Spitfire spitfire pertronix installation question

[Dan76spit]

hi all
i have a 76 spitfire with a mallory dual point dis. i am wanting to install a pertronix electronic ignition that installs in the dis i have a couple of questions. i have included some pics.

1- my dis has a vacuum advance and i cant use the pertronix with an vacuum advance so can i take off the advance? there is a linkage inside and another plate which causes me to not be able to install the pertronix. i have weber dgv carb.

2-my coil has three wires coming off of it... which one is positive and which is negative? the top wire in the picture goes to the starter solenoid over by the battery. i believe that one is positive? one side is marked 'cb' and the other is 'sw'. the top wire has no markings. (sorry seems like a stupid question but i cant fig out.)

3-the small barrel shaped item on the side of the dis, the condensor i believe, it has a wire hooked up to the points do i need to hook up that wire when i install the pertronix unit?.

4-do i have a ballasted ignition system.
any advice will surely help. thanks much guys.

 

[dklawson]

Good questions.

1) I have never installed a Pertronix in a Mallory dizzy but if you say you cannot fit the Pertronix because of interference I believe you. You do not have to have the vacuum advance. Vacuum advance is for economy during part-throttle cruising. Disconnect the advance hose at the dizzy and plug it with a small bolt or similar.

2)Old coils were marked "SW" for ignition SWitch and "CB" for Contact Breaker. They were first designed for positive ground cars so you cannot go strictly by the coil terminals to tell what is what... as it may be wrong.

First determine if your car is positive or negative ground by looking at the battery. If your car is positive ground, the coil SW terminal will be "hot" and connected to the ignition switch. If your car is negative ground, CB will be hot and connected to the ignition switch (or should be). The "other" coil terminal will be connected to the wire going to the dizzy regardless of ground.

Look again at that wire coming from the solenoid. If you have a solenoid with two (2) small spade lugs (not including the ones for all the brown wires) then you have a solenoid suitable for a ballast ignition system. One terminal will have the white/red wire on it. That wire comes from the ignition switch and energizes the solenoid when you turn the key. The second terminal (if present) will have a white/yellow wire on it. The OTHER end of that white yellow wire goes to coil (+)... the side of the coil connected to the ignition switch.

However, whether or not you still have a ballast ignition system depends on the resistance of the coil and whether or not someone could have changed it. Here are your quick tests:
Remove dizzy cap and place a coin between the points.
Switch on the ignition and use a multimeter to measure between the ignition switch side of the coil and ground. Record your value, turn off the ignition switch, remove the coin.
Now mark and remove the coil wires.
Use your multimeter to measure coil resistance.
Record your value in Ohms and refit the wires.
Post your measurements here and well tell you what you have.

3) The barrel is a condenser as you suspected. You do NOT need that with the Pertronix. Save it and the old points in the boot so if the Pertronix should ever fail you can convert the dizzy back to points and drive home.

4) For the ballast ignition system, make the measurements I listed in step 2 and report back what you find. From the values you observe we will be able to tell you the ignition system type.

 

[Dan76spit]

thanks
great so i can remove the vacuum advance and plug the line and disconnect the condenser.

so i have a negative ground so cb is the positive side and sw is the negative side, correct?

so i should unhook the top wire from the coil as i shouldn't need it with the pertronix, correct?

i've never had any experience with points so alot of this is new to me. thanks so far. im not even sure if it matters if i have a ballasted system with the pertronix kit as it only has two wires to hook up the coil.

thanks again

 

[TR3driver]

im not even sure if it matters if i have a ballasted system with the pertronix kit as it only has two wires to hook up the coil.

It does matter; if you keep the external ballast then the Pertronix wire does not connect to the coil.

 

[dklawson]

1) Yes you can disconnect the vacuum advance, just don't leave the tubing back to the carb open. Plug the tube.

2) With negative ground, CB goes to the ignition switch, SW goes to the point in the dizzy.

3) Top? Bottom? Sorry, even with a picture I would not like to answer that. I would not unhook ANYTHING from the coil if the engine works as is.

4) <span style="color: #CC0000"><span style="font-style: italic">Does a ballast coil matter with Pertronix?</span></span>
YES. You MUST know what type of ignition your car currently has to properly hook up a Pertronix unit. The module can operate a ballast coil IF the ballast resistor is left in place and IF you supply the module with power from a source OTHER than coil (+). The wiring is simple regardless of what type of ignition wiring your car has. However, get a multimeter and measure the voltage and coil resistance I mentioned earlier. Then we can tell you how to connect the Pertronix so you can use your existing wiring and coil.

