[AT] Rationale for firing orders

[Roger Welsch]

Hey, I'm getting a college education in engineering without paying the
tuition!  Wish I'd have thought of this with three kids!

Rog


----- Original Message ----- 
From: "Larry D. Goss" <rlgoss at evansville.net>
To: "'Antique tractor email discussion group'"
<at at lists.antique-tractor.com>
Sent: Monday, March 22, 2004 7:20 PM
Subject: RE: [AT] Rationale for firing orders


> Dudley does a good job of describing what's going on in the engine, Rog.
> When it comes to 1-2-4-3 vs. 1-3-4-2 firing order, I remember being told
> by the professor in the Internal Combustion Engine course that used to
> be part of the mechanical engineering curriculum at Purdue, that
> designers tried to even out the stresses in the crank and camshaft by
> spacing the firing along the line of cylinders as far apart as possible.
> The firing order probably doesn't make much difference on an in-line
> four, but it does make a difference when you get into 6-, 8-, and larger
> engines.
>
> This information and 50 cents will buy you a cup of senior coffee at
> your local McDonalds.  :-)
>
> Larry
>
> -----Original Message-----
> From: at-bounces at lists.antique-tractor.com
> [mailto:at-bounces at lists.antique-tractor.com] On Behalf Of Dudley Rupert
> Sent: Monday, March 22, 2004 4:22 PM
> To: Antique tractor email discussion group
> Subject: RE: [AT] Rationale for firing orders
>
> 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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