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TR6 Pertronix ignition

brick7

Freshman Member
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Hey guys..Thinking about installing a Pertronix pick up module in my 72 TR6..Any advice on timing, spark plug gap or any other advise pertinent to the product would be greatly appriciated...
 

poolboy

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Don't put the ignition key in the ON position unless it's when the engine is running.
If you need it ON to do some electrical troubleshooting or whatever, pull at least one of the Pertronix wires off of the coil.
 
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brick7

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Thanks for your input..I knew about the ignition on warning from looking at the installation instructions on line...I run a puller auxiliary fan that is wired to operate in the relay override mode with the switch in the on position without the car running.. I will need to rewire to a direct power source..On one blog someone said to increase the plug gap and adjust timing.. I would also replace the coil with a high performance coil
 

dklawson

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If you choose to leave your plug gap alone, your standard coil will be fine. You only get more out of a "hot" coil if you also widen the plug gap. Start with the standard gap. Once you have a feel for how the engine is running, then open the gap in small increments. I have friends who run gaps close to .040" but they made that change over time, not immediately after installing the Pertronix. To support a .040" gap you will want a high performance coil. Making the gap increase in small steps will tell you at what setting you start to need the high performance coil.

You can also experiment with the timing. Do not assume your timing will be correct after installing the Pertronix module. If you buy the original Pertronix (not Pertronix 2 or 3), you can static time the engine just like you would with points. Once running check the dynamic timing. If you really want to get the most out of your timing, use an advance type timing light. Bring the engine to 4k RPM using the idle screws, then set the advance to about 32 BTDC. Return the idle speed to normal and test drive the car. Accelerate up hill in too high a gear. Listen for pinging and knocking. If any is heard, retard the timing in 2 degree steps until no bad noises are heard on your test drives.

I do not understand what you are saying about your fan and its relationship to the Pertronix.

When wiring the Pertronix, if your car has a ballast ignition system, do not connect the Pertronix RED wire to coil (+). On a ballast ignition car coil (+) will not be at 12V with the engine running. Instead, connect the Pertronix RED wire to any of the dark green wiring circuits on the car. Those circuits are fused, switched 12V and will supply the proper power to the ignition module at all times. If you buy a high performance coil for your car, it will likely be a full 12V coil. That will dictate wiring changes to the coil to eliminate the ballast resistor. That can be discussed at a later date when/if you decide to make additional changes.
 

poolboy

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A 72 should not have a ballasted ignition. That being the case you'll be OK just connecting the red Pertronix Ignitor wire directly to the positive terminal of which ever 3.0 ohm coil you choose.
As Doug said, after the Pertronix installation you will likely have to rotate the distributor a bit to get back to the ignition timing as it existed when you had points installed...Mine required a bit of a clockwise rotation...YMMV.
 

dklawson

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A 72 should not have a ballasted ignition.

You are correct. My mistake. I assumed a '72 TR6 would have the same ignition wiring as my '72 Spitfire. According to the Advance Auto Wire schematics it appears ballast ignition was not introduced on the TR6 until '73.
 

Sarastro

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My only recommendation is to choose the Pertronix only after you have reviewed the alternatives and still think it best meets your needs. People seem to think the Pertronix is the only option for an electronic ignition, and that's not the case--there are quite a few good units out there. I have always liked the Crane XR700. (I think it's being sold now under a different brand name, as Crane went bankrupt a few years ago.)
 

Tybalt

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In addition to disconnecting the Pertronix unit if you plan on having the ignition switched on for a while without the car running, I would also recommend disconnecting it if there is going to be any type of arc welding performed on the car as well. Same thing if you an multi-spark box such as those from MSD.

As for the Pertronix vs the Crane units, to me it's just a difference in means of getting to the same end point, getting a spark to ignite the fuel air mix in the cylinder. The Pertronix is a Hall effect electronic ignition very similar to the Lucas Opus ignition system in triggering but a separate amplifier is not employed like on the Lucas system. The Crane system is an optical based system with a light source, a light sensor and a chopper wheel as the triggering mechanism and does use an external amplifier box. Pick your favorite approach, then pay your money and take your chances.
 

poolboy

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As far as personal favorite, if that's where we're headed.....Points and condenser.
 

Sarastro

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Well, I think there is more difference than just the type of sensor. I'm not sure the Pertronix is even a real, capacitive-discharge ignition. The literature talks about how it handles dwell, for example, and in a real CD ignition, dwell is just irrelevant. If it's just a points-replacement circuit, dwell still would matter. Also, the Pertronix seems to use four separate magnets for the triggering the spark, which makes accurate timing unlikely. Most magnetic-sensor ignitions use a thing called a reluctor, which avoids that problem.

I put an oscilloscope on a Crane at one point, and was pleased to see that it generates multiple sparks; I doubt that the Pertronix does that--there is a limit to the degree of functionality you can fit into a small package.

As for preferences, the superiority of a CD ignition is so overwhelming, I can't see much reason to use points and a capacitor any more. Some people are concerned about the reliability of the electronics, but the CD is in fact much more reliable than points. Often people say that points are really more reliable, because you can replace them if there is a problem. That argument works until you have to replace them at night, in the rain, in 35-degree weather, and your numb fingers drop a screw into the distributor. And of course, if you are really worried, you can carry a spare ignition module.
 

dklawson

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Steve, I don't remember anyone I know saying that points were more reliable. The argument I remember is your own comments but made in a minor key... "You can fix points on the side of the road, in the dark, in a freezing, pouring rain". Yes, if you carry a spare ignition module you can swap that along the road as well. However, it is more financially appealing to carry a set of points and a condenser as spares than a relatively expensive spare module. The nice thing about Pertronix is if carry a spare set of points and a condenser, you can install those in place of the Pertronix module should it fail.

I have never looked at CD ignitions so I cannot comment on those. However, I don't understand your comment about dwell not being important. As you said, the Pertronix is basically an electronic switch used in place of points. The important argument there is that it gets away from mechanical components that burn and wear out. The dwell is different when you install a Pertronix and it is my understanding that that change allows for better charging of the coil than is possible with the mechanically limited points. Is it optimized for super performance? Probably not. However, it does allow for opening up the plug gap and justifies the use of performance coils. I defer to your understanding but this is what was explained to me.

I do not dispute the merits of the Crane ignition either. I had one installed in our GT6 for about a decade. It worked well. However, we had to replace our Crane/Alison ignition when the potting for the remote amplifier failed. Water got inside during an engine wash. This may simply have been my bad luck. We installed a Pertronix as a replacement for the Crane and I have not given it much thought since.
 

Tybalt

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It is correct that the Pertronix is not a capacitive discharge system, it is an induction system. Like the Pertronix, the Crane XR700 and XR3000 are also inductive systems. The differences are that the Pertronix is Hall Effect based system without an external box needed while the Crane is an optically based system with a required external box. The difference between the two Crane models is that one requires ballast resistance while the other has a chip to control the ignition coil current and dwell and must be used without ballast resistance as a result.

To get into true capacitive discharge mode with these triggering systems, you need to add a capacitive discharge ignition box such as something from the MSD 6A family or the Crane HI-6 family. There are other CD boxes out there from additional sources as well as other models out there from these sources, but for the most part, the "something or another 6 something" boxes are going to be what you see in most older street cars (like our old crocks) that have had aftermarket CDI systems added.
 
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