Firing order on V8

Does somebody could explain me why they are different firing orders on V8. I noticed that 302 were different than 351. With also a different crossing on the exhaust pipe.
The sound is also different. That meens cam shafts are timed differently also ?
Fred from France
(please use simple words my english is so bad !)

I really don't think there is any difference. Ford numbers the cylinders like this:
(looking down on the top of the engine installed in the car)

front (water pump goes here)
5 1
6 2
7 3
8 4
rear (flywheel goes here)

The two firing orders are:
1-5-4-2-6-3-7-8 (289/early 302)
1-3-7-2-6-5-4-8 (351/later 302)

Now look what happens if we number the cylinders differently:

front
8 4
7 3
6 2
5 1
rear

1-3-7-2-6-5-4-8 on the original engine is 4-2-6-3-7-8-1-5 on this engine. Move the numbers around so that 1 is first and you get 1-5-4-2-6-3-7-8

One firing order is just a mirror image of the other.

Exhaust crossover should not be any different. The two middle cylinders on each side of the engine are crossed over. This means that with either firing order, cylinders 1, 4, 6, and 7 feed one collector and 2, 3, 5, and 8 feed the other. This is so that you get an even series of exhaust pulses in each header. Looking at the two firing orders again and taking every other cylinder, we get:
1-4-6-7 & 5-2-3-8 for the 289 firing order
1-7-6-4 & 3-2-5-8 for the 351 firing order
Same set of cylinders no matter which firing order you use, and the two sets match the lists above (which I listed in increasing numerical order).

Just taking the exhaust bit a bit further, if you ensure that when you cross over the primary pipes, the way they enter the collector "rifles" the gases. This is what GTD did and it makes the car a bit quieter and more efficient on getting rid of exhaust fumes = power gain? However I beleive that this was not done on some original cars! I stand to be corrected.

Malcolm

According to Ford performance the change in the firing order to 1-3-7-2-6-5-4-8 (351w and 302HO/5.0L)was "to revise main bearing loads" ?

Clayton

I also read that the firing order was changed on the 5.0 engine so that cyl 7 and 8 didn't fire in line. the later is 4 and then 8 as to prevent cross fire.
VIC

Mk-IV exhaust crossover.

7 and 8 don't fire sequentially, but adjacent cylinders 5 and 6 do (though not necessarily in that order). The plug wires that go to 5 & 6 are shorter, and that might make some slight difference in avoiding crossfire...

Are there two FREDS on the forum? one in Brussels and one in France, or are they one and the same, just moving countries? I know the Belgium Fred! whos the French Fred?Frank

I think we are 2 Fred for my part i am living near Versailles in France.
Something funny i bought my 40 in Belgium 6 years ago to a guy named Johan ...

the firing order on my car is
1-3-7-2-6-5-4-8
the sound of the engine is very hard not as smooth as 302 are. I saw different guys at LE MANS CLASSIC from Enthousiast club
they all got the crossover on the exhaust pipe, not me on my 351 SVO HO.
Should i change the firing order and the pipes to gain power or not ?
something very strange also i haven't got vaccum firing advance.

Sorry Fred, I got confused between the Freds, good job my names Frank