Pertronix Distributor

[Yadkin]

As said earlier, I merely get the basic jist. I can see why the circuit would oscillate (wikipedia has a "gif" demonstrating its operation) but how does it filter? I'm guessing that it stores the peaks and uses that to fill in the valleys.

I plan on reading the manufacturer's instructions when I get the unit and following them to the letter.

The same manufacturer makes 10 and 25 amp units. I was thinking of using the 25 and just using it to filter the ignition two fat wires to the ignition box, but for an extra few bucks I can filter the entire alternator output.

What I should have done (or still can do) is unplug the alternator from the circuit and see if that improves my scope readings.

[Yadkin]

I installed the filter but it's snowing and they salted the roads here so no test drive. I've attached a picture of the install plus an interesting scope graph.

The filter is behind the battery. I have an 18" long cable (max length allowed by the filter manufacturer) from the alternator to the filter. On the BAT side I have a battery cable, my starter hot lead, a cable to my 100 amp main breaker and then the ignition box hot lead.

Channel 1 is the alternator output. Ch 2 is the battery positive terminal. This is at idle with no accessories running. Big difference between the two.

Channel 3 is my coil secondary. The CAO dial on the ignition box is set to 2, which creates a second spark at 4 crankshaft degrees after the initial. Pertronix recommends that as your initial setting and go up or down from there.

Channel 4 is my #8 spark plug wire. It's a lot more consistent than it was before. This points to a solution, but I won't be able to tell for a few months until spring and we have a few good rains to wash the salt off.

[Yadkin]

A question for you Dave. A while back you advised me to put a fuse between my alternator and battery. By installing this filter I've bypassed my main 100 amp breaker that I had been using for that. My new wiring diagram is below.

I need to keep the #6 cable from the alternator to the filter 18" long or less. In order to fuse this, I was thinking of building a fusible link, a short length of #10 within that connection. So the first 4" or so of my 18" long cable, connected to the alternator, would be a #10 wire. Do you think this will be an acceptable solution?

[Yadkin]

Decided to mount an AMG type 100 amp fuse block between the alternator and filter. On order from Amazon. I spent an extra ten bucks and bought a fuse holder by Blue Sea Systems. It looks a lot more attractive then the cheap plastic units sold by Bussman or Littlefuse.

[simplyconnected]

Steve, I didn't see your post yesterday.
I think you are missing the main goal here. The purpose of the fuse is to protect against a faulty alternator resulting in a burned wire and possibly a fire. Alternators use solid state components that can go bad at any time, especially when nobody is around.

If a diode or SCR shorts, it will draw as much current to ground as your battery will supply, as fast as possible.

If you place the fuse between your battery and alternator, when this happens, the fuse will blow and your alternator will be isolated BUT your car should still start and run off the battery.

So... the first order is to fuse the alternator. Any wiring after the fuse should not interrupt power from the battery to the starter solenoid (and ignition circuit). It's like a tee, or a parallel branch.

This was and still is my suggestion:

...I can understand putting a capacitor somewhere around your engine but not by the battery...

This is because the source of your noise is your alternator and ignition circuit, both of which are mounted to your engine. Batteries never produce noise. Questions?

[Yadkin]

Dave, here's my revised wiring diagram.

We're deep into winter up here so a test drive isn't possible for a while. But based on the new scope readings and the fact that the engine starts up easier I think the combination of the All Petronix ignition with this alternator filter have solved this pesky little problem.

[Yadkin]

Picture of the filter.

[simplyconnected]

Yeah, that center ground lug is important. THAT is your capacitor. The huge posts have an inductor coil between them, inside. So, connect the center ground lug to your alternator case, not your battery.

You show a 'starter' with two wires. Is this a GM starter motor or one with a separate solenoid?

Finally, I see a 100-amp breaker. Is it self-resetting?
If your ignition wires go through the self-resetting breaker, get them off. If that breaker opens your engine will stop. It's one thing to protect the fuse box and all associated branch circuits BUT keep your ignition circuit by itself, as Ford did. - Dave

[Yadkin]

Right now the filter is grounded with a #6 to a common bolt (to the chassis) with the alternator ground and main engine ground. The car is at my cabin, so I'm going by recollection now, but I think the alternator ground is a #10. I'll check that, as it may explain the less than smooth scope readings while the alternator is under load (32 amp cooling fan). If so, good catch.

The starter is a performance type with a separate #10 wire that triggers an integral solenoid. There is no longer a Ford type solenoid mounted on the chassis. I did this on purpose to make the car harder to steal.

The 100 amp breaker is not self-resetting. The OE ignition circuit is powered by this breaker and I intend to keep it that way. I use that as a battery cut-off along with the ground connector on the battery. I can trigger that and the tell-tale isn't obvious, another theft preventative.

Right now both my EFI and ignition box main power and ground are direct to the battery, un-fused, or engine grounds, as required by the manufacturers. The reason that I was given is that the battery is the filter. Apparently that didn't work so well. If the car runs well with this filter I'd like to move those wires into my main power panel with their own fuses.

[simplyconnected]

...The 100 amp breaker is not self-resetting. The OE ignition circuit is powered by this breaker and I intend to keep it that way...

Suit yourself. I gave my suggestion but it's your car.

Most cars do use the battery as a filter with no ill affects and never a second thought.

If you want real theft protection, shut off your FUEL. Thieves will have electrical knowledge but they will not plumb because that takes far too long. - Dave

[Yadkin]

Tweaked it a bit over the weekend. The instructions for the filter insisted that the ground strap to the alternator be a #6 less than 18" long. I went to several stores to find a #6 connector that had a screw hole small enough for my alternator ground connector. Hopefully this smooths out the engine over the entire RPM range.

The ground required by the alternator itself is only a #10. I still have that going to the chassis.

[Yadkin]

If you want real theft protection, shut off your FUEL. Thieves will have electrical knowledge but they will not plumb because that takes far too long. - Dave

Good idea, and all I have to do is take out one fuse in my trunk panel to cut off power to my fuel pump relay. But I think a thief with electrical knowledge will have a challenge here. Where my starter solenoid used to be is a 100amp circuit breaker. That feeds a custom electrical panel and they'll have to figure that out to jump start the car.

[Yadkin]

I think I found the last of several gremlins causing my rough running problem. I've marked the damper with a paint stripe not just at zero degrees but at every 90 degrees. This lets me use my timing light on each wire to verify correct timing for all eight cylinders. When I looked at plugs 7 and 8, I'd get random misses. I cleaned off most of the anti-seize from the plug threads and sealing surface, and the problem went away. I never used to use that stuff until lately, when several guys told me that I should. Even though I've never had a plug seize, even in an aluminum head, I used it anyway. It's supposed to be conductive.

[simplyconnected]

The TYPE of anti-seize you use makes a difference. In fairness, most people don't know that many types exist.

Mine is N-1000, made by Fel-Pro but it is copper and graphite-based and good up to 1,800 degrees F. It has a copper color, not an aluminum color and it is highly conductive. I use it on everything including wheel lug nuts and yes, spark plugs. It's also designed for stainless applications. I apply a very thin coat to spark plug threads, then I run them in and back out, then another very thin coat on top of the one I had. That ensures enough is spread over both male and female threads.

I've been using this on Edelbrock aluminum heads (and OEM cast iron) since 1990 and have never had a thread problem.

I see that Loctite 51147 is also a copper-based anti-seize but I have no experience with it. There is also a graphite-based anti-seize offered by Fel-Pro for electrical conductivity. - Dave

[Yadkin]

I've had a jar of the stuff for years, I think it's a Permatex product. I bought it for brake fasteners. Silver in color.