #904 Timing Light (non-digital) with an adjustment dial on the back, and, with the knob set at zero, I get the EXACT same results as my Inova digital light.

I don’t think there’s ANY way that two different timing lights, one digital and one solid-state, would read the exact same wrong timing curve, if the distributor was not the culprit.
 
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