odd or even fire?

[billyballer]

Can someone tell me if the cologne 2.8 v6 is an odd or even fire motor?
I'm trying to track down an MSD 6A box and they have a separate part number for odd-fire V6s. I did a google search and found info hinting that it was odd and other info hinting that it was even fire.

thanks

-Bill

 

[Spowerback]

These sell for 169$ + shipping.
http://www.msdignition.com/product.aspx?id=5811

 

[billyballer]

Again even fire or odd fire is what I need to know.

-Bill

 

[Hotrodlincoln]

What's the difference?

 

[billyballer]

On an even fire motor the cam lobes on the distributor that trigger the points are spaced evenly so the cylinders fire at even intervals. On and odd fire motor the lobes aren't evenly spaced, they are at different intervals. I just don't have access to the motor until the weekend so I don't have a way to pull my dizzy and check. I figured someone on this forum would know.

-Bill

 

[Hotrodlincoln]

Ahh. I can look on both of mine later. One is duraspark the other is TFI.

A friend of mine bought a parts car that has an MSD 6A in it. Says he's not gonna use it so I'm thinking if putting it in my truck. I guess I would have been in trouble if I had hooked it up and it was the wrong one.

 

[billyballer]

I did more reading and it seems that rods are paired up on single journals on the crankshaft of an odd fire, so instead of six individual rod journals there are 3 wide journals that are home to two rods a piece.

 

[Hotrodlincoln]

As far as I can tell it's even fire. I couldn't see too well in the dark (flashlight kinda died on me) but they looked pretty even to me. Also did some looking on MSDs website and they have a vehicle selection menu. They list the 6AL #6420 for the 2.8, which according to their manual is the even fire model.

 

[Hotrodlincoln]

This is a picture of the Duraspark vacuum advance disty in my 84. Would you call this "Even" fire?

I dunno if that helps you any if your disty has points.

 

[litleblue]

Odd fire refers to a special Buick engine that was manufactured in the 60 and 70's. Essently the GM engineering team removed 2 cylinders from a v8 engine making it a v6. The result was a distributor that looked like it should be mounted on a v8 however it was missing 2 spark plug connectors and the triggering rotor in the distributor that was missing 2 teeth. Another significant differance was the engine didn't have stepped crankshaft. Cylinders 1 and 3, 2 and 4, 3 and 6, shared the same crankshaft journals. The way the engine ran was 123_567_ the spaces being pauses where the 4th and 8th cylinders should have been. The result was a engine that has a little better milage. The Jeep heads love this engine since it has a significant amount of torque. The reason being is when GM manufactured the engine they had to increase the mass of the flywheel beyond what was normally used for a similar sized engine. The larger flywheel would absorb the oddfiring balance problems with the engine and give the impression the engine had a lot of torque. After a few years GM installed a stepped crank and made the engine an even firing unit. A lot of shade tree mechanics really screwed up these engines by installing an even firing distributor on the engine. The engine would run poorley and backfire quite a bit. Essently the ignition timing would only be correct for the 1st and 3rd cylinder the other 4 cylinders would be severly advanced or retarded. The result was usually burned pistons from preignition if the engine was operated for an extended time.
The little ford duraspark distributor you have taken a photo of came from an even firing engine. The engine that distributor came out of was a straight six or a V 6 with a stepped crank. The European v6 installed in Rangers was an even firing unit with a stepped crank.

 

[Hotrodlincoln]

Interesting. So that's probably why they say odd firing 6 cylinder engines in the manual.
Thanks for the history lesson. Now that I know the 6AL will work, I just need to order some spiral core plug wires and I can hook this thing up. Always have wanted to try one of these things, but never felt like spending the coin to get one just to "experiment".