[AT] Rationale for firing orders

[Steve W.]

The firing order is to even out the power pulses. In a four stroke
engine with 4 cylinders you set it up so that one piston is always
producing power.
In your example starting with No.1 firing at TDC and No2 is on BDC the
start of compression, No3 would be at TDC on exhaust and No 4 would be
at BDC on the intake stroke. This assumes a flat crank with throws at
180 degrees.
JDs make that unique sound because they actually coast 360 degrees
between each power impulse.
That is also the reason why Harleys make a unique sound, and why they
shake your teeth out when they run.
The firing order and power impulses are also the reason why an Inline
engine or a 180 degree V are the smoothest running engines, Power pulses
come evenly spaced. The next best are the 90 degree V engines.

Steve Williams
Near Cooperstown NY


----- Original Message ----- 
From: "Roger Welsch" <captneb at micrord.com>
To: <at at lists.antique-tractor.com>
Sent: Monday, March 22, 2004 12:09 PM
Subject: [AT] Rationale for firing orders


> 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
>
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