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g-mam, June 28, 2009 in Trucks
Single point dist ONLY.
I rebuild distributors for a living (its all I do), and if there's one thing I can say without any doubt in my mind, its that points will produce more power at the wheels than Pertronix, if the distributor is in good working order. Wear and tear reduce the distributor's ability to hold a steady dwell. Pertronix masks that. Pertronix is also susceptible to causing misfires by reading mild spark plug wire noise (ALL plug wires produce some level of noise.) That noise can be sensed by the module causing it to randomly fire, leaving the coil undercharged when the next plug fires. The level of undercharge varies, and you end up withe a loss of 4-7 hp on average as measured at the rear wheels versus using points.
40KV coils do not always produce that power level. If they did, they would overheat and fail. Most of the time our Datsun cars and trucks run on 12-15KV. We need a 3 Ohm coil, no external ballast resistor, no matter if we run points or Pertronix, or Crane, or whatever, with exceptions of high output systems like MSD and Pertronix II, which I do not recommend even if you are running at a competitive level. For instance, I'll be running points in my 620 running for a land speed record at Bonneville this August, yes running points at 8500 rpm! I'll test it at the dyno to confirm the 14.5::1 compression doesn't affect spark quality, but it should be fine as its a winning recipe I have concocted many, many times over the years.
I don't know about the Pertronix system but it, and the factory EI system's advantage of never having to mess with points maintenance ever again is worth it. I've driven an IEI set up until it wore out the cap button and failed to start. This was from complacency... never having a problem with it and totally forgetting to do even a rudimentary inspection of parts wear. Didn't even have the plugs out in 5 years it just ran so well.
There is a lot of 'built in' distributor slop from a design first used in the late 60s L engine. Later Z and KA 'distributors' (CAS actually) were splined to the drive spindle for more accuracy.
Personally, I'm not willing to give up 4-7 hp (average) by installing a Pertronix and getting "better reliability." In my book, that's detuning and I don't believe in that, just to avoid adjusting points every 6k miles? On a distributor that's not only front and center, its upright! It can't get any easier!
After testing MANY electronic ignitions on the chassis and engine dynos, the only time I saw a gain in power or any improvement in drivability was when a crank fired system was installed (no distributor at all). Even then, plug wires can cause issues if they're long enough and sensor wires aren't properly shielded. I'm changing out the crank sensor in my Willys truck right now to alleviate a signal quality issue.
Do you still use the vacuum advance with the first gen Pertronix?
Always use vacuum advance. It only comes into play at part throttle.
Agreed. It was suggested by another member to not use it because the Pertronix has a built in advance.
Pertronix does not have 'built in advance'.
Pertronix only gets rid of the points... does nothing for the spark as you have to use 3 ohm coil or 1.5 ohm coil and a 1.5 ohm ballast resister. No frigging way you get 40K volts from that. After market coil makers make all kinds of claims that are bullshit. Paint them red and give them names like 'Flamethrower'
I am using my stock coil. Works fine for me.
Me too but thinking of painting it red.
Not me....rattle can Mexican chrome.
OOoooo can I use that idea???
Sure....free country and open forum.
I wrapped my coil in the can of a preferred beverage.
FWIW I tried the Pertronix setup competitively for a season. I didn't dyno, but telemetry showed my final/top speed before breaking zones was consistently lower than previous years on all tracks in all weather. That would be consistent with what @distributorguy mentioned.
However, I did notice better throttle response when transitioning out of sharper corners. esp. going from light maintenance throttle to WOT. The engine just seemed to "fire better" in that first moment of mashing on the gas.
Those observations could obviously be due to a variety of other things (driver attitude?), other small things changed on the car as well throughout the season... But, thinking back a few years, I thought I'd give my seat-of-the-pants account.
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