[AT] Rationale for firing orders

[Dudley Rupert]

Roger:

You ask "why is the firing order 1-2-4-3 and not 1-2-3-4.
I think the answer is in the way the crank is laid out -

If the cranks in the AC's are like those in the Farmall M then
1)  Pistons 1 & 4 are always in the same position in their respective
cylinders and likewise for pistons 2 & 3 and
2)  Pistons 1 & 4 are 180 degrees out of phase with respect to pistons 2 &
3.
    Said another way, when pistons 1&4 are all the way up 2&3 are all the
way down.

This means then that when 1&4 are at TDC 2&3 are at BDC - so let's say #1
fires this time.
180 degrees later 2&3 are at TDC while 1&4 are now at BDC - so let's say #2
fires this time.
180 degrees later 1&4 are back at TDC while 2&3 are back at BDC - so, since
#1 has already fired, we're left with #4
180 degrees later 2&3 are back at TDC while 1&4 are back at BDC - so, since
#2 has already fired, we're left with #3.

FWIW The firing order for the Farmall M is 1-3-4-2.  This simply means that
in the second firing step above AC fires #2 while Farmall fires #3.  I am
not aware of any advantage of firing one way or the other -

Dudley
Snohomish, Washington

-----Original Message-----
From: at-bounces at lists.antique-tractor.com
[mailto:at-bounces at lists.antique-tractor.com]On Behalf Of Robinson
Sent: Monday, March 22, 2004 10:48 AM
To: Antique tractor email discussion group
Subject: Re: [AT] Rationale for firing orders


Roger Welsch wrote:

> Can someone help me with a brief and simple explanation of why a motor's
> firing order wouldn't always be one-two-three-four?  My Allis WCs are
> one-two-four-three but I have no idea why....  I love to kid my in-laws
that
> they've always prefered John Deere Bs because they can remember the firing
> order.....
>
> Roger
>



	I don't know about that Rog, I am not sure if the firing order on my
1948 A is 1-2 or 2-1.    ;-)


--



"farmer"

Just when I was getting used to yesterday, along came today.


Francis Robinson
Central Indiana USA
robinson at svs.net


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