Firing Order.....Help!

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Mar 24, 2009 | 06:45 PM

Hillcapper

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From: Mooresville, NC

Firing Order.....Help!

Need some help on firing order. I am building a 5.0 (purchased 1994 engine from junk yard) to replace the 4.9 in my 94 F150 2WD. I'm doing a warmed over build, port, polish and cam. My donor vehicle is a 1990 F150 5.0 which I am getting computer (SD), engine wiring harness, engine perches and distributor etc. Here is where I need help.

What is the firing order of the 1990 5.0?

I have installed a Crane 444211 (firing order is 13726548) in my 5.0 build.

If the 1990 computer is the 15426378 firing order is that a problem?

I am guessing I can change wire order on the distributor correct? What about injectors firing? Is SD sequential fire or bank fire?

Thanks for the continued help

Mar 24, 2009 | 06:48 PM

EPNCSU2006

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From: Concord, NC

The 90 was batch injected speed density. Just change the plug wire order at the distributor and you should be good to go.

Mar 24, 2009 | 07:00 PM

Hillcapper

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From: Mooresville, NC

Eric, help me understand batch injected. If thats bank injected then wouldnt the fact that the computer is firing on one bank (say #3) and the distributor is firing #5 on the other bank but with no fuel?

Mar 25, 2009 | 04:58 AM

EPNCSU2006

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From: Concord, NC

The injector grouping is 1,4,5,8 together and 2,3,6,7 as the second batch. There will be fuel ready to get sucked into the cylinder, the only difference would be the time between when the fuel is injected and when the intake valve opens. At speed, this really shouldn't be noticeable because of how fast these events occur. Think about cycle time at 2500 rpm: .024 seconds per revolution means the fuel isn't doing a whole lot of waiting around.

Mar 25, 2009 | 07:17 AM

Hillcapper

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From: Mooresville, NC

When you put it in those terms I see what you mean. So I'll just change the firing order at the distributor.

Thanks

Mar 25, 2009 | 10:53 AM

Conanski

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From: Ottawa, Ontario

And just so you don't think you are the first one to do this, both the 5.0 and 5.8 SD motors have the injectors wired exactly the same, and these motors have different plug firing orders from the factory.