3406b turn up

Discussion in 'Trucks [ Eighteen Wheelers ]' started by 92pete, Sep 9, 2009.

  1. 92pete

    92pete Bobtail Member

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    Have a stock 425cat b model, Whats some opinions about turning it up, Everyone local tells me to turn the screws, but I'm a little hasty. Right now I can only hit 1000* pyro temp, pre turbo. Can hit about 23psi turbo. Am I going to run into problems If I turn it up to around 500hp? It doesn't smoke right now,would it if I turned it up?? Need some second opinions:biggrin_25520:
     
  2. 05chopper

    05chopper Light Load Member

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    Sounds like you have low power have you had it on a dyno lately to check out what H/P or does it run the same as when you got it? Putting the rack screws in your pocket will fix some of your low power but I do not advise it. I would check for air leaks in the air to air,check timing advance unit for bad weights plus pin timing the unit first.If it runs really good for a 425 then you can do other mods to get you where you want to be.One major question for me would be the clutch and trany taking on this much power could be a problem later down the road. More fuel=more air= list goes on.
     
  3. Les2

    Les2 Road Train Member

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    You might want to re-read his post, I know I had to read it twice. He's talking 1000* before the turbo with 23lbs of boost. Now if he was talking post turbo temp being 1000* with only 23lbs of boost you'd be dead on.

    I don't think he's really having low power....its just stock 425 power and he wants more...:biggrin_255:
     
  4. 92pete

    92pete Bobtail Member

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    Correct les2,
    It runs just fine and egt's are low, but I haul cattle and hay in NM and Co, I am just looking for a little more go in the go pedel. But I don't want to decrease the life of my kitty either.

    The dieselgarage.com was very helpful. I think that I'll turn the screws out 3 truns. I think that should put me around 500hp(correct me if wrong). If I don't like it I can always put it back.
     
  5. Les2

    Les2 Road Train Member

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    Yep, you got it! Just make sure you turn both screws out the same amount of turns.

    You can also go into the AFRC and turn that screw in a cpl turns. Advance your timing and timing advance may be a good idea also but you may want to have someone else do that. Make sure you keep an eye on your temps, water and turbo!

    Edit*** One other thing...you'll love it, but until you get used to runnning it with more power your mpg's will most likely suck! Once you get the hang of it they will most likely be better than when it was stock.
     
  6. 05chopper

    05chopper Light Load Member

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    You need to check timing advance unit and also advance the timing easy to do! Find and pin TDC at the flywheel.Remove the 9/16 plug in the middle of the fuel pump there will be a notch down inside the plug hole.Cat uses a pin to set timing here you do not need the pin. Now Remove the timing advance cover it has a long point to it.Loosen the outer timing advance bolts this will let you roll the timing advance unit up to bump and rotate the fuel pump and set the timing.Rotate the unit up with a small bar prying on the outer t/adv bolt till you get a bump on the camshaft notch apox 3/16 lip at the bottom of the plug hole. Torq the t/adv unit to 35 foot pounds then roll engine over to tdc again recheck fuel pump notch then tighten down timing advance unit crisscross pattern to 35-foot pounds.If the 3/16 notch is still there you are good to go if not redo it.Replace the cover gasket.This setting works great at higher altitude and you will be happy with this advance setting.Remember to remove the 3/8 long bolt from the flywheel.
     
    Flyer Thanks this.
  7. 05chopper

    05chopper Light Load Member

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    Backing out the fuel screws without advancing the timing will give you a slow response. Its kind of a guessing game backing out the screws without a dial indicator to measure rack travel.Did you check your diaphragm in the AIR FUEL RATIOCONTROL?
     
    Last edited: Sep 10, 2009
    Flyer Thanks this.
  8. 92pete

    92pete Bobtail Member

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    no I haven't checked the diaphram but I will when I mess with it this weekend.
    How do you find TDC on this thing???
     
  9. Les2

    Les2 Road Train Member

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    On the passenger side of the motor in the bellhousing there will be a hole. You'll need a pin or bolt thats small enough to fit in there. I took a bunge and ran it from a crossmember, over the bolt and down to something below the bolt to keep tension on it so when you hit the hole the bolt goes in. There is also a plug on the side of the fuel pump, take it out and get a pin or bolt that will fit that. If the pin drops in both holes at the same time, your timing is dead on, not advanced any.

    If the timing hasn't been messed with for a while, it most likely will be off or de-advanced.
     
  10. 1989 Pete

    1989 Pete <strong>"Pine Tree Eater"</strong>

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    Sounds like a job for Bruce and the boys at Pits Pwer
     
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