I have a question for all of you engine guys. It is said that the 60 degree V6 engines are even fireing without the need for a stepped crankshaft. The fireing order for the LFX I plan on putting in my Fiero, for example, is 1-2-3-4-5-6. My original assumption was that the engine would have a cylinder fire every 120 degrees, hence the "even fireing" designation. But then I tried to figure out how that would work and found that it can't if two connecting rods share a journal. Please tell me if I am getting this right. A cylinder fires every 60 degrees of the first revolution, and no cylinders fire during the next revolution. Does that sound right? If so, the engine is not really even fireing, is it?
Interested to hear the following explanations.
Thanks,
Daryl

An inline 6 is one of the smoothest running engines that exists. That is why most big diesels are in line 6's. A v6 is rough running because of what you figured out, a v8 is smoother than a v6 but still not as smooth as an inline 6. You have to go all the way up to a v12 to find a smoother running engine than an inline 6. I don't know anything about inline 8 cylinder engines except when they were popular years ago they had problems with getting fuel evenly distributed resulting in some cylinders running leaner than others. Think of an 8 cyl engine over 5 feet long being fed fuel by one single barrel carburetor in the middle.

Fiero V6 engines are even firing with a power stroke every 120° at the crankshaft.

For reference, here is the crankshaft (before cleaning) that's going into my 60° V6 Fiero:


Each connecting rod has its own crankpin.

[This message has been edited by pmbrunelle (edited 03-11-2018).]

I've always heard that even fire meant the firing order was sequential. An odd fire engine sequence was 1, 2, 3, 4, 6, 5.

quote Originally posted by Daryl M: My original assumption was that the engine would have a cylinder fire every 120 degrees, hence the "even fireing" designation. But then I tried to figure out how that would work and found that it can't if two connecting rods share a journal.

The rods don't share crankshaft journals. They're offset to create an even firing interval.

Even firing means the intervals are even....Odd firing (the 4.3 and early 3.8) are odd firing...the spacing varies...They are basically a V8 missing 2 cylinders. They finally went to split journals so the 3.8 became even-firing; Every 120 degrees....The 60 degree V6 is easier to have natural even firing...

Thanks for the great explanation. Clears things up !

quote Originally posted by Daryl M: Please tell me if I am getting this right. A cylinder fires every 60 degrees of the first revolution, and no cylinders fire during the next revolution. Does that sound right? If so, the engine is not really even fireing, is it?

If this were true, all the plug wires would be on one half of the distributor and none would be on the second.

Note:
Firing order data can lie to you. In books and even "printed" on the engine/intake.
So order to install wires on the cap can be 123456 12345678 but the caps can have other wiring build into them.
Often can't see this even in Factory SM.

I seen several caps that have "circuit board traces" between some external and internal towers buried in the plastic but don't know if Fiero V6 is one.
You have to check the cap w/ Ω meter or carefully destroy an old cap to see real Firing Order for the engine.

------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

quote Originally posted by theogre: Note: Firing order data can lie to you. In books and even "printed" on the engine/intake. So order to install wires on the cap can be 123456 12345678 but the caps can have other wiring build into them. Often can't see this even in Factory SM. I seen several caps that have "circuit board traces" between some external and internal towers buried in the plastic but don't know if Fiero V6 is one. You have to check the cap w/ Ω meter or carefully destroy an old cap to see real Firing Order for the engine.

All the distributor caps I've ever purchased for my V6 Fiero have been the straight-through WYSIWYG (what you see is what you get) type. They didn't have any weird criss-crossed wiring.

If I were to have installed a criss-crossed distributor cap, I'd have found out about it by the poor-running engine.

[This message has been edited by pmbrunelle (edited 03-18-2018).]

quote Originally posted by theogre: I seen several caps that have "circuit board traces" between some external and internal towers buried in the plastic but don't know if Fiero V6 is one.

The 2.8 V6 is not like that. It has a simple "straight through" electrode design.