Odd Or Even

Is there a quick and easy way to tell if a HEI dist. is odd or even fire?

 

Copied from the internet --Somebody, in the know, will have to tell you if the following is correct & helpful--

Identifying Odd VS Even-Fire Distributors
Before installing or re-curving the HEI for the Jeepster, let's make sure you have the correct one. Odd and Even Fire distributors look similar, but operate differently. Use the wrong one, it will run, but not like it should. 3 cylinders will be timed wrong.

The parts are interchangeable, and some rebuilders have mixed up the parts, so you can't go by the parts numbers alone, physically look!

Look at the inside of the distributor, it's easy to tell the difference. The Odd Fire has 3 points mounted on the shaft that rotate with the shaft - (called the Pole Piece, it looks like a 3 pointed star.)

The Even fire has 6 points on the shaft, it looks like a 6 pointed star.

The Odd Fire has 6 unevenly spaced stationary tips (called the Stator) that point toward the inside, or Pole Piece.

The Even Fire has 6 points also, but are evenly spaced around the inside.

That's what determines when the module lets the coil fire. The coil will fire every time the Pole Piece tips line up with the Stator tips. You can see why they call Odd Fires odd, they are.

Odd and Even caps are interchangeable, there is lots of confusion about which cap to use. When in doubt, look at a parts book for the right cap. Most of the ones I've seen for odd fires have 4 posts in line, then a space, then 2 posts, then another space. They look like a V-8 cap with 2 missing towers. Don't let that deceive you, that is not how it fires, 4 and 2. The inside of the cap has tangs that "steer" the terminals. I've also seen an odd fire cap with equally spaced terminals. Using an odd fire cap on an even fire distributor does not make it an odd fire distributor, it just makes it a "nothing." It will run, but not like it should.

 

I remember the 3-points vs. 6-points. There was an online article on how to convert an even-fire distributor. The main difference is in the position of the pickup coils. The odd-fire has two pickup coils separated by 45 degrees, and the 3 points on the reluctor wheel are separated by 120 degrees. This gives a trigger at 45-75-45-75-45-75. The even fire has a single pickup coil (?) and 6 points separated by 60 degress, giving 60-60-60-60-60-60. You should be able to tell by looking under the cap.

 

There are some good photos here: HEI's EXPOSED

 

Just found this site and it's what I needed.

 

I found this video and it explains the odd fire hei pretty well. Hope it helps someone!

 

There was also a semi odd Chevy v6 200 and 229 that look like they work on Chevy 4.3s but don't.