302 Computer on a 408?

Discussion in 'Fox 5.0 Mustang Tech' started by hoopty5.0, Mar 13, 2011.

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  1. I was told that I cannot run my 302 EFI computer/harness on my 408 "because the firing order is different" by a Ford "Expert". Is this true? I hadnt even thought about the 302 stuff not working on the 351. I'd rather not spend $4,000 on a F.A.S.T. Kit. Thanks guys.

    - Collin
  2. It won't work without some serious tuning.
  3. can you run a 302 cam to change the firing order or is it more based on the ecu not keeping the A/F ratio?
  4. More of the latter
  5. The 302 HO and 351w firing order is the same, so firing order doesn't matter.

    You can use it, but will probably need a tweecer or some good tuning like Stykthyn said.
  6. Well as long as I dont have to shell out 4 grand for an aftermarket system, tuning was always in the plans. What do most people do that run efi 408s?

    Or, will a 351w ecu plug in to the 302 harness? Would I need a new engine harness also? I looked at SMOKEDYA's build thread but didnt see anything specific. I'll keep looking around.

    Trying not to run a carb. I have to pass emissions for 3 more years until the car qualifies as an antique vehicle.
  7. You can run the stock computer just fine.
    It's done all the time without tuning equipment or programs.

    a 351 based engine is really just a bigger 302.
  8. You must be the "expert" he talked to :nono:
    As far as tunning run the stock A9L computer and harness and use A SCT chip all will be good.Also when you order your cam get it to use the current 5.0 fireing order and once again all is good.I went threw this exact same thing when doing my 351 based motor! BUT if you use the old firing order you will need to repin the harness!So much easier to get the cam for the current 5.0 HO order.peace

  9. One other thing tho as far as emisions.....you might not pass if you dont have carbed approved stuff,and emisions equiptment?Running a 408 might be hard to get to pass,maybe pass with the 302 then replace it with the 408 afterwards?????? Just take the chip out with the 302 and then reinstall it with the 408.REMEMBER DONT REMOVE THE CHIP WITH POWER TO THE CAR.peace

  10. ^^^^I can vouch for this. When the HO 302 was put out there they used 351w firing order for some strange reason.

    origional 289/302 was:15426378

    351w and ho 302 was:13726548

    camshafts for ho302 and 351w are same same. dunnit.
  11. A 408 or 410 with a 302 HO computer has been done and vristang (Jason) in the 5.0 Tuning forum has one that he drives on a regular basis. PM him or visit the 5.0 Tuning forum for some idea and help.
  12. Thanks guys. Y'all saved me alot of worries!
  13. I never claim to be an expert and I've personally never seen a 351 based stroker run WITHOUT a tune. Hence my reply. I will gladly as always defer to those more knowledgeable.
  14. It seems like getting a 408 to run well without a tune would seriously depend on using a really good "calibrated" MAF meter and correct injectors. Otherwise, you'll probably be SOL without tuning. Of course, there are lots of guys who FUBAR the whole MAF meter/injector thing on otherwise very mild 302s and they still don't run right without tuning.
  15. can i take a 302 out of my 1970 mustang and replace it with one out of a 1989 bronco without running into a lot of problems
  16. Aftermarket ECU's are not anywhere near 4k.

    You can get a complete big stuff setup for way under 2500 and Megasquirt 3 for 600.

    Ill be going with megasquirt this summer.
  17. Only if you give me the mustang.
  18. Not quite sure what you're trying to say there...?
  19. While at my buddies shop today i asked what they do for the 351 computer situation.
    They said they do nothing, it isn't necessary and if you use the right parts and assemble it correctly there should be no problems.

    As always though a good Mass air meter and the right injectors are needed, but if you guys don't know that already and you are working on 351 based engines in a fox, somewhere along the lines you didn't pay good attention.
    OonDeanisS likes this.
  20. Sorry i could sworn i seen you talked to an expert?But that was hoopty5.0 tht said that.My bad! :nonono: :nice:

    Matching MAF and injectors will still possibly need a chip tho :shrug:I'm asking NOT questioning you two.I used a LMAF and 42's on my N/A 351,but then again it wasent a 408 either. peace

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