Accel Dual Point distributor

[johnny-d]

I bought a used Accel dual point distributor and am not sure how to hook it up correctly. Each set of points has its own wire running off of it and there is no vacume advance apparatus visible. Anyone have any experience with these set ups?

[Chryco Psycho]

Sounds like a race piece , probably has the cable Tach drive on it as well , both points wire hook to the insulated boss on the body of the dist which connects to the -  side of the coil , but I seriously doubt you want to use it , probably will not work well on the street , does it at least have mech advance??. The Mopar electronic will work way better than points anyway
 

[johnny-d]

Is there a way to tell if it has a mechanical advance (or not)? Both wires off the points exit the distributor through a rubber grommet and the points are adjustable (presumably with the engine running) using an alan wrench through small access windows on the sides of the distributor. My car does not have electronic ignition so I will be running an MSD box. The Accell rep I contacted said he had no info on the distributor but that if I am running the MSD I should only hook up the first set of points. My biggest concern is if it has a mechanical advance or not since it does not have a vacume one.

[BIG MIKE]

to change to electronic ignition is real easy, and costs alot less.  you just hook up one wire. the wiring costs about 20.00. if your interested let me know, i have a couple of books.  

[Yellow_Fish]

I used one of those for years. It was a good distributor. Only centrifical advance, no vacuum. You set it up one set of points at a time. That is why it has 2 wires. Both go to the discharge side of the coil. One wire should have a plug in it. You take the plug apart to set the first set of points at 32 deg. Then put the plug back togeather and set the total for 42deg dwell. The nice thing about the one I have is that it could be adjusted while the engine was running with an allen wrench.

It is still worth using and lends a bit of that classic look to your mill. An electronic ignition is  still better (but so is a blown Nissan 300ZX, if you get my point).

I Still have mine in a box. Actually I think i have a couple of different ones. I can go dig them up if it would help.

Mine (cuda) is back to stock now. The vacuum advance makes it a bit easier to drive (while eating a fries and coke) but is a definite disadvantage in performance.

[johnny-d]

Thanks Yellow Fish! Sounds like the exact same distributor I have. Do you have any recommendations with running this distributor in conjunctin with an MSD? The Accell guys said only hook up one set of points when running it with a box. Also, what makes the vacume advance "easier to drive while eating"? (I have never run a mechanical advance ditributor before).
Many Thanks,
Johnny-D

[Yellow_Fish]

Well, here's the deal, and you probably know most of this, but just for the record-

The dual point was designed to go with a stock or near stock rated coil. The problem with these coils is that at high revs they do not saturate well. So when they discharge, at the moment the points break open, the spark is not as hot as at low RPM's. This is overcome or at least improved with a dual point by doubling up on the contacts (less resistance) and, more significantly, extending the dwell angle to allow for a longer charge.

Now, with a high performance coil, this could be bad. High performance coils have less internal resistance. In some of these the longer dwell may cause overheating at low RPM's.

When a point style distributor is used with an electronic ignition the charge on the coil is switched through a transistor. So the points are only used to trigger the ignition. Depending on the ignition, extending the dwell may be a detriment. Your stock distributor may work as well or better in this case.

Now as to the fries and coke, or at least not having them end up in your lap-

Advance in an ignition system is important for producing power as RPM's increase. Your dual point is regulated only by engine speed. They tend to advance sooner and more than the centrifical advance on the stock distributor, although this " curve" may be tuned by changing springs or weights in either distributor.

Your stock distributor also uses manifold vacuum to adjust advance. The higher the vacuum the more advance. However, a stock distributor will not go to full advance on vacuum alone.

One of the effects of advancing ignition timing is to increase engine RPM's in relation to a constant throttle position. Imagine a car accelerating then decelerating. During acceleration the vacuum is not as high (normal street driving, not quarter mile runs)
So vacuum advance is less. When the operator pulls his foot from the accelerator vacuum goes up holding R's up as well. This makes for less "jerky" street driving but detracts from the control you need at the racetrack.

This is of course a bit oversimplified.

[johnny-d]

Thanks for the lesson YF! I found it very informative and after reading your explanation I can see why I should only hook up the first set of points I run it with the MSD box. I appreciate you taking the time to give such a detailed explanation.
Johnny-D