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Old 06-02-2009, 03:20 PM   #1 (permalink)
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Default Does NEW vs OLD 302 firing order really matter?

Taken directly from compcams website:

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Originally Posted by CompCams
Firing Order, Small Block & SVO
This is one of the most common questions asked by our Ford customers. The firing order for the early 221-302 engines and the early 5.0 engines is 1-5-4-2-6-3-7-8. This is the firing order for all prefix “31” cams and is the standard replacement cam for all early engines. The later 5.0 engine and all 351 engines are designed to use the 1-3-7-2-6-5-4-8 firing order. This is the firing order for all prefix “35” cams, and cams ordered for these engines should use this prefix. Other than the firing order, the cams are identical. By changing the spark plug wiring at the distributor these cams can be interchanged.
My cam grind is a # "31".

I just have had some recent discussions with a friend about this as well. Does it change, enhance, dampen anything using the new order vs. the old one ?

Just curious. Thanks
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Old 06-02-2009, 03:22 PM   #2 (permalink)
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I think it has to do with preventing crossfire of wires and a more even distribution of the pressure on the crank.
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Old 06-02-2009, 03:26 PM   #3 (permalink)
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Jeremy-
I used the '351' cam build on my Reed. It helps even distribution and better 'balance' through the core of the engine.

There is definitely a benefit to the different firing order for higher revving/HP/Torque engines. I think newer 302 Builds use it because the technology proved it to be a better firing order than the original 60s specs.

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Old 06-02-2009, 03:29 PM   #4 (permalink)
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The "1-3" firing order was to reduce the load on #1 main bearing....
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Old 06-02-2009, 03:37 PM   #5 (permalink)
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Quote:
Originally Posted by AzPete
I think it has to do with preventing crossfire of wires and a more even distribution of the pressure on the crank.
I don't think that affects that Pete. If you look, old vs. new; the old has 7&8 firing & the new has 5&6 firing adjacent to each other.

So I would assume the possibility of inductive crossfire would still be there if those 2 wires were to closely parallel each other. Much as the old 7 & 8 scenario.
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Old 06-02-2009, 03:42 PM   #6 (permalink)
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Thanks Snell.

Quote:
Originally Posted by Hemikiller
The "1-3" firing order was to reduce the load on #1 main bearing....
And that's pretty much the only + ?

Oh and thank you again for that sport mirror washer! it was greatly appreciated.
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Old 06-02-2009, 03:46 PM   #7 (permalink)
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Damn, missed that all together.....
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Old 06-02-2009, 03:56 PM   #8 (permalink)
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Of course the new firing order places 4 & 8 firing in sequence, loading the rear main instead of the front...

I'm sure if you're at 99.9%, looking for that extra .1%, there's an advantage... but for common folk, it's 6 of one, a half-dozen of the other. Nothing worth over-analyzing, IMO.
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Old 06-02-2009, 04:02 PM   #9 (permalink)
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I found this:

"
The reason for this difference in the 1:1 STD-vs-HO is all in the camshaft timing, lift, and duration. Cylinders 5 and 4 , and cylinders 3 and 7 fire really close together as matched pairs. When the H.O. version was cooked up, a number of customers complained of a rough idle. Even in the heyday of factory hot-rods, a lot of folks wanted smooth idle.

Ford engineers quickly worked this out, and found that swapping cylinders 5-4 with 3-7 got rid of this, thus eliminating a customer satisfaction problem.

No overall performance difference can be felt with either wiring order. No kidding.

edit: oh by the way, if you look at V-8 firing orders overall you will find that Ford's cylinders physically fire in the same order as GM and Chrysler's, Ford just numbers the cylinders differently that's all."


BTW, my cam has the 351 F.O., Dema Elgin suggested it for a "race" engine.
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Old 06-02-2009, 05:12 PM   #10 (permalink)
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So you are running the 1-3-7-2-6-5-4-8 firing order Mark ?
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Old 06-02-2009, 05:45 PM   #11 (permalink)
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Quote:
Originally Posted by 70_Fastback
So you are running the 1-3-7-2-6-5-4-8 firing order Mark ?

Teeeeeeeen- fo
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Old 06-02-2009, 06:51 PM   #12 (permalink)
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Cool; thanks.
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