Ballast Resistor Wire

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bbodie52
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Re: Ballast Resistor Wire

Post by bbodie52 »

erco wrote: » Wed Sep 09, 2020 1:45 pm

Just received this email reply from Pertronix after asking which Flamethrower coil to use:

"You need to use the 3.0 ohms coil when not using a ballast resistor."

Your Pertronix Team,
Marvin Grebow Jr.
Technical Dept.
Assuming he is talking about your 6 cylinder Corvair, his guidance...

...matches their usage chart (below)...

Image
I believe their engineering/design/application theory goes something like this:

The Pertronix instruction sheet consistently advises installers to bypass/remove the ballast resistor or resistor wire from the primary circuit. This is intended to feed the Pertronix Ignitor (I or II) electronic ignition (breakerless) control system with full battery voltage (nominal 12 VDC). This is the correct voltage that the electronic module was designed for and it is what the design engineers expected it to be powered by. The instruction sheet tells the installer to connect the red Ignitor power wire to the positive terminal on the ignition coil, which will be a decent source of 12 VDC battery voltage (after the ballast resistor has been bypassed) that is switched on and off by the vehicle ignition switch. At the same time, the ignition coil will have been upgraded to a high performance ignition coil like the Pertronix Flame-Thrower 40,000 Volt secondary output coil. THIS COIL IS DESIGNED TO OPERATE ON 12 VDC BATTERY VOLTAGE. However, Pertronix also recommends the use of the Flame-Thrower 3.0 ohm coil (at 12 V) on 4 or 6 cylinder engines, or the Flame-Thrower 1.5 ohm coil for 8 cylinder engines. The difference is the expected DUTY CYCLE (the cycle of operation of a machine or other device which operates intermittently rather than continuously). The 4 or 6 cylinder engines have only 4 or 6 distributor cam lobes, so the amount of time at any given engine RPM that the ignition circuit is ON (closed) and feeding power to the ignition coil is LONGER than the duty cycle in an 8 cylinder engine (which has more distributor cam lobes switching coil power on and off during each crankshaft revolution). The shorter duty cycle (coil charging time) in an 8 cylinder engine means the coil needs a higher current level to fully charge in the available duty cycle time. At 12 Volts, 1.5 ohms of primary resistance, instead of 3.0 ohms, means more electrical current flowing. This is right for a V-8, but would cause a 1.5 ohm coil to run hotter on a 4 or 6 cylinder engine. THAT IS WHY THEY SPECIFY 1.5 OHMS FOR A V-8, AND 3.0 OHMS FOR A 4 OR 6 CYLINDER ENGINE. At 12 VDC, the current flow is optimized for the coil duty cycle by selecting the correct primary circuit resistance of either 1.5 ohms (for V-8) or 3.0 ohms (for 4 or 6 cylinders). Capisce?

Image

At 12 VDC, you can still use a 1.5 ohm coil with a Corvair 6-cylinder engine, but it should be in conjunction with an external 1.5 ohm ballast resistor or resistor wire. However, doing so would drop the feed voltage at the coil positive terminal to approximately 7 VDC, so connecting the Pertronix Ignitor inside the distributor to the coil positive terminal would under-power the Ignitor electronics — with only 7 VDC instead of 12 VDC. In such a case the Pertronix Ignitor red wire should be connected to the ignition primary circuit BEFORE the ballast resistor or resistor wire, which is where 12 VDC that is switched on and off by the ignition key is found.
Brad Bodie
Lake Chatuge, North Carolina
Image 1966 Corvair Corsa Convertible

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Mcwho
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Re: Ballast Resistor Wire

Post by Mcwho »

I am just getting into this issue on a 65 110 engine. After replacing tbe points w the ignitor 1 module, realized i had surginv goind on. So got the flametbroqer 3 ohm primary, and the directions lay put hpw to tell if there is a resister in there. My coil b+ to the + terminal on the coil is about 7.6 volts. So i need to switch tbe source of the coil to a source that is near 12 volts, or maybe a relay tho connect the batt b+ to tbe coil. I am wondering if there is another b+ that i could use.

