1,3,4,2.

[Mixer]

Does anyone know of another A7 firing order other than 1.3.4.2. and if so, why?

[Bob Olive]

I know very little about firing orders other than 1-3-4-2 seems to have been the most common among British manufacturers. I think I am right that the firing order of a side-valve Riley 11/40 tourer of 1927 which I owned a few years ago was (from memory)
2-4-1-3, and I believe that for the ubiquitous and very successful Riley 9 was 1-2-4-3. There will be others far better informed than me...
Presumably though it was all at the behest of the engine designer, I can't see that any one would have been smoother than another, at least not in a 'four'.

[steve anderson]

3 4 2 1 /  4 2 1 3 /  2 1 3 4 , or make a cam with the order changed around , same result  ??

[Pearls not a Singer]

1930s Standards (as made in Coventry) labelled the rearmost cylinder as no 1

[Bob Culver]

1243 used by Ford.

[Tony Press]

Anticlockwise versus clockwise distributor rotation ?

[Renaud]

But 1342 and 1243 are the same engine when you number from the front or from the back.

[Hugh Barnes]

Indeed, Riley 9 is 1,2,4,3... Which I have to remember when I have my head under a different bonnet...

[Colin Morgan]

Presumably there are only these two options - 1,3,4,2 and 1,2,4,3 with our shape of crankshaft? (As the next one that fires has to be 180 degrees out from the last.)

[Bob Culver]

True Renaud. Fire outward or inward whichever direction you number the cyls. Are you in lockdown perchance?
Whatever happened to the traditional questions like Why doesnt my dynamo charge?
I dunno what the factors are. With separate manifold runs to each cyl as moderns the mixture distribution should not be affected.