TOPIC: Ozone dist. cap mod

Here's how to modify a distributor cap to do 2 things. This idea is from Mike Holler, MPG Mike on the Net, a wonderful guy and Gadgetman too!

If your engine has a distributor, chances are the cap has a vent, or a replacement cap exists w/ a vent. The vent allows the ozone that is generated from the high voltage jumping from the rotor to inside cap contacts, to escape. Also it prevents a vacuum condition inside the cap if there's a vacuum leak past the dist. shaft. Ozone (O3) is formed from ionization of oxygen in air from hi-voltage discharges in the air. The sweet smell in the air during a thunderstorm is Ozone.
Normal Oxygen molecule is O2. Ozone, O3, is highly reactive and will corrode the cap contacts and rotor tip. Ozone will also react w/ gas molecules in the intake tract, helping to break the hydrocarbons down. By adding a small diameter plastic vacuum line, plentiful in junkyards in the emission controls on mid-70's-up engines, we can direct this small amount of generated Ozone to work for us in our dist. equipped engines. This also extends service life of the cap/rotor by actively removing this reactive Oxygen species. This can only be done on a vented cap, DON'T do this on an un-vented cap. Vacuum inside the cap will cause spark scatter!

Get a piece of the hard plastic small dia. vacuum line. Select a drill bit a bit smaller in dia. than the line. Opposite the vent, look inside the cap, you want the hole to be outboard of the arc of the rotor tip's path. Mark location and drill from outside, I used a small punch to lightly mark the spot. I roughen the surrounding plastic and end of the plastic tubing w/ sandpaper, this promoted adhesion of epoxy to hold the line securely. Insert the line so it is flush or just barely protruding inside the cap, be sure the rotor tip can't strike it. Use hi-temp resistant glue or epoxy on outside to secure it permanently.

Get some rubber vacuum hose that fits the hard plastic line, you may find it on the donor vehicle. In the pictures I show the hard tubing, rubber vacuum hose, and some red vinyl hose I found at Home Depot in the plumbing/Irrigation aisle next to the plastic fittings. The red tubing is sold as small engine fuel line in 3 diameters. I cut the hard tubing a few inches off from the cap to suit the installation, press the hose on the tubing end, then run the rubber or vinyl hose to carb. or TB vacuum source. It should go into a central point of the intake plenum so as to be equally distributed to all cylinders. You can add a control valve like aquarium or drip irrigation valve to regulate the amount of flow and reduce the resulting small vac. leak. I just splice it in a convienient place in the hose to adjust it. Home Depot has the small drip irrigation valves too.

Result: the distributor cap and rotor will last longer, and we tap a free source of Ozone to assist w/ more complete combustion. Nothing magical w/ the red hose, I just showed it as another type of small dia. tubing. On my Subie the Weber DGEV has a venturi vac. port that's where my Ozone cap hose goes. Older cars w/ fuel inject. and a distributor sometimes have vacuum ports on the TB. Or just use a centrally located man. vac. port, and adjust the flow w/ the irrigation valve.

Tracy G

Just posting here to get this up on forum again, cheers Kiwi Mike!

Tracy G

That was an interesting read Tracy ! and the pictures even better too ! Come to think of it I don't think my Rotor Cap is vented but I will have to look when I get back home as I didn't take the car on Holiday this time haha ! I will get back to you on this subject

Cheers !

I have also been experimenting with this though using a plate ozone generator that is rated at 3 gr/min. I am getting more horsepower in my chevy 350, still need more driving to look at mpg differences.

that's quite interesting, Ken, can you share any pics and details of your Ozone setup? I've been curious about using Ozone, haven't done more than the dist cap mod yet. A power increase is good, can you quantify it? thanks, Happy New Year!

Tracy G