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1965 Corvair Monza Coupe 110, 4 speed, Liberty Blue

joelsplace
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Re: Ballast Resistor Wire

Post by joelsplace »

I think most people splice in at the firewall connector just ahead of the resistor wire.
114 Corvairs, 5 Ultravans and counting
Northlake, TX

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Mcwho
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Re: Ballast Resistor Wire

Post by Mcwho »

Can anyone tell me what tbe ballast resistor wire looks like? I see the connectors just inside the engine compartment and will have to cut tbe black covering to get at it.

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Re: Ballast Resistor Wire

Post by bbodie52 »

It is a wire that extends from the 12-pin multi-connector to the two-pin starter solenoid connector. The wire between these two points is the special resistor wire. In the schematic diagram below I represented the resistor with a gold coil of wire and a gold label pointing to it. At the starter solenoid 2-pin connector it is spliced to another wire that continues on to the ignition coil Positive (+) terminal, but that segment of wire is just normal 20 gauge wire labeled 20 B/Y (20 gauge Black/Yellow Stripe)

The wire on the other side (firewall side) of the 12-pin multi-connector is labeled 20B/P (20 Gauge Black with Pink Stripe). On that side of the plastic connector, the wire is also normal standard 20 Gauge wire that leads to the dashboard, where it is connected to the ignition switch to provide power when the key is in the ON position. Only the short wire segment between the large multi-connector and the small starter solenoid connector is special resistor wire, labeled 20 W/R/B (20 Gauge White/Red/Black)

Left-click the image to enlarge for better viewing. Click a second time for maximum enlargement...
1965 Corvair Monza Full Schematic
1965 Corvair Monza Full Schematic

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Image

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Brad Bodie
Lake Chatuge, North Carolina
Image 1966 Corvair Corsa Convertible

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Mcwho
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Re: Ballast Resistor Wire

Post by Mcwho »

Thanks for the indetail help. I should be able to find that resistor wire now.
Bob

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Gregory_Miller
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Re: Ballast Resistor Wire

Post by Gregory_Miller »

I left the ballast resistor in place and installed a bypass wire to provide the full 12V to my Pertronix. Used the FlameThrower coil with the standard coil impedance and ignition has not been a problem since. I did have a bad stock impedance Bosch branded coil that sucked causing me issues before it was discovered. First it was replaced with a stock Corvair coil then I got the FlameThrower. It can be done different ways, decide which one is right for you. Just make sure all the parts are correct for whichever way you decide to go.

erco
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Re: Ballast Resistor Wire

Post by erco »

Gregory_Miller wrote:
Thu Sep 24, 2020 1:38 pm
I did have a bad stock impedance Bosch branded coil that sucked causing me issues before it was discovered.
Not my Bosch big blue coil! I've hade mine forever and plan to keep using it forever!

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Gregory_Miller
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Re: Ballast Resistor Wire

Post by Gregory_Miller »

Glad your experience was better than mine. My Bosch coil was black and puny.

erco
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Re: Ballast Resistor Wire

Post by erco »

Mine is like an old friend. Mind you, my engine hasn't run in 20 years but the coil is still in excellent shape, low miles and I plan to use it again soon.

Related, I found a great price on this coil ($39 includes tax & shipping) at https://ljaircooledengines.com/products ... 3179825265 . But a Pertronix Flamethrower coil is not much more, I would probably go that way if mine craps out.
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erco
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Re: Ballast Resistor Wire

Post by erco »

Oh, so THAT'S what an OEM Corvair ballast resistor looks like. How'd I miss THAT? Hurry, only 2 left!

https://www.walmart.com/ip/OE-Replaceme ... /438076497

(Noobs: Sorry for any confusion, this badly mistaken listing is just wrong. Corvairs uses a resistance wire integrated into the wiring harness)

ec565bdf-dab1-4ed9-9970-96f395c5a03f_1.6bf941761bb63e353fa110f4b15281ca.jpeg
x2.jpg

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