Firing Order 1–5–4–2–6–3–7–8 vs 1-3-7-2-6-5-4-8

2997 Views 9 Replies 5 Participants Last post by baylensmanfl, Jul 17, 2018

lwhitcomb

Discussion Starter · Jul 15, 2018

I just want to make sure I understand this...the difference between the two firing orders is CAM dependent, and the same CRANK work with BOTH firing orders???

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Correct.

The idea was to smooth out crank harmonics and fire adjacent cylinders at a different time for better fuel distribution. Power gains are phenomenally small. It's kind of a "Well, I guess maybe it's better? At least it's not worse, and it didn't cost us anything?" situation.

But yes, this is 100% dependent on the cam, and the crank doesn't care. Ignition has to be set up to match the cam, of course, or you'll have it firing on the exhaust stroke of a couple pistons.

This was one of the things that set apart the HO motors from 'regular' 5.0 engines, along with forged pistons and higher compression.

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GT'sGT

· #3 · Jul 15, 2018

OEM firing order is the best. It was designed and engineered with all possibilities of firing order, not just 2 and will work the best.

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Grimbrand

· #4 · Jul 15, 2018

Well, that's easy to say. But WHICH OEM firing order, and why? That's what I wanted to know. Both work fine. The HO/351 order is very marginally better, but probably not noticeably so.

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lwhitcomb

Discussion Starter · #5 · Jul 16, 2018

Thanks! That answers my question.

I'm putting a 5.0 from a '95 F150 in my 67 so I can keep driving it while I rebuild the original 289. I saw people talking about firing orders and cams, but I had no idea that cranks were the same (order)...I was just curious. (I DO understand that you can't just swap the cranks back and forth without making adjustments to the cylinder skirts on the 289...but I have no intention of swapping the cranks...I just heard cam, cam, cam...and no one was talking about the crank so I wanted to make sure I understood)(I'm the worlds oldest noob and I really enjoy learning)

Thanks, again, for the replies. I appreciate it!

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Grimbrand

· #6 · Jul 16, 2018

Believe it or not, the 289/302/5.0 hardware is basically *all* interchangeable. No difference in pistons, skirts, etc. The old 289 had a slightly longer rod because at full extension, the crank holds the piston on a 302 a little higher up in the hole. You can put a 289 crank in an '89 5.0, if you really wanted to, or vice versa.

The ONLY major differences were with the Boss 302 which had 4 bolt mains and some other odd stuff, the counterweight balance thing (28.5 oz vs 50 oz imbalance) which changed over in what, '86? And then of course, the change to EFI which also happened in the mid 80s.

Even a lot of parts from the earlier 221 and 260 motors will interchange, though there is no good reason to. Those poor things didn't make much torque, and physically, they are the same size on the outside. Plus those blocks have 5 bolt bellhousing patterns.

You can actually increase stroke on a 289/302/5.0 all the way to about 347 cubic inches (3.4" stroke!) and even some of those don't have to have any notches put in - although on many, a small relief has to be ground into the bottom of a cylinder or to just to ensure that the rod bolts don't make contact.

Always happy to share some of the hard-won knowledge I've come by, and glad to have you here on AFM!

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silver69

· #7 · Jul 17, 2018

And the later blocks had a 1 piece rear main seal and a much better one piece pan gasket.

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GT'sGT

· #8 · Jul 17, 2018

Grimbrand said:
Believe it or not, the 289/302/5.0 hardware is basically *all* interchangeable. No difference in pistons, skirts, etc. The old 289 had a slightly longer rod because at full extension, the crank holds the piston on a 302 a little higher up in the hole. You can put a 289 crank in an '89 5.0, if you really wanted to, or vice versa.

The ONLY major differences were with the Boss 302 which had 4 bolt mains and some other odd stuff, the counterweight balance thing (28.5 oz vs 50 oz imbalance) which changed over in what, '86? And then of course, the change to EFI which also happened in the mid 80s.

Even a lot of parts from the earlier 221 and 260 motors will interchange, though there is no good reason to. Those poor things didn't make much torque, and physically, they are the same size on the outside. Plus those blocks have 5 bolt bellhousing patterns.

You can actually increase stroke on a 289/302/5.0 all the way to about 347 cubic inches (3.4" stroke!) and even some of those don't have to have any notches put in - although on many, a small relief has to be ground into the bottom of a cylinder or to just to ensure that the rod bolts don't make contact.

Always happy to share some of the hard-won knowledge I've come by, and glad to have you here on AFM!

LOL He only asked about the firing order.

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Grimbrand

· #9 · Jul 17, 2018

He did point out why he was asking though, so a bit more information about parts interchangeability probably wasn't unwelcome.

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baylensmanfl

· #10 · Jul 17, 2018

Actually according to the ford litarture at the time. The 351w firing order was there totake some of the load off the front bearing support. No other reason! Yes you can swap the cams brom a 302 into a 351w but you'd have to change the firing order.

My favorite cam still for a small block running a carb is the alliance "hipo" it is very similar to the 271hp grind but desinged to run hydralic lifters.

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