The two different firing orders questions

[eschaider]

It is possible the original author missed assigning a particular firing order to a particular engine style but the total number of available possible firing orders for Ford is accurate.

While I am unfamiliar with the particular EPEC system you purchased from Ford, virtually every aftermarket system will allow you to specify the firing order of your choice. The only caveat is that you need to have a cam ground to support the firing order and in the case of flat plane crankshafts you also need to have the correct crankshaft.

The most commonly used flat plane crankshaft is both end throws up and both center throws down. However, just to keep us on our toes there is also a up-down-up-down version of the crank that has yet another set of possible firing orders.

You want to achieve two broad goals with your firing order selection. The first is not to produce an intake draw where two adjacent cylinders have sequential charging draws from the intake manifold. In general after the first cylinder has drawn in its charge, the atmosphere in the intake manifold is rarefied and the second cylinder is cheated out of a full intake charge.

To avoid the intake charge cheating effect, you want adjacent firing and therefor charging cylinders to be as physically distant in the intake manifold as possible. You also want to choose firing orders that mitigate, to the extent possible crankshaft oscillations from adjacent power pulses. The more you wind up, then unwind and subsequently wind up your crankshaft again, the more work your crank damper needs to do and the shorter your crankshaft life will be.

Chevrolet and Chrysler frequently use a 18436572 firing order and number the cylinders 1,3,5,7 front to back on the driverside bank and 2,4,6,8 on the passenger side. The driverside cylinder bank always leads the passenger side cylinder bank. On Fords the numbering is 1,2,3,4 front to back on the passenger side bank and 5,6,7,8 down the driverside bank with the passenger side bank always leading the driverside bank.

The Pontiac and Oldsmobile cylinder placement and firing order data mimics the Chrysler / Chevrolet cylinder numbering, placement and firing order. The 215 inch aluminum turbocharged V8 that Olds used in their Turbo Coupes also used the same cylinder placement and firing order. The ever-popular Buick Nail Head V8's from the fifties used a very unique firing order and an equally unique cylinder numbering convention. The firing order was 1,2,7,8,4,5,6,3 and the cylinder numbering was flip flopped from the Chrysler / Chevrolet model with cylinders 1,3,5,7 front to back on the passenger side and cylinders 2,4,6,8 on the driverside. They also lead with the passenger side cylinder bank like Ford does.