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Mallory distributor on a +8

Posted By: vbalddave

Mallory distributor on a +8 - 17/05/22 12:14 PM

I'd be interested to know if anybody else has a Mallory distributor (Part No. 4768901H) fitted to their +8? The standard Lucas ignition set up (distributor and amplifier) was replaced on my car by a previous owner with aforesaid Mallory distributor, and it has proved something of a challenge over the past couple of seasons, due in no small part to conflicting information on the internet regarding whether a ballast resistor is needed, and which coil to use. Mallory stated a ballast resistor was always needed (that also being the received wisdom) but Holley - who took over Mallory - stated that providing the ignition coil was 1.4 ohms primary resistance or greater, no ballast resistor was needed.

Without boring everyone to death, I now have a collection of coils and a few Mallory pick-ups, all due to assorted failures and/or mismatched bits of kit. I am now running a ballast resistor and a 1.5 ohm coil, and at least the car is running well at lower and higher rpm (and goes further than the expiry 50 yards from home that happened on the way to the first sprint this year).

So....if there's any Mallory users in +8s, what set-up do you have, please?

Posted By: RichardV6

Re: Mallory distributor on a +8 - 17/05/22 01:08 PM

Both advice could be true Dave based on coil used. The primary resistance mentioned relates to the voltage at which the ignition coil is designed to work continuously with full battery volts, which could be anywhere between 12.2 and 14.5 volts dependant on battery state of charge, though usually closer to latter.

A coil with lower than 1.4Ω one can assume is designed to work with ballast resistor to drop to its lower continuous design voltage, except when starting of course when it's out of circuit.

If you've found a combo that works though obviously stick with it.
Posted By: vbalddave

Re: Mallory distributor on a +8 - 17/05/22 03:37 PM


Thanks for your you will have already ascertained, my knowledge in this area is less than comprehensive. I am led to believe that the issue relates to the Mallory opto-electronic pick-up, which eventually fails if it is exposed to 12v; it allegedly requires the notably lower voltage resulting from having the ballast resistor in the live coil feed. I'm hoping that the present set-up is the solution. It's been a frustrating journey to get here, as - whilst Mallory Unilites have a good reputation for quality engineering and reliability - there's no definitive edict regarding how to set them up. Hence I thought I would at least post on the forum to see whether I'm in a minority of one, or whether someone else has the magic configuration.

If I have any more issues (here's keeping my fingers crossed that I don't) then reverting to the standard ignition set-up would at least mean the "use this distributor/amplifier/coil" is well defined....along with perhaps carrying a spare rotor arm and amplifier unit.

Posted By: Treesurveyor

Re: Mallory distributor on a +8 - 17/05/22 09:11 PM

Dave, i'm not suggesting you change over. but chaps on this FB forum may have more users of your system to offer more advise.

Link FYI
Posted By: vbalddave

Re: Mallory distributor on a +8 - 18/05/22 06:38 AM


Many thanks - I didn't know that this one existed, so I'll join up and plumb the depths of the knowledge there, too.

Posted By: Treesurveyor

Re: Mallory distributor on a +8 - 18/05/22 08:55 PM

Hi Dave, you're welcome. I have an aversion to "modern" plug n play or throw it away garages, and whilst I respect traditional knowledge and experience cost, hourly rates are frighteningly high, so any forum of diy enthusiasts for research and encouragement is exceptional value- e.g TM! Sometimes on the other sites you have to filter out/bypass the odd childish argument/trolling, but on the whole that one's pretty good. I hope you manage to get well tuned.
Regards Phil
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