Re: TR3 Pertronix conversion for Mallory Dual Poin
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I used the Mallory because I got a good deal on it and my original distributor was shot. Since I have headers it looked like the performance thing to do.
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Hi,
The Mallory Dual Point dizzy *was* a key performance upgrade in it's day and remains one of the few aftermarket dizzies available to directly fit the TR2-4A TRactor motor (okay, a drive dog needs to be fitted to the dizzy... but that's a simple process).
Actually *dizzies*/plural, there are a couple versions: one with vacuum advance, the other without, #2732001 and 2332001 respectively. There is also a third version, also non-VA, with a tach drive for aftermarket mechanical tachs, #2432001. These might be the only dizzies that are a direct fit to the TR motor. If anyone knows of one besides the Mallory and the original Lucas, I'd be interested to hear about it.
The original Lucas dizzy is pretty good, can be rebuilt fairly easily, and can be modified for non-vacuum advance and/or breakerless function. One of the "problems" with the Lucas is that there were quite a few different models, all looking very similar but with subtle differences, used in various TRs over the years. There might be some concerns if, say, a TR4A dizzy originally for use with the late cyl. head, exhaust manifolds and ZS carbs is fully compatible and interchangeable with a TR2/3 with earlier head design, 2 liter displacement, early exhaust and SU H6s.
The dual points help insure a strong spark and you sort of have a "backup" set of points installed full-time, in case one set ever slips or fails. A little system redundancy for the TR can't hurt. It's a very well made product, too. Service parts are a bit high, but then the Lucas stuff isn't cheap either. Plus, all Mallory dizzies are designed to be easily re-curved for centrifugal advance, to adjust for a specfic motor's needs.
Incidentally, the reason both vacuum advance and non-vacuum advance are offered is that VA is used with stock carbs (SU & ZS), but non-VA is needed with some aftermarket racing carbs such as Webers and Dellorto. The reason for this is there is simply no place to properly take-off vacuum from the Weber-style manifold, nor is it a good idea to create one (or more). The carbs are designed to run with each cylinder's intake isolated, for more precise tuning. A vac. port or ports on one or more of the manifold inlets will upset the balance (although the car will run and can be tuned to some degree to compensate).
I'm using a Dual Point on my TR4, but today I think I'd go with the Mallory Unilite dizzy instead (also avail. with or without VA, #4732001 and #4532001 respectively). In other words, I think I'd go straight to eliminating the points entirely. It's a little more expensive initially, but less than the cost of buying a Dual Point *and* later converting it with a Unilite module (part #562), plus there is the savings of service parts over the life of the dizzy.
Mallory also offers a variety of CD boxes, some with rev limiters and remotely adjustable advance, various compatible coils rated by RPM capabilities and breaker or breakerless design, power spike filters, plug wires, etc., etc. The same parent company that owns Mallory also owns Jacobs and Accel ignitions, so there might be some cross-over technology with those companies.
I know this sounds like an ad for Mallory, but, no, I don't work for them. Just a fan of their products!
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P.S. Unfortunately, there is no similar, easy answer for the 6-cylinder TRs. The problem is the tach drive is integral with the original Lucas dizzy on those cars, and replacements don't have the drive, meaning it will be necessary to change to an electronic tach if using an one of the Mallory dizzies. Mallory doesn't list it in their catalog, but I'm pretty certain their dizzies that fit Jaguar 6-cylinder will work on TR-250/5/6, as well, albeit without a mechanical tach drive.