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Propane Problems!

Discussion in 'The Garage' started by tom4, Aug 30, 2006.

  1. tom4

    tom4 Registered Member

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    I just installed propane on my chevy 350. I used the 450 mixer. It’s running like crap! I tried timing it but that didn’t really help. It has no power. Can anyone who installed propane on there truck help me? I'm 30 min north of Dallas if anyone is close by.
     
  2. Russell

    Russell LB7 Tahoe Status Premium Member GMOTM Winner

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    Its common to loose a bit of power when switching to propane, but it shouldn't be enough to make the engine a dog... Maybe try putting a larger venturi into the carb and see if it helps?
     
  3. Citizen Rider

    Citizen Rider 1/2 ton status

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    Have you adjusted the mixture? Like a carb, you got to adjust it to run right.

    is everything mounted properly?

    You give no details as to what you have done to try and solve this and what the problems are other than "no power". People here could give you a broad band of what your problems could be, but without details...its not going to help.
     
  4. tom4

    tom4 Registered Member

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    Everything is mounted properly. I have not tuned the mixer yet because I'm really not sure how to do it yet. Im sure its simple but I didnt want to mess anything up.

    Other than my engine being a complete dog I only have one other problem: my truck doesn’t want to shift. I'm sure this is just a vacuum problem because the vacuum source changed with the new mixer.

    Also I know that you can lose power when switching to propane but I got the 450 mixer which is supposed to flow more than the 425.
     
  5. 74 chev

    74 chev 1/2 ton status

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    new mixer or old?
    dual fuel or straight porpane?
     
  6. MattK

    MattK 1/2 ton status

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    brand new mixer, straight propane.
     
  7. sled_dog

    sled_dog 1 ton status

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    what regulator are you using? You can't use a Impco regulator/vaporizer with a X450 mixer. The 425 and 450 use two different styles of fueling, though I can't remember what the differences are.

    Going to a 450 mixer won't gain you the power back that you are going to lose. Propane has less BTUs as it is, there is just less energy potential there.
     
  8. 85mudblazin

    85mudblazin 1/2 ton status

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    You arnt going to notice the power difference when switching to propane. As for the 450 mixer, the only time that it is going to shine over a 425 is in the higher RPM ranges. With a truck I doubt you are going over 4-5K.
     
  9. Disciples Performance

    Disciples Performance 1/2 ton status

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    i run propane on my 400SBC and to tell u the truth its really hard to tune them, so im sending mine to a shop 75$, and they time then engine and tune the mixer for me and itll run perfect everytime. the timing should be 12 deg adv Mech and at 3000 RPM 32 Deg Adv Mech. if that helps u a bit
     
  10. sled_dog

    sled_dog 1 ton status

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    You can't give a static "timing should be" for every engine with propane. Compression, ignition system, and a few other factors will play into what will work best.

    Just as you can't say "all 350s running on 87 octane should run 4* BTDC"
     
  11. Disciples Performance

    Disciples Performance 1/2 ton status

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    that was just what i was told to run on my 400 from the guys that tune these things all day long so i just thought id say what i did and see if it helps i mean u can always change your timing around
     
  12. AussieK5

    AussieK5 1/2 ton status

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    32 deg total is a litttle on the high side for my likes, I've always run 28-30 total by no later than 2500. If you tow or romp it hard you could run into trouble with any more. Thats 10 initial at the crank and 9 at the dizzy. Its worked for every SBC combo I ever run over the last decade or so. Its safe and recomended by more than one reference text.

    That said, any timing setting for gas will let a propane engine idle and run relatively smoothly...you just dont belt the piss out of it.

    Unless your stuffing up the timing when you set it I'd be looking elsewhere for your problem. If your going to run propane drop a few bucks on amazon for a good reference text and save yourself a load heartache.
     

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