Ford firing order for the Y-block = 1-5-4-8-6-3-7-2

Ford firing order for the 260/289/early 302 = 1-5-4-2-6-3-7-8

Ford firing order for the 351W/late 302 = 1-3-7-2-6-5-4-8

Ford firing order for the FE/429/460 = 1-5-4-2-6-3-7-8

SBC firing order converted to Ford # = 1-5-4-2-6-3-7-8

According to some reading I've done on this - the Ford 351W system shows a mathematical and dyno power advantage in a V8- like a couple of percentage points (over the 289/FE version). The big boys in prostock and NASCAR are apparently believers - there are (some) special cams that utilize this scheme available for chebbies and others. Has anyone ever installed this firing order in a Y-block? While the consecutively firing 1 and 2 cylinders makes the Y-block sound we love - a cam with lots of ovelap will do much the same thing. Is there power to be found by making the change? Like more than a couple of percentage points? I'm sure the Y set-up is probably an antique - what do you suppose we are losing? Are there cam blanks available to do this sort of thing (or is it billet only)?

 
 Steve Metzger       Tucson, Arizona

The firing order swap on the scrub engines (and Pro Stock) to which you refer is called the 4X7 swap.  This effectively makes the firing order the same as the Flathead V8 which also happens to be the same as the Y.  It would appear that Henry had it all figured out in the beginning on how to reduce the harmonics on a crankshaft that only had three main bearings.

Lorena, Texas (South of Waco)

OK - I'll bite - the SBC pattern with the "4-7" swap (these are GM cylinder numbers) results in a change from the identical firing pattern of the 289/FE motors (I had to make myself a conversion chart to match it up) - back to the pattern of the Ford flathead and Y motors. Have you ever done this - or any of the Ford FE guys? Would it be an advantage for an FE engine too?

FOMOCO went from the 289/Fe arrangement to the 351W/mod motor arrangement (1-3-7-2-6-5-4-8) - apparently for a mechanical advantage of some sort (and from what I understood its power not harmonics). They didn't go back to the Y/Flattie set-up. What I was reading, was that the GM guys were now going to the later model Ford pattern to get this same mechanical advantage.

When you shift the (new Ford) pattern one place to get the jist of it.....(3-7-2-6-5-4-8-1)..it is firing the cylinders of the two center throws sequentially..3-7 then 2-6. Then it goes odd to the front throw (5) then sequential again 4-8 at the rear throw - then back to the front (1). I think the odd firing favorably alters the shaft harmonics.

Shift the FE pattern around to get the same look....(2-6-3-7-8-1-5-4) ...it fires the center throws .. sequentially 2-6 then 3-7. Then it goes odd to the rear throw (8) sequential front 1-5 and odd to (4) at the rear. I'm having trouble understanding what I know about this..... either one should have about the same effect. Out of the possible four - there are three sequential crank throws where power from a firing cylinder is directly compressing an adjacent cylinder. This seems to be directly equal to the 351W/mod motor set-up.  

The Y/ flattie set-up is sequential at the front throw 1-5 then sequential at the rear 4-8 - then odd four times in a row (6) - (3) - (7) - (2) on the center throws. I think this is a disadvantage to both of the other patterns where a firing cylinder is directly compressing the common throw. Wrong?  

Found a mistake for sure 3-7 in the Y-block is sequential - so there are three there too.....

 
 Steve Metzger       Tucson, Arizona

After knawing on this a while - and not finding a good way to analyze the harmonics of the various arrangements - I tried looking at the firing orders based on deflection (torsional wind-up at the main bearings) and carried to the flywheel. It may not be exactly correct, but deflection energy is what's going to give the harmonics power - the power to fatigue and maybe break a crankshaft.

There are many engines built with (and these are using Ford's cylinder location numbers) the 1-5-4-2-6-3-7-8 firing order. This includes small and big chebbies, chrysler products, and Ford FE, 289, 460, Pontiac - dunno how many more.

The Ford Y-block and flathead engines use the 1-5-4-8-6-3-7-2 firing order - and if you do the "4-7 swap" (GM numbers here) Ted mentioned, on a chebbie - you can get this same arrangement.

Every cylinder that fires - is compressing another cylinder - which is a direct (but variable) subtraction. The relative location of these two cylinders determines where the resulting torsional deflections are resolved in the crankshaft. The maximum possible deflection value is the same for both orders (the worst case loading) - but the "mean" - average - in two revolutions is less by a significant amount with the Y/flathead scheme.

The late Ford firing scheme is 1-3-7-2-6-5-4-8 and it has an identical max/mean deflection value to the FE/289/460 set-up ..............I'm still chewing on that one.  

 
 Steve Metzger       Tucson, Arizona

Wow, go, Steve, go.

It's all I can do to rewire my setup now and not get the wires crossed.

Numbers make brain hurt.

think I'll have a beer and let you guys figure this out and tell me how it's going to be.

       A  L  A  N   F  R  A  K  E  S   ~  Tulsa, OK    

I am with bird55.  I am already having a beer.  I am getting into this reciprocal engine building late.  I spent most of my adult life flying and working on turbine engines in military helicopters.  They ony have one firing order.  On, and hope it stays lit.  Cheers to you all.

Jan  Urbanczyk  Major USMC Ret.

                                                                 Bowie Maryland

hurts my head too - I'm just trying to cruise out the day......hopefully there are a couple of Dos Equis still hanging around in the fridge

 
 Steve Metzger       Tucson, Arizona

Steve, The front two rod throws are often drilled for lightness. And often the rear rod throw is not drilled. I assume this is because of the extra needed material to help resist bending and twisting as the torque is transmitted through the crank to the flywheel. I suspect that you could do a little drilling of the rear throw without losing much of its stiffness.



I wonder if the mass/inertia of the flywheel and its close proximity to the rear throw is why they chose to allow the 4 and 8 cylinder to be the odd ones out, and allowing all the others to be paired up.



Boy, I hadn't spent any time looking at the Y firing order. That sequential 4,6,8 firing on one side would account for the 'harley' sound. Pretty cool, but it would militate for some try-y headers. (Tri-y's on a Y)

Best regards,



Paul Menten

Meridian, Idaho

Steve: This is an interesting subject & there was also a recent article in one of Hot Rods specialty issues on the subject. I find it interesting & went out of my way to jazz my Chebie loving coffee friend, about how his favorite engine runs better with the Flat Head/ Y-Block firing order. ( Needless to say, Hot Rod didn't mention the Y-Block in their article!)  However, I have to compliment you on your perservering on the subject. I can't get my head around it, anywhere near the level you do.    

Paul