V8 Firing Orders
V8 Firing Orders
(OP)
Out of curiosity I have been "collecting" V8 firing orders. So far I have found 5 unique firing orders for a conventional 90 deg bank angle cruciform crank V8. For clarity, cylinder numbering is from the front of the engine to the back, so odds are on one bank, evens on the other.
They, along with their twins (cylinders numbered back to front), Ford numbering system equivalent, and a partial list of engines that use them are:
Original Twin Ford
12784563 15436872 15486372 Ford Flathead Lincoln Flathead Ford Y-block Lincoln OHV Buick Nailhead
18547236 14527638 18364527
18736542 12634578 18654273 caddy flathead Olds OHV
18726543 12734568 15426378 MEL wedgeblock Ford FE
18436572 15634278 13726548 Caddy OHV Desoto Firedome Chevy smallblock Pontiac Mopar B AMC 1st & 2nd gen Olds 2nd gen Porsche 928
They, along with their twins (cylinders numbered back to front), Ford numbering system equivalent, and a partial list of engines that use them are:
Original Twin Ford
12784563 15436872 15486372 Ford Flathead Lincoln Flathead Ford Y-block Lincoln OHV Buick Nailhead
18547236 14527638 18364527
18736542 12634578 18654273 caddy flathead Olds OHV
18726543 12734568 15426378 MEL wedgeblock Ford FE
18436572 15634278 13726548 Caddy OHV Desoto Firedome Chevy smallblock Pontiac Mopar B AMC 1st & 2nd gen Olds 2nd gen Porsche 928





RE: V8 Firing Orders
RE: V8 Firing Orders
RE: V8 Firing Orders
RE: V8 Firing Orders
RE: V8 Firing Orders
RE: V8 Firing Orders
RE: V8 Firing Orders
http://w
Franz
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RE: V8 Firing Orders
Cylinders 5/7 and 2/4 both have the intake ports grouped as pairs with only a divider wall between the ports so it does not alter the geometry of the 90 deg in firing order separated ports.
I have never seen a credible explanation as to how this helps anything other than cam makers profits.
One noticeable thing about the original SBC firing order is that it not only has most names in the list, it also has all the most performance oriented names in its list.
I wonder what firing order Jaguar, BMW, MB, Audi, Ferrari, Rover, Aston Martin, Toyota and Nissan use, that is after they are all converted to the Chev cylinder numbering system. That is by doing the obvious and starting at the big end journal closest to the snout as 1 and counting along in sequence to end at 8 closest to the flywheel.
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RE: V8 Firing Orders
RE: V8 Firing Orders
RE: V8 Firing Orders
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RE: V8 Firing Orders
I don't recall what reasons were given for changing the firing order. It could have been torsional vibrations, or main bearing loads as someone else said.
The flathead Ford mentioned above is probably the V8 60. It was just a smaller version of the regular flathead, made around 1937. The 60 may have been the horsepower. The larger engine had around 100. They were so cute you wanted to cuddle them.
RE: V8 Firing Orders
1A, 1B, 4A, 2A, 2B, 3A, 3B, 4B (from a Jaguar technical guide I downloaded from somewhere off the internet long ago)
I ASSume this is starting at the front of the engine (oddly enough, the technical guide does not specify). Converting to odd numbered cylinders on one bank and even on the other, this yields:
12734568
Bob
P.S. - someone check my work to make sure I converted it properly - it's been that kind of day.
RE: V8 Firing Orders
Either way, the same two cylinders fire one after the other, 68 for one numbering system and 57 for the other.
RE: V8 Firing Orders
RE: V8 Firing Orders
Seed Reverse Mirror Mirror-Rev Ford
12784563 15436872 18736542 12634578 15486372
18547236 14527638 14527638 18547236 18364527
18726543 12734568 18436572 15634278 18654273
It's interesting that the second one is the same when mirrored & when reversed, and it's also interesting that I found no examples of an engine using this one.
