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Dual point distributor?

Hey guys, how can you tell a dual point distributor apart from a single point? I have a Mallory distributor for my 1969 Chevy Nova, and when I purchased it it didn’t have any points in it. I put one point in but could I put another one in? Or just run a single point? It looks like it can fit a dual point: it has four evenly spaced screws on the top of the distributor,and there’s a hole drilled on each side with porcelain set in the hole. Any ideas?

It could well be a dual point distributor and adding a second set is quite possible and easy to do.
The only advantage of a dual point distributor is that the second set can help offset any high RPM misfires due to point bounce or what have you.

Unless you spend a lot of time at 6000 RPM, racing, etc then a second set is not a must.

I don’t remember having to deal with any dual point distributors on GM cars back in '72-'76, and our shop manager was the president of the local Corvette club. @ok4450 is right, they add complication, but not much in day-to-day performance.

The Ford ‘hi-po’ 289 had them, I wonder what others came that way from the factory.

Old technology. Why would mess with it? Just put in HEI and be done with it.

I was just thinking about HEI. That might be the best way to go.

All of the Chrysler, DeSoto, and Dodge hemis from 51 thru 58 had dual point distributors.

Adding a HEI is the easiest and best thing you can do…unless you want to keep this original.

I think the Mallory dual point distributor is aftermarket, they sell them for all kinds of engines.

A dual point distributor was also an option in 60s era Mopars and the Boss Mustangs also had them from the factory. The '59 Corvette I used to own also had a factory dual point in it.

A dual point distributor allows an increased dwell angle…In other words, they give the coil a longer saturation time at high RPM…They are tricky to set up properly, you really need a Sun distributor machine to set them up right…

Why mess with 60 year old ignition systems??

@Caddyman why mess with a 60 yr old system? Because I’m 70. I like old things! Haha

Sounds like a good challenge, I’d like to hear that engine once everything’s running right. Does Mallory have any tips/guidelines/instructions for you?

The old Mazda RX7 had dual points and not uncommon to run 7,000-8,000 RPM.

If you don’t know anything about duel points, you had better leave the dist. alone.

With 4 and 6 cylinder engines, a single set of points could provide adequate dwell time to completely saturate the coil and provide a hot spark even at high RPM…But with 8 cylinder motors, with 8 bumps on the point cam, the points are open longer than they are closed and dwell time decreases to the point the coil’s efficiency starts dropping at high rpm, there is not enough TIME to develop a strong magnetic field needed to produce a strong spark…

The solution was to use two sets of points, slightly offset from each other, to increase dwell time while maintaining a decent point gap…Now you can achieve 35-36 degrees of dwell instead of 28-30 which is what you get with single points in a V8 set at .017 or so…

I had a Mallory dual-point distributor in my GTO 35 years ago, and on the street it’s no better or worse than a factory single point distributor.

Do a simple Google search to see how to install and set the points, or contact Mallory to get that information. They’re simple and reliable, same as the factory distributor. It won’t make a street car any faster, but it won’t hurt anything either. If this Nova already runs with the original distributor there really isn’t any advantage to installing the dual-point.

But it’s yours, put it in if you want to, just be prepared to pay a LOT more for the replacement points when you tune it.