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MG MGB GT V8 Factory Originals Technical - Mallory Twin Point Electronic upgrade.

Happy New Year Folks

I have a new Mallory twin point dizzy and have booked my car in to be tuned / set-up.
The engineer recommended that I up grade from the twin points to the optical Mallory upgrade. I have since found out that this upgrade would mean losing the vacuum advance option. I do not want to do this.
I have been now been recommended to add a power amp instead.

Do you Guys agree this Power Amp would be a good idea, as although it costs about £140 I have been having trouble starting.
(The starting problems I hope will be greatly helped when I get the carb set up correctly)

I would also be interested if it is generally agreed that going to electronic is worth the ciost?

Regards
Dave
D M Tetlow

You fail to tell us how the car is used. Since you want to maintain vacuum advance, I assume it is street driven, not an all out racer.

Best advice for street is a stock distributer, perhaps re-curved, since it is in a MG (?) not a Rover, with a Pertronics conversion. This has all the benefits of the optical Mallory and still has vacuum advance. Cost on this side is around $80.00 USD. It is a 2 wire hookup, and is barely detectable if you want a stock look.
Jim Stuart

Do a little more checking. Some dual point distributors use the unilite housing and the optical module can be installed and the vacuum kept. I have done this on a BOP/R Mallory dual point and still have it on the spare engine. It simply bolts onto the existing breaker plate instead of the points. Even if it is not a unilite housing I think that would work. Both mechanical and vacuum advance is tuneable to approximate the stock advance curves.

Jim
Jim Blackwood

Thanks Jims.
The set-up is very basic. I have a std cam with 9.75:1 pistons with SD1 heads, and a Block Hugger ceramic coated twin SS system.
I hope to get a power figure soon when I get her tuned but I expect about 160BHP. This is enough for me at the moment.
I have not been able to get a conversion here in the UK so I will now look in your neck of the woods.
Thanks for the help.
Dave
D M Tetlow

Dave,
I also use a Mallory dual point with vacuum advance. I really think you should look at simply getting a higher output coil (I use the Mallory coil and dropping resistor). Dual points work quite well and give increased dwell which results in a bigger spark. Switching to an optical trigger versus the points really isn't going to do anything for you.

I also switched to NGK plugs from champion and that helped a lot. So, if your plugs and wires are in good shape, and it's got proper carburation, it should start quickly.

My setup is 10.5:1 compression, Isky 270 cam Offy 5165 intake, a Holley 390 4 bbl, block hugger headers and the Mallory dual point dist. Exhaust is 2 1/2 dual into a magnaflow muffler that has 2 inputs and 2 outputs. Loud but great sound.

I have my timing set up pretty high and use a mixture of racing gas and premium. And it runs like a bat out of hell. The plugs tend to have a red look due to the racing gas, but the exhaust is clean (not rich). It does flood easily when cold (big accelerator pump on the Holley) and once flooded, just won't start. That's my only gripe. Once warmed up, has a medium lumpy idle at about a 1000 rpm. I am using those spiral wound ignition wires and if I had it to do over, I would use solid wires. (radio? yeah if I turn it up really loud)

I think you should stick with the points.

Richard
Richard Morris

Maybe the biggest advantage of the optical trigger (or pertronics ignitor which is hall effect) is that the points will no longer need to be touched. I know, it doesn't take long to do that, but it's one more maintenance item. An electronic booster module such as MSD, HEI or any other number of brands and types can take care of the fat spark. Of course if you're concerned about it, most wouldn't stand up to EMP.

Jim
Jim Blackwood

I use the MSD Pro-Billet distributor for the Buick 215 (MSD PN 8548) in my Oldsmobile stroker with a MSD 6AL box...works great no vacuum advance but it has a great adjustable mechanical advance mechanism.
Michael S. Domanowski

I ran across this brief MG based article on the Mallory distributor.

http://www.formatc.org/mgb/articles/mallorydual.htm

Summit Racing is also a good source of parts, there are their distributors. Remember, the Buick dist, will work as long as you put the oil pump drive on the end of it.

http://store.summitracing.com/egnsearch.asp?N=700+4294925143+4294881256+4294908256+115+4294840103

Let us know which way you go on the decision.

Richard
Richard Morris

All true, plus if you burn up the secondary points (break) you can run on the primary points simply by swapping them into the secondary position. BTDT. But as a mechanical device it will always be a maintenance item no matter what you do. Crank trigger is maintenance free and error free, that's what I like.

Jim
Jim Blackwood

I hope to get an upgrade kit from The States, but I will keep the points handy in case of failure.
Does any one know of an electronic system like this failing?
I have never heard of one!
Dave
D M Tetlow

This thread was discussed between 11/01/2007 and 13/01/2007

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