Hi everyone, hoping someone can help me diagnose this issue. My 1971 240z has the Pertronix 1761 ignitor installed - recently I realized I’ve still been running the stock spec coil (with resistor) and should be using the recommended Pertronix coil, so I installed that - it is the 3ohm version (part # 40511).

I removed the ballast resistor since it’s the 3 ohm coil - I connected the wires from the resistor together with a jumper (the green/white wire and the black/white wire were connected to the resistor, and they’re now connected together with the Pertronix coil installed). The other wires are all connected correctly to the positive and negative side of the coil.

The car idles a little higher with the new coil, but overall idles smoother and runs better, except when it hits about 4k rpm. Once you hit 4k rpm, the car starts hesitating/lunging back and forth and loses a lot of power. I’ve tried advancing the timing by a few degrees but it didn’t help. The car’s idling a little too high (around 1,100 rpm), and advancing the timing moved the idle up.

I was running the BPR6ES plugs (I believe 0.035 gap) . I just tried a set of BPR6ES-11 (has a 0.044 gap) thinking that may help - it runs slightly better with the higher gap but still runs into the same issue at 4k rpm.

I’m wondering if anyone knows what would be the most likely culprit of this issue. Is it most likely a combination of timing adjustment and idle adjustment, or something else?

1 hour ago, lm71z said:

recently I realized I’ve still been running the stock spec coil (with resistor) and should be using the recommended Pertronix coil, so I installed that - it is the 3ohm version (part # 40511).

1 hour ago, lm71z said:

The car idles a little higher with the new coil, but overall idles smoother and runs better, except when it hits about 4k rpm. Once you hit 4k rpm, the car starts hesitating/lunging back and forth and loses a lot of power.

How did it run with the old coil and ballast resistor? Over 4,000 RPM.

4 minutes ago, Zed Head said:

How did it run with the old coil and ballast resistor? Over 4,000 RPM.

It ran fine and didn’t have that symptom over 4000 RPM, but was lacking in power

7 minutes ago, lm71z said:

It ran fine and didn’t have that symptom over 4000 RPM, but was lacking in power

Edited -

Are you saying that it ran the same, except for the lunging? Trying to figure out if you're trying to solve an old problem or a new one.

Seems like you might be saying that you tried to solve the over-4,000 RPM problem by switching to a 3 ohm coil but nothing changed much. You have a lack of power over 4,000 RPM. Might be that the ignition system is not the problem.

Edited December 28, 2025Dec 28 by Zed Head

3 minutes ago, Zed Head said:

Edited -

Are you saying that it ran the same, except for the lunging? Trying to figure out if you're trying to solve an old problem or a new one.

Seems like you might be saying that you tried to solve the over-4,000 RPM problem by switching to a 3 ohm coil but nothing changed much. You have a lack of power over 4,000 RPM. Might be that the ignition system is not the problem.

Definitely a new problem. I meant the car was overrall down on power with the old coil + resistor, but had no lunging/hesitation and went over 4k without a problem. The reason I upgraded to the Pertronix coil is because I read its recommended to run the Pertronix flamethrower if you’re using the Pertronix 1761 ignitor system for the coil, but now this has created a new problem. So, with this new coil, there’s a little more power and responsiveness, but I now hit a wall at 4k where the car lunges and hesitates, basically loses power past that rev point.

Edited December 28, 2025Dec 28 by lm71z

If it was mine I'd put the old parts back on and see if the new problem goes away. Those electronic ignition modules are sensitive. Might be damaged or it might not not really like the 3 ohm coil. Have to put the old parts back on to be sure. Good luck.

In my experience, not working over 4 or 5k is a standard feature of the pertronix igniter.

These sherryberg distributors are said to work ok.

https://www.aliexpress.com/item/1005006104687656.html

Edited December 29, 2025Dec 29 by jonbill

I checked the link. They don't even show what's under the cap. How do you know it's not the same module? I think that Pertronix parts are made in China now.

It's really surprising how the world as a whole (no offense intended) has become so much more okay with buying Chinese knockoffs. Products made in China by reputable brands are different, I think, than "copies" of reputable products. I have to imagine that if the product fails you're out all of the money. Probably no return policy or warranty.

Copied the link again, it should be clickable.

https://www.aliexpress.us/item/3256805918372904.html?gatewayAdapt=glo2usa4itemAdapt

Here is the "Seller info" from the link in the ad, for Sherryberg. Weird stuff! Looks like a whole enterprise based on copying auto parts.

Sure, there's lots of potential downsides with buying from aliexpress, although Sherryberg are quite a well known brand, even though you've not heard of it.

The internet is full of reports of Pertronix being junk, and that's been my experience too. Conversely I know a couple of people who have the Sherryberg distributor and are very happy.

This is not rocket science - I find it more surprising that a long standing US brand manages to make a product that fails so often, than that a cheap chinese brand manages to make one that works reliably.

On 12/27/2025 at 6:23 PM, lm71z said:

Hi everyone, hoping someone can help me diagnose this issue. My 1971 240z has the Pertronix 1761 ignitor installed - recently I realized I’ve still been running the stock spec coil (with resistor) and should be using the recommended Pertronix coil, so I installed that - it is the 3ohm version (part # 40511).

I removed the ballast resistor since it’s the 3 ohm coil - I connected the wires from the resistor together with a jumper (the green/white wire and the black/white wire were connected to the resistor, and they’re now connected together with the Pertronix coil installed). The other wires are all connected correctly to the positive and negative side of the coil.

The car idles a little higher with the new coil, but overall idles smoother and runs better, except when it hits about 4k rpm. Once you hit 4k rpm, the car starts hesitating/lunging back and forth and loses a lot of power. I’ve tried advancing the timing by a few degrees but it didn’t help. The car’s idling a little too high (around 1,100 rpm), and advancing the timing moved the idle up.

I was running the BPR6ES plugs (I believe 0.035 gap) . I just tried a set of BPR6ES-11 (has a 0.044 gap) thinking that may help - it runs slightly better with the higher gap but still runs into the same issue at 4k rpm.

I’m wondering if anyone knows what would be the most likely culprit of this issue. Is it most likely a combination of timing adjustment and idle adjustment, or something else?

When it doesn't want to rev past 4000 rpms, is that under a load? Will it rev past 4000 rpms with the trans in neutral or with the clutch disengaged?

I would guess that the quality of the parts is similar. They're both made at the same type of place, most likely. It's kind of weird isn't it, that the business would create an aliexpress persona using the name of what appears to be a non-Asian woman. Why not just use the business name? Seems deceptive. Or just, as I said, weird stuff!

jonbill, you're in Australia aren't you? You might have more familiarity with aliexpress since it's probably easier and cheaper to get parts from them than eBay. Due to the proximity to the Asian suppliers. Just guessing, don't know..

I'm still interested in what's under the cap. I'll dig around and see if I can find something.

I think I might have found it. Seems unique, never seen anything like it.

https://www.aliexpress.us/item/3256808424004821.html