Distributor, Iron or Aluminum
 

Not sure what category this fits into but since it will be a street application I posted it here.

Mild build, limited use with old skool OEM points.

So, the pros/cons, if any, of using an OEM cast iron distributor versus OEM aluminum.

Never have found any diff over the years.Tom

The only difference I ever found was if you have one in a very unmaintained motor that causes it to be badly stuck, then you may break a aluminum body one getting it free.

I have found in the past that used cast iron ones are usually in better condition than aluminum. I guess it just depends on how well the engine was treated.

Observe dist bushings and shaft wear or slop, i have found the cast iron ones to have less wear

The solid ring that is machined on the body above the drive gear does a better job at directing oil to the bushings

Personal choice. I like the old school look of the iron distributor all painted up with it's Delco part number aluminum band on it. Obviously, it weighs twice as much. If your going to use an aftermarket brass dist. gear on it or the poly gear, you will need to drill the shaft for the larger roll pin the aluminum distributors use.

The older 1950's vintage cast iron ones had larger bushings that never seem to wear. As time when on Pontiac discovered they could cut costs by using shorter bushings. These later distributors can have slop in the bushings usually caused by poor maintenance of the engine over time.

The earlier distributors for the most part have more accurate machining of the lobes. Sometimes on later ones the lobes are not perfectly 45 degrees apart.

For example what we have noticed is that a distributor can have #1 & #6 lobes machined exactly 180 degrees apart. Then #2 & #3 are 180 degrees from each other but, are they are machined 46 degrees from the previous lobe.

Then #4 & #7 lobes are machined 46 degrees from their previous lobes but still 180 degrees from each other. The addition degree in both lobes pairs makes the #4 & #7 92 degrees away from the #1 & #6 lobes.

Then the machining process somehow detected the error and the #5 & #8 lobes would be at 43 degrees from the #4 & #7 lobes and the #6 & #1 lobes. That would ensure that the #6 & #1 lobes would be machined perfectly.

This isn't something that would be noticeable to the average motorist. I am guessing that at some point GM lowered the quality standards for the lobe machining in order to save some money. Hard to believe that would happen.

This is a difficult to explain subject but it is as clear as a bell when testing on a distributor machine. You can get a idea in the video by looking at the flashing arrows around the distributor. The presentor in this video never checked or mentioned anything other than the #6 lobe.

https://youtu.be/fh0jXS1p3bY?si=iCXyqyF8DOVr2M47

We have both in service here. Doesn't matter to me either way. The iron ones we have do have the little oil trap tube so you can service it once in a while and add a few drops of oil.

I wonder how many people actually paid attention to that over the decades.

I get excellent service out of either design. Pick your poison.

Thanks guys for all the info. I tend to overthink things but I just figured it would be good to get some feedback from members more familiar with the details of these two distributors.

You can clone the '56/'56 cast iron ones into super duty distributors. Remove and pin the vacuum advance - filling in the side of the body where the arm went through, have a trophy shop engrave the correct part number on a replacement side plate and put it on, buy a new Corvette cap, and it will look identical to the real deal.

Here's a cloned sd distributor. Kind of off topic but I'm bored this morning.

Iron with single points and MSD all day, everyday.
I have yet to find a iron distributor all worn out and sloppy. Found plenty of aluminum ones and they are all newer.
Tells you a lot. Larger bushings oiled better is my guess.
Only better ignition is a crank trigger.

I am and always have been a BIG fan of points distributors. They are dead solid reliable in long term service. Problem with HEI's, especially aftermarket stuff, it will fail sooner or later, and most likely you woln't be sitting in front of Jegs or Summit Racing when it does!

The downside of points these days is finding good ones. I use and prefer USA made Delco points and frequently buy them NOS from Ebay for distrbutors that I build here..

As far as aluminum or iron, about the only difference if the shaft and bushings are in good shape is the weight.......

http://forums.maxperformanceinc.com/...1&d=1702863051

Thanks for the reminder, just picked up a couple sets.

What's a good GM condenser part number for a 68 Pontiac?

1932004 are still readily available.

About 2/3rds of the time I buy the points and condenser sets together so don't have to shop for condensers.

I would for sure avoid just about everything that's currently available from the parts stores as most of it is made offshore and very poor quality. NAPA still offers (or did couple of years ago) a high quality uni-set, but there are very expensive and I trust the USA made Delco Remy points better. I currently have 6 sets in stock and since I'm retired and not doing much of that sort of work should be good to go for quite a while.

I'd add here that you do NOT need higher tension points sets for these engines. The stock points are fine for the RPM range these engines run in.....

I'm comfortable with points condensers in my rpm range. I guess electronic for higher rpm range. I too have a small stock of points and condensers (I even saved old ones). A small stock of parts to rebuild alternators and starters. Frankly I have no idea how many parts I have stocked!