would dual points give the same advantage as MSD(multiple spark) ? at least at low rpm?

 

Dual pionts were the old school way to deliver a hotter spark. Stick with the newer electronic stuff, you won't regret it.

--Mike

 

Spend your money elsewhere than on the MSD etc stuff. The OEM electronic ignitions (except for the TFI) work better for anything but an all out race vehicle operating at very high RPMs.

 

Dual point is far inferior to modern Electronic ignitions. If for no other reason, maintenance. Electronic is capable of more accurate ignition, hotter spark, and longer spark duration. I would have to disagree with the earlier post that MSD Ignition is no better than stock except in all out race applications. MSD, Mallory, Jackobs, Crane, And Accel all offer degrees of tunability you can not achieve with stock. You have a lot more control over timeing curves, preset advances or retards, rev limiters, etc. You can add dashboard timeing control. Its kind of neat to be able to twist a **** on the dash and be able to run 87 octane gas, when your engine is tuned for 93.

 

The aftermarket units do add a lot of bells and whistles but they are not required in anything but a very few applications, mostly in race applications. They do not perform any better than the OEM units unless you need ignition in the 6000+ RPM range.

Building an engine to run on 93 octane then running it on 87 is a waste and is probably not tuned optimally for either condition.

Dual point ignitions were designed years ago to provide an early make for the coil charging circuit. The points that opened and triggered the coil needed to open and remain open to break the circuit, cool off, and clear the conductive plasma formed when they opened. The amount of time the points were closed determined the amount of energy that could be built up in the magnetic field in the coil. The larger magnetic field would produce the higher voltage required to jump the plug gap in high compression engines. The dual point design also provided more time to build the magnetic field for high RPM engines.

The modern electronic ignitions have high speed transistor or mosfet switching elements that are able to turn off breaking the circuit and then back on again very quickly. The only real limit they have is that they still need to wait for the magnetic field to collapse and the spark to occur.

The multiple spark units provide additional sparks at low RPM's that come to late for optimum timing. If the first spark did not light off the mix you have other problems that are robbing you of power to find and fix. If the multi spark units make a difference your engine is sick and you are just applying a band-aid. An expensive and poor one at that.

 

Thanks Tourque1st for your explination. As I understand it the points or the transistor are both only switches in the end. The transistor is just a faster switch. At low rpms there may be very little difference, say below 3500 rpms. This is mostly a hypothetical question as I am pretty well committed to my old school project truck. I have a goal of keeping the old truck going as long as possible with things I can do or learn. Part of the fun is maintenance I can do, like points. Since I already have points and I don't require high rpms, no changes are necessary maybe.

 

I have run a single point distributor as far as 9000 RPMs on an engine with 12.5:1 compression and it worked. That engine required a new set of points and plugs every 2-3 weeks tho, -otherwise my mileage went from 8 MPG down to 4 MPG. 115 octane gas was only 25¢/gallon back then and plugs were not very good.

 

I would have to say as good as single and dual points were, even the Motorcraft stock electronic systems designed in the mid 1970's are even better. When I built my engine nearly 20 years ago, I chucked the points in favor of the Allison optically triggered electronic system. This was far more reliable than the points and it allowed me to generate and use far higher voltages through the plug wires.