 

[Dan76spit]

ok thanks very much guys. i will bring my multimeter home from work tomorrow and test the values you said.

 

[poolboy]

From the Pertronix box:

 

[dklawson]

The picture from Poolboy shows part of the story. The details are on page 2 of the Pertronix instructions in the link below.
https://www.pertronix.com/support/manuals/pdf/ignitor12vneg.pdf

Specifically, with ballast ignitions you connect the Pertronix red wire to a power source before the ballast resistor (you connect it to a full 12V source).

 

[Dan76spit]

ok coil resistance came up 3.8 ohms

the other with a coin between the points i get it on the sw side 17.7v and on the cb side i get 1.6v

thanks guys so much

 

[TR3driver]

the other with a coin between the points i get it on the sw side 17.7v and on the cb side i get 1.6v

If that is not a typo, then I think there might be something wrong with your voltmeter.

 

[Dan76spit]

ok i did with another volt meter and got sw 8.41 and cb 1.05 must be an issue with that meter cause i got a different reading with my other meter...

 

[Dono]

Pertronix.com has great support tech line. You may phone them, or email. They could offer some add'l info no doubt.

Thanx, Dono

 

[dklawson]

ok i did with another volt meter and got sw 8.41 and cb 1.05 must be an issue with that meter cause i got a different reading with my other meter...

Even those readings are a bit odd. There are also other wiring issues to resolve.

First, you said your car is NEGATIVE ground. Therefore, the wire going to the distributor should be on the coil SW terminal. The two "white" wires should be on the CB terminal. Once the wiring is changed, repeat your voltage measurements and confirm you get the same values. (The coils marked SW and CB are older and originally designed for positive ground cars. I do not think it is original to your car).

If you get the same 8.4V on the "high" terminal on the coil (CB after you move the wires) that implies you have wiring for a ballast ignition system. Since I did not see any "pink" wires on your coil... is there a ceramic brick mounted on or near the coil? This brick would be about 1/2" square and 2" long. It will have wires connected to it. That brick IS a ballast resistor.

The 3.8 Ohms you measured on the coil is a bit high but implies you have a standard coil, not a ballast coil.

Therefore, your car appears to have a standard coil but wiring for a ballast coil. The coil is also (apparently) wired backwards. This presents several problems for you. As it is now, your coil will be producing weak sparks (both because it is a standard coil with ballast wiring and because it appears to be wired backwards). The engine may be very hard to start and may misfire under load. Is that why you want to install a Pertronix?

If you install a Pertronix ignition you will need to choose how you want to operate the ignition system. If you want to retain the ballast ignition system you will need to get a ballast coil (1-2 Ohms) to replace the one you have. You will also need to power the Pertronix by connecting its “RED” wire to a switched 12V source and not connect it to the coil. If you decide to run either the coil you have OR a new standard coil you will need to bypass the ballast resistor.

Were I you, whichever you choose to pursue, I would get a new coil. If you go with the Pertronix option, consider buying one of their matching coils so you know the parts are compatible.

 

[TR3driver]

FWIW, I'm pretty sure the original ballast resistor for a 76 Spit is incorporated in the wiring harness (as resistor wire).

I agree with everything Doug said. In addition, that 1.05 across closed points seems pretty high to me. Won't matter if it's just burned points, but it might indicate a poor ground for the point plate, and the Pertronix uses the same ground path.

 

[Dan76spit]

ok i reversed the wiring on the coil and retook the readings they are essentially the same. 8.39 cb and 1.03 on the sw.

the car is def a neg ground as the neg wire off the battery goes to a exhaust manifold stud on the engine. that is were i used for the ground reading with the multimeter.

as far as a ballast above the coil there are three 'blocks' none of which are ceramic as far as i see. here is a pic.

the wire in my original pic that goes to the 'cb' does have two white wire attached together to that black wire. the top wire on the screw stud goes over to the solenoid

how would i rewire this set up with a regular two post coil?
how do i wire in the pertronix?

sorry for all the questions but you guys have been a ton of help so far. thanks again

 

[dklawson]

First, I would move the ground wire from a manifold stud to one of the bell housing bolts (after scraping away a bit of paint). Manifold studs are typically quite rusty and won't provide a good ground path over time. (FWIW, I run the ground wire to the bell housing, then I run a second ground wire from there over to a starter mounting bolt.) In your voltage measurements, don't measure on the exhaust stud itself but use the end of the cable... or the (-) terminal on the battery.

