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Wierd firing order...?

utahmike

Full Member
Joined
Jan 5, 2002
Messages
233
Loc.
Spanish Fork
I have a question...today i printed (checker auto) the firing order for various ford 8 cyl. motors. I compared it to my ford factory manuals and both were the same. I noticed the 302 firing order being, 1-5-4-2-6-3-7-8 counter clockwise and i checked my 302, it was ordered the same as the 351, 1-3-7-2-6-5-4-8 counter clockwise. so i changed it to the 302 order and it ran rough i changed it back to the 351 order and it runs smooth. what gives i know my engine is a 302. so why the 351 firing order? an old post said something about a different cam? if so please explain? if not the cam what and why? TIA ;D

-Mike-
 

broncnaz

Bronco Guru
Joined
May 22, 2003
Messages
24,341
you could have a factory 302 HO motor if its not the orginal or the camshaft has been changed some cams are ground with the 351/HO firing order and when installed must be wired as 351's or you get the rough running engine you describe. any 302/351cam will work in either engine as long as the firing order matchs the cam grind. Hope this helps.
 

wildbill

Old Bronco Guy
Joined
Jun 29, 2001
Messages
6,885
;D ;D ;D Ford claims that the 351W needed the different firing order so it would not run hot. They say if you run a 289/302 cam the motor can run hot and they also changed it in the HP 302. But it will with eather cam as long as the fireing order is to the cam in the motor .%) %) %) Bill :cool: %) :p
 
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utahmike

utahmike

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so this may sound uneducated but, are either of these good? and is the HO motor better the same or worse than a 351 cam. what advantage is a 351 cam or the ho motor compared to stock. this motor was rebuilt about 18k ago i bought it from the P.O. he had it done at a local shop and really didnt know much about it he just had his bronco nut father in law take care of the details. do i have more hp or tourqe than a stock?talk to me...
 

BoltBuster

Bronco Guru
Joined
Jun 5, 2002
Messages
2,051
Something you may also consider when using a 302 cam in a 351W is the duration height of the lobes. I think they are lower than a stock 351W cam and will not open the valves long enough for the full amount of fuel to make peak performance.

Firing order for 351s is 1-3-7-2-6-5-4-8. But, if an early 302/289 cam is used, it's 1-5-4-2-6-3-7-8.

Summit firing order chart:
http://www.summitracing.com/tech/charts_guides/firing_order/tz_02charts_firing.htm#
 
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utahmike

utahmike

Full Member
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Jan 5, 2002
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Bolt Buster...Dude did you read the whole post? we already know the firing order for what engine and which cam. i have a 302 w/ a 351 cam...possibly. Not a 351 w/ a 302 cam. ;) the question is if i have this, is it good, how would i know if it is a 351 cam or a 302 HO, and what makes it HO? ;D
 

iwlbcnu

Bronco Guru
Joined
Nov 1, 2001
Messages
3,341
it just shows you have a non stock 302 cam that is running the 351 order.
I was told the reason for the firing order change was to lesson the strain on the bearings from 2 consectutive cylinders firing.
 

Skuzzlebutt

PhD, Dr. of Broncology
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May 26, 2001
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What year is the 302? In the '80s Ford first changed the order on the HOs but later changed the order on all 302s.
 

Broncobowsher

Total hack
Joined
Jun 4, 2002
Messages
34,834
Skuzzlebutt said:
What year is the 302? In the '80s Ford first changed the order on the HOs but later changed the order on all 302s.

What?? I have never seen a stock, non-HO 302 with the HO firing order. The only one I am not sure of is the Explorer 5.0. I should know, I work on them. Since they don't have a distributor, I don't worry about it. I would consider the Explorer to be an HO since it has all the good parts (heads, GT40 intake, etc)

The HO started back in '82 by putting a marine cam in the 302. They didn't even bother putting a 4V carb on until about '84. Roller cam came in '85.
 

trailpsycho

Bronco Guru
Joined
Dec 11, 2003
Messages
4,856
Utah-

My guess would be that the Bronco nut father in law went ahead and put in a HO cam maybe a E303, B303 or comparable cam from a good manufacturer in since it was a rebuild. Maybe even a 5.0 HO motor or a "imitation rebuild" neither of which would be a bad thing. Dont worry about it. If he had it built, and is a "nut" you probably have a great motor. There should be no difference in performance just based on the firing order, the difference will come in the grind of the cam(separation, duration of the lobes). If you dont have that info, then there is no way to tell you anything about what you have. Do you like the way that it runs? Then keep the 5.0 HO firing order and drive it like its saturday night. One other thing that might help is to check your heads, see if you can find their casting or if they are aftermarket...if they are not the original heads, they may have swapped the whole block. If it was rebuilt they may have redone (ported/valve job) the heads to a more performance type set up, again, not a bad thing. Again, obviously, they put in a newer style (referring to 5.0 HO/351W firing order), this is not bad. Is it not runnning well or are you just trying to become "personal" with your goods?
 

iwlbcnu

Bronco Guru
Joined
Nov 1, 2001
Messages
3,341
You are right. The Ex is HO firing order.
Also, not all Mustang GT's in 85 were roller, the auto's were still flat tappet.
 

Skuzzlebutt

PhD, Dr. of Broncology
Joined
May 26, 2001
Messages
4,393
Loc.
Honeymoon Bay
Broncobowsher said:
What?? I have never seen a stock, non-HO 302 with the HO firing order. The only one I am not sure of is the Explorer 5.0. I should know, I work on them. Since they don't have a distributor, I don't worry about it. I would consider the Explorer to be an HO since it has all the good parts (heads, GT40 intake, etc)

The HO started back in '82 by putting a marine cam in the 302. They didn't even bother putting a 4V carb on until about '84. Roller cam came in '85.

I was under the impression that by the end of the run, all 302s had the newer (351) firing order.
 
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