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4.3L and an Impco 425...

Discussion in 'The Garage' started by sled_dog, Aug 16, 2006.

  1. sled_dog

    sled_dog 1 ton status

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    Think a 425 is too much for a stock(to be modded) 4.3L? Seriouslly considering grabbing a junkyard 4.3L for my S10 and already have a brand new 425 for my propane setup. future plans would be bored out and cammed or maybe turbo(in which case a 425 would make plenty of sense).
     
  2. HarryH3

    HarryH3 1 ton status Author

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    Sled, search around over at www.austink5.com There are a few guys on there that drive bunsen burners. ;)
     
  3. Citizen Rider

    Citizen Rider 1/2 ton status

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    haha, yea, quite a few guys know alot about propane over there.
     
  4. neverendingproject

    neverendingproject 1/2 ton status

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    I dont know about propane setups, but I know a properly modded 4.3 can put out some insane numbers for a 6 cylinder.
     
  5. mrk5

    mrk5 The Sticker Guy Moderator Vendor GMOTM Winner Author

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    I've been checking out propane kits on gotpropane.com and I saw this:

    Looks to me like you'd be okay.
     
  6. 85mudblazin

    85mudblazin 1/2 ton status

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    If the 425 is to much then I have a 225 that would work for ya. A 225 is to big for a 22re so I am assuming it would be good on jeep type motors. So the 4.3l might fall into that slot.
     
  7. Blazr77400

    Blazr77400 1/2 ton status

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    This will tell what you want to know.
    CID * RPM / 3456 * 0.85 = CFM required

    425 flows 460 cfm max

    262.5 * 7000 / 3456* 0.85 = 452 cfm required
    carb size formula LINK
    So you will be good to over 7000 rpm
    Over carbing it should just make it burn rich. Shouldnt hurt power output. It just wont burn all of the propane.

    On my truck it was either be under carbed or over carbed with the 425's. I went with 2 just to make sure there was enough power.

    Here are some other good propane links.
    http://franzh.home.texas.net/engine.html
    http://www.dualcurve.com/home.htm
    http://www.patooyee.com/ (Go to the technical section and click on Propane)
    http://www.wps.com/LPG/index.html#INDEX
    www.propaneguy.com (where I got all my stuff)
     
  8. sled_dog

    sled_dog 1 ton status

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    Yeah thats part of what the problem is. I'm going to finish my 383. Big issue for me is my 383 is the same boat as your 400. Its either going to be under or overcarbed. Oh well. I am just not looking forward to the cost of another 425, 2 Model E regulators, 2 carbs for their bases, dual carb intake, and the linkage/lines to make everything work. Oh well, it ought to run like a raped ape when all is said and done.
     
  9. mrk5

    mrk5 The Sticker Guy Moderator Vendor GMOTM Winner Author

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    gotpropane.com sells a kit for "big blocks and hot small blocks" that flows better than the Impco 425.
     
  10. sled_dog

    sled_dog 1 ton status

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    The X450 mixer. Try finding a new one. I'm buying all new components for my system(no messing with rebuilding or hoping things arne't worn out). THey however do not flow THAT much more air than the 425 does. Forget what the comparison specs are. Besides which, $1100??? I'll have less than that into my dual carb setup with tanks! And all BRAND NEW Impco stuff.
     
  11. 73k10sub

    73k10sub 1/2 ton status

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    Where to buy parts?

    Can you let us in on where you are buying your new parts? It looks like I fall in with some of you on whether the 425 would be enough - 350 bored .030 over running a mild cam and currently topped with a Q-jet.

    Thnaks, Ronnie
     
  12. sled_dog

    sled_dog 1 ton status

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    Ebay man. Bought from a couple places so far. All I have at the moment is one 8 gallon fuel tank, my 425, and a VFF30 Lockoff. Lockoff and Mixer are brand new.
     

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