I'm sorry but the last picture you posted comes up only as a "red-X". Please try posting it again.

Randall, I'm not sure what they did on '76 Spits. On my '72 there is a traditional ballast resistor piggybacked on the coil. They did not use the white/pink ballast wire. Again... I'm not sure what would be on a '76.

You asked about how to go about changing the wiring to a "regular two post coil". You cannot reference coils by their number of terminals. You have to talk about them in terms of ballast, non-ballast (standard), or electronic ignition. For your car with points or Pertronix you can use either a standard or ballast coil and configure your wiring to match. The electronic ignition coils are often unique to OEM electronic ignitions and not necessarily for use with points or the Pertronix.

For a ballast coil setup (1-2 Ohm coil), replace the coil you have with a new ballast coil and wire the Pertronix per the picture Randall posted above. Done.

For a standard coil (3 Ohms), run a new white wire from a switched terminal on the fuse box OR directly from the ignition switch. The OEM wiring for the coil will be unfused. Connect the other end of the new white wire to coil (+). Run a wire (white/black if you can source one that color) from coil (-) to the points in the dizzy. For the Pertronix, put the red wire on coil (+) and the black wire on coil (-). Done.

 

[TR3driver]

Doug, I have wiring diagrams that shows the resistor wire for a 76, and the discrete resistor for a Mk IV (71-72). Doesn't prove anything, the diagrams are sometimes wrong, but that's why I think his 76 would have had a ballast wire originally. Of course, it might have been removed when the Mallory distributor was installed, but the voltage readings certainly suggest there is a resistance somewhere, and none of those things in his photo look like a resistor. (Two of them are relays, the one on top is a turn or hazard flasher)

Dan, if it were my car, I would look for a place to get 12v from the ignition switch, like the hot side of the top fuse, and run a new wire from there. Buy a quality aftermarket coil (I'm currently using a Pertronix), your choice as to whether it requires an external ballast or not (I'm currently using an external ballast on my TR3, because that's the Pertronix coil I had on hand). If you choose to have an external ballast, you'll also need an external ballast resistor and to follow the wiring diagram I posted above. If it's a 3.0 ohm coil (no external ballast needed), then use the non-ballast diagram in the Pertronix instructions.

The coil you have appears to be designed to work with the original electronic ignition, which I know very little about. It might work OK with the Pertronix, but it might not.

 

[Roger]

I'm only reading this thread from interest, and won't presume to give more advice than Doug and Randall, but I would like to make an observation.

The last photo shows the words COLD START prominently, and there are 3 low-tension terminals on the coil. These lead me to suggest that the coil may have an integrated resistor and bypass circuit, or something similar. I vaguely remember seeing such an object years ago.

I'll get me hat and go home now.

 

[TR3driver]

I agree, Roger. However, at this point, we don't know what's inside. It could be an integrated ballast resistor, or it might be an integrated diode used to bypass the external ballast resistor. Lacking that knowledge (and having recently been stranded twice by Lucas coils), I'd replace it.

Hmm, is it possible this Spitfire is not a US-spec car?

Oh, and BTW, feel free to jump in any time Roger. No need to be shy, or to let Doug & I dominate the conversation. I <span style="font-weight: bold">know </span>I don't have a direct line to <span style="font-weight: bold">The Truth</span> and I do frequently miss things, so the more heads the better.

And most of this comes under the category of opinion, which as we all know resemble nether sphincters. Everybody's got one and they usually stink.

 

[dklawson]

I agree. Please DO jump into the conversation.

I could not see the last picture until now (for some reason it would only appear as a red-X). I do see the "Cold Start" text Roger is referring to.

Like Randall, I don't see an external ballast resistor on this setup and the earlier coil pictures are very different from what I have seen installed on other LBCs. Perhaps it is an internal ballast coil of some sort with those (3) terminals. I just don't know.

I agree with Randall that I would choose which type of ignition you want (ballast or standard) and buy the desired coil type to match when you buy the Pertronix kit. Randall gave a good summary of the wiring changes above to suit either coil type.

Randall, like I said earlier I don't know what wiring a '76 Spit would have for ballast coil wiring. If your diagrams say there is a resistor wire in there... I believe you. However, I don't see it in the pictures Dan posted. Perhaps this is a Euro spec car and ignition system as you suggested.