Ballast resistor

Technical advice Q&A

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whitesnake
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Location: Biggleswade Beds
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#1 Ballast resistor

Post by whitesnake » Wed Jan 23, 2019 5:19 pm

I have a series 2 OTS 1970 4.2 engine which has been fitted with a Petronix electronic distributor by the previous owner. It runs and starts absolutely fine and is a pleasure but on checking the ignition system I note it still has the ballast resistor fitted.
My question to the knowledgeable is can this now be removed with no issues considering that the petronix distributor should compensate the voltage to the coil automatically after starting.
I have read that the ballast resistor does this job for a normal points system ie: reduces the voltage to coil after start up to help economy, but have also read that the petronix system compensates for this anyway.
Any advice on this gratefully received, I do not want to remove it and find it causes other problems like overloading the coil.
Thanks Steve.
Steve White
1970 series 2 OTS

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cactusman
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#2 Re: Ballast resistor

Post by cactusman » Wed Jan 23, 2019 5:58 pm

You would be best to consult pertonix but as it works fine now I would not remove it.
Julian the E-type man
1962 FHC
1966 MGB....fab little car too

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mgcjag
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#3 Re: Ballast resistor

Post by mgcjag » Wed Jan 23, 2019 6:58 pm

Hi Steve.....Are you talking about a complete Pertronix distributor...or the points replacement Ignitor...if the later then see note 3..do not remove resistor
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Steve
69 S2 2+2 (just sold) ..Realm C type replica, 1960 xk150fhc

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Topic author
whitesnake
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#4 Re: Ballast resistor

Post by whitesnake » Wed Jan 23, 2019 10:18 pm

mgcjag wrote:
Wed Jan 23, 2019 6:58 pm
Hi Steve.....Are you talking about a complete Pertronix distributor...or the points replacement Ignitor...if the later then see note 3..do not remove resistor
Image

Image
It is complete distributor D177600 flamethrower, I see the note though and maybe leave as is while everything is working OK.
Steve.
Steve White
1970 series 2 OTS

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Paul71a
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#5 Re: Ballast resistor

Post by Paul71a » Thu Jan 24, 2019 6:05 am

I have some experience of the pertronix on my S2 E, albeit the points replacement system rather than the whole dizzy.

Your coil will be matched for a ballast resistor system, so removing it will need a coil replacement, so leave it be. However, the important thing is that your pertronix has a clean 12v supply and is therefore the red wire is wired to the supply before the ballast resistor, not from the coil terminal. See the diagram in the post above.

I’ve had experience of the pertronix going haywire (and sending the tach into nutty mode!) when the red wire was wired to the coil terminal, and mine has the ballast resistor removed. They like a nice, clean, switched 12v supply.

Paul
Paul Brazier. S2 FHC 1970, silver with blue leather. Oh, and a S1 prototype Lotus Elise and a Ferrari 488 GTB

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Topic author
whitesnake
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#6 Re: Ballast resistor

Post by whitesnake » Thu Jan 24, 2019 3:56 pm

Thanks Paul for info, this leads me to leave all as it is considering the engine runs really sweet and changing things is not really necessary. All I was considering was removing clutter and keep things simple but it seems with the coil I have the ballast resistor is part and parcel of the set up, I did not really trust the previous owner on his set up but it appears on this occasion he was correct.
Steve. :salute:
Steve White
1970 series 2 OTS

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