RE: V8 Firing Orders
RE: V8 Firing Orders
Seed Reverse Mirror Mirror-Rev Ford
12784563 15436872 18736542 12634578 15486372
18547236 14527638 14527638 18547236 18364527
18726543 12734568 18436572 15634278 15426378
RE: V8 Firing Orders
That looks pretty.
But I guess a bit of space between them would be good!
12784563
18547236
18726543
I just drew the firing orders.
This PC will be off most of the time, and when it is on, it is via a dial up connection with the whole village going through some multiplexing concentrator that effectively makes the modem useless. If the pictures don't show, you aren't missing much.
RE: V8 Firing Orders
RE: V8 Firing Orders
12734568, reading left to right
It just looks weird to me when you get two cylinders on the same bank firing one after another, like 73 and 68 in the example above.
RE: V8 Firing Orders
RE: V8 Firing Orders
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RE: V8 Firing Orders
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RE: V8 Firing Orders
Norm
RE: V8 Firing Orders
www.retallickeng.com.au
Was told it couldnt be done, so
i went and did it!
RE: V8 Firing Orders
It is a translation into conventional numbering of Greg's posted Bosch 18364527 order.
RE: V8 Firing Orders
RE: V8 Firing Orders
this is the firing order, 1L-3R-3L-4R-4L-2R-2L-1R
Not sure on cylinder numbering.
www.retallickeng.com.au
Was told it couldnt be done, so
i went and did it!
RE: V8 Firing Orders
RE: V8 Firing Orders
The 4/7 swap simply moves the adjacent firing cylinders to the front of the engine, thus they get first shot at the water pump and it makes it easier to jet the motor when carbs are used. Obviously, the 4/7 swap is not as critical if a reverse flow setup is employed.
John
RE: V8 Firing Orders
The holes in the deck are designed to restrict flow enough to stop high flow due to shortcutting of flow at the front and stagnant water water at the back.
This would suggest the coldest cylinder but the hottest head at the front. This would suggest 4/7 swap has no advantage nor disadvantage, except to line the pockets of cam grinders and to cause a non standard firing order that may lead to incorrect wiring of spark plug leads.
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RE: V8 Firing Orders
I would suggest you stop suggesting and start measuring!
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RE: V8 Firing Orders
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RE: V8 Firing Orders
Also, in a pair of cylinders, if one goes lean and therefore possibly hot, the other goes rich and therefore possibly cold, so we get one hotter and one colder, so how does colder water help the cold cylinder.
If the hot cylinder were to go into detonation, I could see your point, but I have never seen a detonation problem cured by the 4/7 swap.
I have seen detonation or chamber overheating problems cured by directing water flow to hot spots by changing water inlet or exit points or by changing the size of water passages in the deck. I have more often seen them cured by simple jet or nozzle changes.
I have only ever measured individual chamber temperatures by spark plug reading as that indicates the temperature inside the chamber, not way out in the water jacket.
If I was having trouble controlling temperature around a particular cylinder, I would try to correct the water flow rather than change firing order.
On a SBC I put my effort in this regard into getting more water between 3/5 and 4/6 as that is where exhaust heat causes gaskets to blow with std exhaust valve layout.
I fix charge robbing problems in the manifold, not the camshaft.
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RE: V8 Firing Orders
Look, its no big deal....people have been doing it for 30 years or more and it does not cost extra if the cam grinder has masters with the 4/7 lobe setup. I admit, I have not kept up with the latest technology and don't know what they are doing now.......and I certainly no longer use carbs.
You stated you could not find a plausible reason for the 4/7 swap and I simply gave you one that worked in the day.
John
RE: V8 Firing Orders
1-8-7-2-6-5-4-3 - LS7
1-3-7-2-6-5-4-8 - 4.6/5.4
Coincidence?
John
RE: V8 Firing Orders
Larry
RE: V8 Firing Orders
RE: V8 Firing Orders
Their reason may have been they did not know better in that day and age.
It may have been constraints with room.
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