Car won't run on HO firing order

K

Keyvon

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Oct 12, 2005

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Dec 22, 2005

#1

• Dec 22, 2005

• #1

I have an 89 GT it only runs on the old school 302 firing order, when I wire it correctly w/351 firing order it barely will run. Does that mean I have a non HO computer? There is a lot of numbers on the computer,which number do I read to find out which one I have?? Is there a site to go check these numbers? Thanks!!

 

timewarped1972

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Jun 17, 2004

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Dec 22, 2005

#2

• Dec 22, 2005

• #2

well the only thing that would effect the firing order would be the camshaft.....as to what cam it has in it.....so it's a 89 HO engine??

 

95 Laser GT Ver

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Dec 22, 2005

#3

• Dec 22, 2005

• #3

I believe it's determined by the cam.

 

timewarped1972

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Dec 22, 2005

#4

• Dec 22, 2005

• #4

yeah and i think the old 302's were 15426378 firing order, ok and i just checked and the newer or HO firing order is 13726548

 

K

Keyvon

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Oct 12, 2005

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Dec 22, 2005

#5

• Dec 22, 2005

• #5

Yes it's an 89 HO motor,Isn't the correct firing order for HO motors the 137something [351 firing order] when I wire it that way it won't run but runs fine on 154something firing order.I thought I heard that means it has a non HO computer.

 

timewarped1972

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Dec 22, 2005

#6

• Dec 22, 2005

• #6

i think that would mean it has a non HO engine
has the engine been swapped with an older one do you know?? it may say HO on the manifold but.......witht hat firing order it would have to be a non HO 302, unless someone took out the roller cam and put in an older cam but, that would not be too likely...

 

S

SmockDoiley

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Jun 14, 2003

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Dec 22, 2005

#7

• Dec 22, 2005

• #7

The computer has nothing to do with the firing order. Your cam and how you order the wires are the only 2 things that dictate what cylinder gets spark. Your computer and engine would run fine off of either kind of cam as long as the firing oder was right. As far as I know all 85 and up GT/LX 5.0s had roller 302's that required the 351 firing order. If yours only runs off of the older flat tappet firing order than someone may have installed a flat tappet cam in it as a cheaper replacement or as a better performing camshaft. Which if that is the case, then I hope they changed the distributor gear to iron and not steel. If the gear wasnt changed then the softer iron gear of the flat tappet cam will get detroyed. I really think you should find out what the deal with this firing order is because you may incur some serious damage if you are running the wrong cam and it wasnt installed correctly.

 

timewarped1972

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#8

• Dec 22, 2005

• #8

the push rods would be different too wouldn't they??? from a roller to a flat tappet??

 

S

SmockDoiley

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#9

• Dec 22, 2005

• #9

I'm thinking its more likely that at some point your motor was changed and maybe thats all they had to use, or the parts store gave them the 79-95 302 special. What would be interesting is to see what the dizzy gear looks like. You could easily pull it out and inspect it. This would help tell you or worry you, depending on what you see. If the firing order is the 351 order, then the gear should be billet steel and smooth looking. If the order is the older flat tappet one, them the gear should look cast and rough. If not, then you should be worried. Most likely you have an older engine swap with a flat tappet cam, and you should make sure the right gear was used because alot of people dont know that.

 

S

SmockDoiley

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#10

• Dec 22, 2005

• #10

Yes, they would be shorter for a roller cam setup because the lifter is longer, but if you can see the pushrods then you can see the lifters so you wouldn't even spend your time on the pushrods.

 

K

Keyvon

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Dec 22, 2005

#11

• Dec 22, 2005

• #11

The block and heads have black paint so I kind of thought it may have been rebuilt,but maybe somebody ruined the block or something and put in whatever they could find,tomorrow I'll pull out the distributer and check the gear.I've put about 2000 miles on it since I got it, do you think the gear would have broke by now??

