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MG MGB Technical - flame-thrower electronic distributor

received several responses to a previous thread I submitted about switching to an electronic distributor
in my 1974 MGB.
I'm not familiar with the '123 electronic' distributor identified in the responses to my previous thread.
Specifically, I would like to know if anyone has switched from a standard distributor in an MGB to the 'flame-thrower' electronic distributor listed in the MOSS Motors and Victoria British parts catalogs.
My MGB is a 1974 but is fitted with a 45D4 standard distributor.
THANX!


L Rousselle

These are made in China, nowadays what isn't, and are of questionable quality. I've heard reports that their advance curves vary wildly from one unit to the next. I would steer clear of them. Jeff Schlemer can convert your old distributor to electronic operation as well as rebuild it for much less than a new unit. If you have your heart set on purchasing a new distributor, get the 123. I have a unit made by Davis Unified Ignition that is based on the '70s GM HEI system. The only drawback is that the assembly is huge, but it puts 50,000 volts and works quite well with my supercharged engine. RAY
rjm RAY

Has your engine be modified in such a way that it requires a specialized ignition system? The standard points type system works quite well for most applications and allows for easier trouble shooting if there is some form of engine problem. Hard to trouble shoot the electronic systems except by replacing with a "known good unit". Points systems, on the other hand, can be gone through is a systematic manner with test equipment common to the serious hobbyist.

Jeff Schlemer has a very good reputation with his distributor rebuilds and most of these distributors do need to be tuned and rebuilt after this many years of operation. Normal "parts store" rebuilds are often poorly done and way out of specification. Those that I have tested were so far off as to offer the potential of significant engine damage if installed and used for any period of time. Jeff, on the other hand, seems to turn out a quality rebuild, and this is the basis for a quality ignition system.

With your distributor rebuilt, you can, should you desire, install a Petronix Ignitor module inside the distributor and have your "electronic ignition" which should work fine for many years.

One of the selling points of many of these after market ignition systems is "It provides XXX thousands of volts". This is only partly true. Any ignition system based on a distributor and coil provides only the needed voltage to cause the spark plug to fire--nothing more. My tests show that my MGs fire at about 11K volts and the max voltage build up I have seen is 19K volts, well within the range of the standard distributor and coil. In fact, your Lucas 45D4 distributor was specifically designed to operate at higher voltages, without problem, when compared to the older Lucas 25D4 with was the first distributor installed in the MGB and one which worked fine for most people.

When "upgrading" to a system which claims higher output voltage, you need to upgrade the other parts of the system also. The spark plug wires, distributor cap, coil lead, and rotor, if they are required to constantly operate at the 40K to 50K voltages that some systems claim, will break down more rapidly than they would operating at the more common 11K to 19K output voltages commonly encountered with MGB engines. Cleanliness also becomes an issue. Anything which would allow the spark to jump along the outside of the spark plug, rather than inside the spark plug, will cause a misfire--e.g. a small amount of water on the plug for instance.

For the vast majority of people, a standard ignition system will work just fine as long as it is in good working order.

Les
Les Bengtson

I join in with the comments made by Les.

An electronic system is either working or in complete failure. No in-between mode and no advanced warning of impending failure.

As with the pertronix, if you have one installed carry a spare and/or the original points plate with you. These units will either last for years or fail within weeks or months.

A good set of points should last 8-10K miles or about a years worth of daily driving.

Have your decades old 45D4 distributor rebuilt by Jeff at Advanced Distributors. It will perform better than new and far better than any aftermarket import.
Steven Rechter

I have the (Moss) Pertronix "Flame Thrower" installed in our '74 B/GT now for about 3-years, and have no problems. Perhaps they are using a different source now, but the quality of the unit we have installed looks quite good?

Regards,

Larry C. '69 midget & '74 B/GT
Larry C '69 Midget

This thread was discussed between 09/09/2012 and 11/09/2012

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