Different firing order for 302 ci engine

[grumppyoldman]

I've found 2 different firing orders for a 302 ci engine. one's listed for a P code and one for an N code. What's the difference between the two engines? Al

[40cpe]

The roller cam (5.0 HO) engine has the firing order common with the 351.

[rotorwrench]

One might be the Y-block truck engine. What year model 302 are you seeking the proper information for?

[50fordcoupeman]

40 coupe is correct. The early 302's(non HO motors) have a firing order of 15426378 and the HO and 351's have a firing order of 13726548. So there are two different firing orders for the 302 based solely on the generation of the engine. Hope this helps.

[darrell]

im guessing they were using the 351w cam in these engines.a little stronger.

[KULTULZ]

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Here is the best explanation I have come across. This reasoning was also given by FORD in their MUSCLE PARTS BOOK regarding the new (then) 351W-

...with the firing order 1-5-4-2-6-3-7-8 the first main bearing is loaded by two consecutive pistons firing one right after the other with the harmonic balancer right there to take the shock....with the 1-3-7-2-6-5-4-8 this loading is transferred to the rear main journal with has much more support and is balanced by the flywheel/clutch or torque converter assembly.

Now I do not have the specifics to why this arrangement is better, but according to Ford the latter firing order is much easier on the crankshafts.

SOURCE- https://www.stangnet.com/mustang-for...motors.473025/

[TedEaton]

I'll add that when Ford went to using the lightweight crankshafts in the HO 302 engines, there was a propensity for the crankshafts breaking at the first journal. Those lightweight crankshafts used the 50 ounce external imbalance factor on each end instead of the prior 28 ounce factor that you found on the pre 1981 engines. Hence the firing order change. Ted Eaton .

[KULTULZ]

!!! Thank you ted !!!

[grumppyoldman]

Thanks for that info my 302 is an earlier model N code with a firing order 1-5-4-2-6-3-7-8.
The block casting # D1OE-6015 AA above starter means i think it's a 1971 block. Don't know if that's good or bad. Runs good and strong though. Al

[KULTULZ]

D1OE identifies it as a 1971 design casting. You would then need the CASTING DATE CODE to ID the actual model year usage of the block.

Not a thing wrong with it. Good engine.

[JeffB2]

Some guys will use 351W cams in earlier 302's when doing a build to get the later firing order as per the link above.

[grumppyoldman]

I don't know if this is the casting date code, but there is a round raised spot with 1975 cast in a circle on the back bottom of the block in the same area as the block casting. There is another no. which looks like a 3 in the same round raised spot. Al