Wacky Tach

[a7dz]

E;

I also have one stuck at 1100. That you can use as well. I believe I have a good one to replace it.

[Marty Rogan]

Here's an update on this problem.

I got a known good replacement tach off EBay and installed it over the weekend. It had the same problem. At this point, I began re-looking at the Pertronix.

The optical sensor in the distributor was looking dirty, so I pulled it off to clean it. Three of the magenets came loose from their slots. I happened to have a spare, so I cleaned that up and installed it. Now the tach will spin smoothly up to 6K with no problems.

So if anyone experieinces the same problems, I would recommend cleaning the optical sensor and checking that the magnets are in place.

Marty

[MikeW]

Three of the magenets came loose from their slots. I happened to have a spare, so I cleaned that up and installed it.

As I recall when installing my Pertronix there's a piece of green tape holding the magnets in place and you're not supposed to remove it even though it looks temporary.

[Marty Rogan]

As I recall when installing my Pertronix there's a piece of green tape holding the magnets in place and you're not supposed to remove it even though it looks temporary.

Yep, green tape is still in place. The magnets fell out underneath the tape. The older design optical trigger had a plastic ring at the bottom to hold everything in. I don't understand why they changed to an inferior design, when what they had seemed to work fine. I suppose they save ten cents per 100 units in thier manufacturing costs.

Marty

[240ZX]

Just curious Marty......if there are magnets in your distributor then what would be the purpose of an optic sensor? IIRC, aren't the Pertronics units magnetic triggering devices?

Tom

[Arne]

Hmm.... I wonder about the health of my yellow car's ZX ignition now. There have been a couple of times that I felt the ignition was acting a bit funky, and the tach is intermittently bad. Might be worth swapping the points dizzy back on for a test...

[Marty Rogan]

Just curious Marty......if there are magnets in your distributor then what would be the purpose of an optic sensor? IIRC, aren't the Pertronics units magnetic triggering devices?

Tom

The Pertronix optical sensor is basically a plastic ring that is installed over the distributor post (under the rotor). That contains 6 small magnets, equally spaced. This ring is then warpped with the green tape mentioned above. I wish I had a picture of it, but I don't. The distributor does not have magnets in it. The only magnets are the ones in the Pertronix optical trigger. It basically acts as an on/off switch as it rotates inside the distributor.

I think the term "optic sensor" is a misnomer (SP?). The sensor "sees" the magnet as it passes by. It does not "visually see anything. It just senses the presence of the magnets.

Arne, I would do some thorough cleaning inside the dizzy and see if it helps. the swap would tell you a lot too.

I keep going back and forth as to which electronic ignition set up is the best for these cars. So far I have not seen or heard of a clear winner.

Marty

[MikeW]

I think the term "optic sensor" is a misnomer (SP?). The sensor "sees" the magnet as it passes by. It does not "visually see anything. It just senses the presence of the magnets.

I agree that the term is causing confusion here. There really are some systems that use "optical" sensors (a beam of light passing through a disk with holes in it). In fact, computer mice used this technology back when they had a rolling ball. Most mice these days have no moving parts.

[Arne]

Arne, I would do some thorough cleaning inside the dizzy and see if it helps. the swap would tell you a lot too.

I keep going back and forth as to which electronic ignition set up is the best for these cars. So far I have not seen or heard of a clear winner.

Marty

I do like the stability (set-it-and-forget-it) and hot spark of the electronic ignition. But I don't like the seeming lack of reliability of most of them. I keep hearing of odd issues with Pertronix now and then, and the ZX ignition ignitor-boxess seem to be prone to sudden failures - not too surprising, I guess, considering their age and all. But disconcerting in that when one of those units dies, it just flat dies. Nothing you can do on the roadside unless you happen to carry a spare ignitor unit.

On the other hand - for cars like mine which are mostly stock, a points ignition still does the job. Sure, I'll have to replace them once in a while, and set the gap and dwell angle, etc., etc. But I can carry a spare set of points with me in the car pretty easily, and they seldom fail without warning anyway. I'm strongly thinking of staying with the points in my new red car.

[MikeW]

Nothing you can do on the roadside unless you happen to carry a spare ignitor unit.

On the other hand - for cars like mine which are mostly stock, a points ignition still does the job. Sure, I'll have to replace them once in a while, and set the gap and dwell angle, etc., etc. But I can carry a spare set of points with me in the car pretty easily, and they seldom fail without warning anyway. I'm strongly thinking of staying with the points in my new red car.

You can easily carry a spare set of points with the Pertronix as well. It's very easy to switch back to them as the Pertronix merely replaces the points and nothing more.

[yor5150]

I rarely, if ever pitch anything from these old cars. In fact I am collecting the original parts that I am missing (steel fan, steering wheel, etc.) to put it back original once it is retired from track duty. Maybe we could work something out though. I would be glad to loan it to you to support the cause, if you send it back repaired some day. How does that sound to you? In the short term, I just need a tach that works!

Marty

I found a 240Z at a local junkyard. It was a '72 but someone had stashed some parts in the hatch area, one of which was a long pig tailed fuse block with I believe to be a 25410-E4600 Assy Fuse Block that fits "Up-To" 12/70. I also saw a steel fan and remembered reading something about the earlier 240's having them but I was so busy pulling parts from the '72 that I didn't grab it. If you have a pic or two please post and if it is indeed a steel fan from a Z I'll snag it for you if you want it. It's yours for whatever it costs: junkyard price + shipping costs.

Cheers

[Marty Rogan]

I found a 240Z at a local junkyard. It was a '72 but someone had stashed some parts in the hatch area, one of which was a long pig tailed fuse block with I believe to be a 25410-E4600 Assy Fuse Block that fits "Up-To" 12/70. I also saw a steel fan and remembered reading something about the earlier 240's having them but I was so busy pulling parts from the '72 that I didn't grab it. If you have a pic or two please post and if it is indeed a steel fan from a Z I'll snag it for you if you want it. It's yours for whatever it costs: junkyard price + shipping costs.

Cheers

Thanks for thinking about me. Beandip actually located a steel fan and a steering wheel for me a while ago. I still need the parts that are installed under the horn though. If that long pigtailed fuse block is not melted down or broken, I might be interested in that. Send me a PM if you want to sell it.

Thanks,

Marty