I fitted a Pertronix Ignitor and retained the ballast resistor/Lucas coil combination on the advice of Carl Dudash at Retro Rockets Marvin Grebow at Pertronix...and had no issues at all (with the Ignitor module fed at 12V) - either with the ignition or tacho.
Copy of my email exchanges... (you need to start at the bottom and work up)
Stan,
Thanks for the diagram. The Ignitor should work with your tachometer with no problems. If you have problem installing a 10K ½ watt resister in line with the tachometer wire and coil negative should fix any problems.
If you have any further questions feel free to contact me.
Marvin Grebow Jr.
PerTronix Inc.
Technical Department Ext. 1030
marving@pertronix.com
From: Stan [mailto:vaultsman@ntlworld.com]
Sent: Monday, April 13, 2009 10:36 AM
To: 'Marvin Grebow'
Subject: RE: Ignitor set-up for Rover V8
Hi Marvin,
Circuit diagrams attached, vehicle is negative ground. Tachometer (#37) hooks up to the negative terminal on the coil (#44).
Regards,
Stan
From: Marvin Grebow [mailto:marving@pertronix.com]
Sent: 13 April 2009 16:10
To: 'Stan'
Subject: RE: Ignitor set-up for Rover V8
Stan,
How does your tachometer hook to the coil, the positive terminal or negative coil?
Marvin Grebow Jr.
PerTronix Inc.
Technical Department Ext. 1030
marving@pertronix.com
From: Stan [mailto:vaultsman@ntlworld.com]
Sent: Friday, April 10, 2009 8:39 AM
To:
marving@pertronix.com
Subject: FW: Ignitor set-up for Rover V8
Hi Marvin,
Carl suggests I mail you regarding whether the Ignitor setup will affect the tacho on my 1973 Rover V8? (Car details below)
Regards,
Stan
From: carl dudash [mailto:retrorockets@snet.net]
Sent: 10 April 2009 16:07
To: Stan
Subject: Re: Ignitor set-up for Rover V8
Stan,
The Ignitors are compatible with most factory tachs but I'm not certain about you Rover. Please email Marvin at the PerTronix Tech Dept with your question at
marving@pertronix.com
Thank you.
Carl
Retro Rockets
Stan wrote:
>
> Many thanks for your email Carl,
>
> Just one more question if I may: Are you aware any issues with the tacho after fitting?
>
> Regards,
>
> Stan
>
> From: carl dudash [mailto:retrorockets@snet.net]
>
>
> Sent: 10 April 2009 13:57
> To: Stan
> Subject: Re: Ignitor set-up for Rover V8
>
> Stan,
>
> I assume you looked at out Lucas page to determine that your 35D8 takes the LU-181. There are two versions of the 35D8 that take different Ignitors as shown on the page below:
>
>
>
http://www.vintageperformance.com/retro ... /lucas.htm
>
> If you haven't already done so, please check the 35D8 pictures on this page to compare with what you have.
>
> 8 cylinder Ignitors are designed for 1.5 ohm coils. If yours is newer and in good condition there would be no reason to replace it. If you need a replacement the 1.5 coils are listed on the page above.
>
> It is permissible to remove the resistor wire when running a 1.5 ohm coil with the 8 cylinder Ignitor. However, on a stock engine there would be no advantage. With a stock engine the best setup would be to leave the resistor in the coil circuit but to run a full 12 V line from the ignition switch to the red Ignitor wire. The source must go through the ignition switch so that there is no power to the Ignitor when the key is off. This would automatically avoid any possibility of low voltage to the Ignitor. Leaving the resistor in the coil circuit would allow the coil to run cooler. With the Ignitor in place you would still have significantly more spark energy available than with points if your engine needed it.
>
> Your instructions will show a wiring diagram for this setup.
>
> Thanks for your email.
>
> Carl
> Retro Rockets
>
> Stan wrote:
>>
>> Hi,
>>
>> I’m planning to change from points to electronic ignition, and am considering the Pertronix Ignitor.
>>
>> The car is a 1973 Rover P6B 3500 V8 with a Lucas 35D8 distributor (circular baseplate), 1.5 ohm coil, and a resistor wire in the loom which is by-passed when cranking.
>>
>> As far as I can see I need an LU-181 Ignitor, but what coil? And would I need to bypass the resistor wire and re-feed the coil with a new 12V ignition-switched supply?
>>
>> Kind regards,
>>
>> Stan Barnes
>>
>> Leicester, UK
