Not trying to hijack your thread, but if you already have a points distributor, why would you go to an HEI? I see this change quite often and wonder why?? What is so wrong with a points distributor?? It worked well at one time. Can it have something to do with changing the points every so many thousand miles?? That's not a big deal. Besides, how many miles do we put on these cars during a season?? I read more threads with problem HEI distributors then I do the point ones. I admittedly have an HEI distributor in my '71 GTO, because it came with it. I also bought a used point distributor. The first sign of trouble with the HEI, in the garbage it goes. I know I'll need a coil and resistor, rewire some, but that's ok. By asking these questions, I'm just trying to learn something. Many thanks.
From what I gather, the HEI was developed to meet Federal requirements that the emission systems to be warranted for 50,000 miles. Points won't last that long without maintenance, but an HEI usually will. The cars of that era also ran leaner mixtures which demanded greater voltage and more spark energy to kick off combustion. So the HEI is seen by some as a lower maintenance item.
Points will always give you a "heads up" when they are going bad by running rough. When the module in an HEI quits, no warning and it can leave you stranded.
The HEI when first out was not really designed for high RPM and was not very good over 5,000 RPM's. The advance curves were also The advance curve on a stock HEI is for the most part not fully advanced until 4,000-4,500 rpm, which is very slow. If your low-end cam power band begins at 2,500 rpm (or below), then your advance curve will not be matched to your camshafts power-band, which will result in a significant horsepower/torque loss.
The HEI provided a longer spark dwell and hotter spark so low to midrange motors benefit from a more intense spark from idle, all the way up the entire rpm range as the fuel is burned more completely. Since the HEI produces more voltage and amperage output than a point-type ignition, it required a larger-diameter cap to prevent voltage crossfire inside the distributor cap. The large cap also offers extra space to host the coil, making the HEI distributor self-contained. It also allowed for a wider spark plug gap for a more complete burning of the fuel mixture.
Is the HEI really any better than points? I guess that depends. Most today have no clue on how to set up points and have been convinced that electronic ignitions are the only way to go. You need a tach/dwell meter to really set them up correctly - and that's an extra "tool" that many either don't want to invest in or care to understand its use. Want more dwell, use a dual point distributor or and MSD box. Hotter spark? Upgrade to a hotter coil. Need stability at higher RPM's, get a set of points designed for more RPM's having additional tension on the points.
For me, electronic ignition is a convenience and in my mind, dependable over a longer period of time. It will outlast points in the long run, but will/can leave you stranded if the module quits on you. You can either keep a spare set of points in your glove box or a module.
As far as more power from the engine, take a look at this comparison done by Hot Rod. Points seems to be the winner up to about 6,500 RPM's - which is probably when points begin to bounce unless you have the heavy duty set. What the test does not show
, as this is a stock distributor, is how the distributor might actually outperform the electronics if they first threw in the results of a dual point distributor designed for higher RPM's and then adding an MSD or other unit that enhances spark.
So the bottom line appears to be, no real advantage in the functionality of an HEI over a points distributor unless you begin to go higher in RPM's - which I think could be matched by setting up the distributor to handle the higher RPM's just as they did in drag racing past. The only advantage to HEI is not one of functionality, but longevity and reliability from the module over a greater period of time/miles versus points.
Ignition Performance Test - Hot Rod Network