Making the Switch From Points to HEI:
To start off, the earlier Caddys used a points type distributer. I'm not quite sure, but I think the HEI ( High Energy Ignition) was introduced in '73 or '74. Upgrading from points to HEI is not hard, and will really help performance on the cheap. However, there are a few things you will need to know and do to make the switch.
Just for some physical recognition, here are pictures of each:
Points type distributor
HEI distributor
HEI distributors can be found pretty cheap on Ebay and in the yard. Accel and MSD also make HEI units that fit the Cad 500, but won't be of any real gain unless you are racing or have a very high performance build. Almost any HEI unit you find on Ebay or wherever will be in need of a freshining up. MSD, Proform, and Pertronix all make "hop up" kits. A word of advice. Use the STOCK springs. The proform kit (and maybe pertronix) come with a "performance spring and weight set". These are chineese crap, and not nearly as good as what is in there already. Don't worry, the stock springs and weights aren't going to be worn out. Also, something that may not be included in these kits is a vacuum advance unit. If you pick up an HEI distributor with one that no longer works, you can usually find one on the net or at the parts store pretty easily.
The HEI distributor is a direct drop in, but you have to remember about some things:
SPARK PLUGS. With points, your BBCad will have plugs with a gap of, if I remember correctly, .035. If you were to visit a parts store, you would see that later Cads, such as the '76 Eldorado, have spark plugs with a much bigger gap due to the fact that they have HEI. Replacement spark plugs for a vehicle with HEI will be those with a .060 gap, so remember to get the larger-gap plugs! I would also suggest getting resistor type plugs to increase the spark duration and get the most out of your points to HEI switch.
SPARK PLUG WIRES. Yep, you will need some new spark plug wires as well. One Item overlooked in the HEI swap, is the need for new plug wires. The GM HEI, and a lot of aftermarket replacements, use a male connection on the cap, kinda like the top pf a spark plug, while the point's style has a female connection on the cap. Therefore, you need to get HEI type spark plug wires.
INSTALLATION. You can't forget about the physical installation of the HEI unit. Use pieces of tape, or scribe lines, to mark where the rotor is. If you don't, you'll have to find TDC on the compression stroke. Not a big deal, but it's easier if you mark it. You then gently pull the old distributor. Try not to turn the oil pump gear, if you do, you'll have to use a long flat head screwdriver & a flashlight to get it right. When you install the new distributor, turn the rotor about 90 degrees counter clockwise to where it needs to point. Gently press it down all of the way. Make sure you get the distributor body close to where it was. After this, you will be ready to hook it up and adjust your timing.
After you have everything back where it needs to be and your timing adjusted, get ready to feel the difference!
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