 

timewarped1972

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Dec 22, 2005

#12

• Dec 22, 2005

• #12

not nessesarily, it doesn't break per say it just wears very fast and gets eaten away......the gear meshes ok it's the material it's made out of......

 

S

SmockDoiley

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#13

• Dec 22, 2005

• #13

Yeah, I didnt mean to scare you. Its just the concept of one harder metal rubbing on a softer metal, you get the idea. It might chip off, or just wear off, its just not good juju. You always have to check these kind of things out when dealing with Ford. They were always changing things around or doing different things and unless you know alot about the subject you can find yourself mixing together the wrong parts. So if the guy who swapped the motor was a chevy mullet guy he'd never even know. It wouldnt surprise me at all. I'm not a complete Ford freak, I just happen to know alot about mustangs since I've tried so many different things with them. I worked at Advanced Auto Parts for 4 months and every employee including the 15 year veteran managers were asking me all questions about Fords because they didn't know anything. If it wasnt GM or Japanese, they had no clue so I always got the weird Ford swap part number questions. They didn't have any Hot Rod or carburetor answers either.

 

Modular2v

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#14

• Dec 22, 2005

• #14

it all depends on the camshaft

 

Maryland Stang

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Aug 21, 2002

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#15

• Dec 22, 2005

• #15

Pull the right side valve cover off and turn the engine over without starting it (pull the coil wire off). Watch for the number 1 cylinder to open the intake valve. Now watch the numbers 2 and 3 intake valves and if the number 3 valve opens before the number 2 then you have a HO cam and visa-versa.

 

Modular2v

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#16

• Dec 22, 2005

• #16

Maryland Stang said:

Pull the right side valve cover off and turn the engine over without starting it (pull the coil wire off). Watch for the number 1 cylinder to open the intake valve. Now watch the numbers 2 and 3 intake valves and if the number 3 valve opens before the number 2 then you have a HO cam and visa-versa.

Click to expand...

thats how i figured mine out! :Word:

 

jrichker

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#17

• Dec 22, 2005

• #17

Check to verify that it is indeed an HO engine. Remove the #1 & #3 spark plugs. Put your finger in #1 spark plug hole. Crank the engine over until you feel compression on #1 cylinder. Slowly turn the engine until the TDC mark and the timing pointer line up. Mark TDC on the balancer with chalk or paint. Put your finger in #3 spark plug hole and crank the engine 90 degrees. You should feel pressure trying to blow past your finger. If you do not feel pressure, repeat the process again. If you feel pressure, it is a HO engine.

No pressure the second time, remove spark plug #5. Put your finger in #1 spark plug hole. Crank the engine over until you feel compression on #1 cylinder. Put your finger in #5 spark plug hole and crank the engine 90 degrees. If you feel pressure now, the engine is not a HO model, no matter what it says on the engine.

Using a small carpenter or machinist square to mark the harmonic balancer off into 90 degree sections may be helpful here.

A 15/16 deep socket & breaker bar or ratchet may be used to turn the engine.

The HO firing order is 1-3-7-2-6-5-4-8.
Non HO firing order is 1-5-4-2-6-3-7-8

 

D

D347643

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#18

• Dec 22, 2005

• #18

302 H.O. is the same as 351 firing order

 

D

Daggar

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#19

• Dec 22, 2005

• #19

If a non-HO cam were installed with a fireing order other than what is normal for a fuel injected HO then wouldn't the fuel injector harness connetors also need to be swapped around so that the injectors open up at the right times and in the correct order?

 

jrichker

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#20

• Dec 22, 2005

• #20

Daggar said:

If a non-HO cam were installed with a fireing order other than what is normal for a fuel injected HO then wouldn't the fuel injector harness connetors also need to be swapped around so that the injectors open up at the right times and in the correct order?

Click to expand...

According to Fordfuelinjection.com, that isn't a workable plan. See http://fordfuelinjection.com/index.php?p=92 for the reasons why.