how many firing sequences for 90* V-8

[A Atwood]

Something is wrong with that ford flat head drawing.

ARN

[lorax]

Something is wrong with that ford flat head drawing.

ARN

Good eye. The firing order is wrong, It should be 15486372
There is no 4 in the order and there are 2 #3. Same firing order as the Y block.

[dave brode]

Thanks Gents, I saw that error last night on the flatty too, while i was making little drawings like lorax posted. I didn't scroll down far enough last night. [smack forehead].

Interesting.

Dave

[USMC_Spike]

Oh nuts.

I thought that was one of the Ford flathead "secrets".

So I was thinking about making a "secret" plug wire
shaped like a vee where the plug connection splits
to two different terminals on the HEI cap.

Something like this lo tech ASCII diagram:
(please ignore the . as the board will remove
the spaces and it won't look right any more.)
not that is looks that good anyway.

3.......3
\....../
..\..../
...\../
....\/
....3

Cheers,

Spike

[dave brode]

Talking normal one bang every 90* cranks;

1. The what seems to be most common "sequence": GM / Mopar / AMC 18436572 [also FE/289 etc ford, same just labeled differently]
2. Flathead ford / 18436572 with 4-7 swap
3. '63 up cadillac / HO ford / LS gm / 18436572 with 4-7 & 2-3 swap.

Look at the Y block ford and the nailhead buick. http://blogs.hotrod.com/msd-ignition-co ... z2ctpYZCRA

It appears that these two are similar, but start on the opposite front corner. Follow the numbers

Nail;

4 3
7 6
5 8
2 1

Y Block:

3 4
6 7
8 5
1 2

So, that makes 5 different sequences that I see. So far...

Dave

Wrong. Y block same as flathead [#2 sequence above].

Dave

[Walter R. Malik]

I remember reading somewhere that Smokey Yunick used a "double fire" firing order and reverse rotation on one of his small Indy V8 engines.
He must have tried it for a reason other than curiosity ... on second thought, maybe that WAS the reasoning.

[A Atwood]

In a 90* V8 with a standard crank, there are exactly 8 different firing order combinations. And no matter how you fire it, two cylinders on the same bank always fire back to back. There is also a 270* break on each bank.
In order to get away from this, the crank must be changed to a flat crank. They also have a completely different exhaust note.
With the standard crank, no matter what the firing order, the exhaust note is the same.
Personally, I love the standard crank "sound"

ARN

I must correct myself here,
Although these are each one of the 8 different firing sequences, they do fall in to a different style of firing order than I explained earlier.
Standard crank, SBC
1-5-7-3-6-8-4-2
1-5-4-2-6-8-7-3
1-5-7-2-6-8-4-3
1-8-4-2-6-5-7-3
With these firing orders, all four cylinders on one bank fire 90* apart, then take a 360* break for the other bank to fire all four.
Interesting.

ARN

[Kevin Johnson]

The first production cross-plane V8 firing order was from Cadillac in the 1924 V-63.

In Ford-speak it was 1-5-4-8-6-3-7-2 (same as the later Ford Flat-head V8 and Y-block).

1924 Cadillac V-63 cross plane V8 firing order.jpg

https://www.gmheritagecenter.com/docs/g ... ac_VVI.pdf

All,

Anyone correct me if I'm wrong;

I notice that Ford guys like to think that GM stole their 351W/"HO" firing order for the LS engines. Note that Cadillac used it in '63. The '63-'67 Caddy is labelled like a 18436572 engine, but order is 1-8-7-2-6-5-4-3 [see 4-7 and 2-3 swapped]. Caddy also used that sequence in '68 up family. They labelled cylinders differently, so it takes some head scratching to see it. Anyone know of an earlier engine using that firing sequence? If so, I'll yield, but if not, said firing order shall hereafter be called the '63 Caddy firing order.

1. The old common "18436572" sequence

2. '63 up caddy, "HO"/351W ford, 18436572 engines with 4-7 / 2-3 swap and LS are same sequence

3. The 18436572 engines with a 4-7 swap are same sequence as Flathead ford.

That's three different sequences. Are there more?

Dave

[Walter R. Malik]

All firing orders must be looked at as running firing orders, or they can look completely different than they really are.
All American V8 firing orders fire the 4 outside cylinder group, then the inside. If it makes you feel better to say its the inside 4 first, then the outside, that's fine, Same damn thing. some times the order cross criss crosses the bank, but its all still, outside 4, inside 4. Or vee a vee. Which ever floats you boat. Every engine.
Look at the Ford mod. 13726548. Looks like an outside corner and then a inside cylinder #3.
But fire the engine off, and it becomes 5481-3726.

Its the starting them ALL with the #1 that makes some of them look odd, but in reality they aren't that odd at all. Give them running patterns, and they all start looking much more alike than you might at first think.

If that chart is correct ... is the number 1 cylinder at the back of the engine on the "Nail Head" Buick...?
Is the numbering on that chart wrong; side to side...? Something is wrong there.

It is physically impossible for number 2 to fire after number 1, (or number 8 after number 7), if it isn't; unless the engine is rotating in reverse direction from normal.

[DaveMcLain]

I remember reading somewhere that Smokey Yunick used a "double fire" firing order and reverse rotation on one of his small Indy V8 engines.
He must have tried it for a reason other than curiosity ... on second thought, maybe that WAS the reasoning.

I think Smokey used reverse rotation to put the torque reaction of the engine so that it loaded the right rear during acceleration instead of the left and vice versa on corner entry to try to gain a handling advantage.

[wyrmrider]

If I remember correctly he did it on a flathead (Hudson?) and turned the rear end upside down trying to load the left rear fro circle track

[John Wallace]

is the number 1 cylinder at the back of the engine on the "Nail Head" Buick...?

No, the bottom of each engine has a 'Front' on it.
(Unless the Nail Head has the distributor in the back of the block)

All are facing the bottom of the pic except the VW.

As for if the numbering is right, I don't know?

(1-2-7-8-etc)

[Truckedup]

The Curtiss OX-5 V8 aircraft engine circa 1917 firing order is 12347856

[Spin Doctor]

A while back on youtube I ran across a clip of late'60s early '70s Trans Am cars coming out of the garage area at one of the historic "race" events and the Camaros and Mustangs all had a nice pop while idling out. The Javelins had a pop going on but they also had a lot of crackling going on in the exhaust note. The 2 small blocks not quite so much. I always wondered if it was related to firing order or valve overlap. The sound was just down right nasty. But in a good way. The best race series ever staged in NA imo

[Kevin Johnson]

A while back on youtube I ran across a clip of late'60s early '70s Trans Am cars coming out of the garage area at one of the historic "race" events and the Camaros and Mustangs all had a nice pop while idling out. The Javelins had a pop going on but they also had a lot of crackling going on in the exhaust note. The 2 small blocks not quite so much. I always wondered if it was related to firing order or valve overlap. The sound was just down right nasty. But in a good way. The best race series ever staged in NA imo

https://www.youtube.com/watch?v=_O3fHeIVfls