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Define "good working injector"

Discussion in 'The Garage' started by Kiqman, Mar 13, 2006.

  1. Kiqman

    Kiqman 1/2 ton status

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    1989 350 TBI. What type of spray pattern should I see? It seems like a bit of the gas is splashing out of the ports. I think maybe the mist should be finer? Sometimes I even think they're dripping. Obviously I can't see them except when the truck is idling in park. Are they worth rebuilding or do you just buy new?
     
  2. 1985_K5_Silverado

    1985_K5_Silverado 1/2 ton status

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    I saw in your profile that you have an aftermarket cam. What make and grind/profile number is that cam, and are you using the standard ECM or did you have it reprogrammed for the new cam?
     
  3. R72K5

    R72K5 Banned

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    well there shouldnt be dripping or splashing, it should be spraying, finer mist the better

    they probably need rebuilt, or modified if you dont have stock engine


    good luck
     
  4. Kiqman

    Kiqman 1/2 ton status

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    249-12-235-2 Xtreme 4x4 X4254H Hydraulic Flat Tappet Comp Cam
    Lift: .447''/.462''
    Duration: 254°/262°
    RPM Range: 1000-5200

    I put this cam in. I've done nothing to the ECM. Runs like crap until it goes into closed loop.
     
  5. Kiqman

    Kiqman 1/2 ton status

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    New heads are GM HP 64cc
     
  6. 1985_K5_Silverado

    1985_K5_Silverado 1/2 ton status

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    You know them already, but for everyone reading this thread, here are the specs on that cam (copied from Summit's site):

    [FONT=Arial, Helvetica, sans-serif]Part Number [/FONT][FONT=Arial, Helvetica, sans-serif]12-235-2[/FONT][FONT=Arial, Helvetica, sans-serif]
    [/FONT][FONT=Arial, Helvetica, sans-serif]Grind Number [/FONT][FONT=Arial, Helvetica, sans-serif]CS X4 254H-11[/FONT]
    [FONT=Arial, Helvetica, sans-serif]Cam Style:Hydraulic flat tappet[/FONT]
    [FONT=Arial, Helvetica, sans-serif]Basic Operating RPM Range:1,000-5,200 RPM[/FONT]
    [FONT=Arial, Helvetica, sans-serif]Intake Duration at 050 inch Lift:210[/FONT]
    [FONT=Arial, Helvetica, sans-serif]Exhaust Duration at 050 inch Lift:218[/FONT]
    [FONT=Arial, Helvetica, sans-serif]Duration at 050 inch Lift:210 int./218 exh.[/FONT]
    [FONT=Arial, Helvetica, sans-serif]Advertised Intake Duration:254[/FONT]
    [FONT=Arial, Helvetica, sans-serif]Advertised Exhaust Duration:262[/FONT]
    [FONT=Arial, Helvetica, sans-serif]Advertised Duration:254 int./262 exh.Intake [/FONT]
    [FONT=Arial, Helvetica, sans-serif]Valve Lift with Factory Rocker Arm Ratio:0.447 int./0.462 exh. lift[/FONT]
    [FONT=Arial, Helvetica, sans-serif]Lobe Separation (degrees):111[/FONT]
    [FONT=Arial, Helvetica, sans-serif]Intake Valve Lash:0.000 in.[/FONT]
    [FONT=Arial, Helvetica, sans-serif]Exhaust Valve Lash:0.000 in.[/FONT]
    [FONT=Arial, Helvetica, sans-serif]Computer Controlled Compatible:No [/FONT]

    That "No" most likely indicates that it isn't likely to work flawlessly with the factory stock computer module programming, which doesn't necessarily mean that yours can't be reprogged to make it all run just fine.

    CompCams (try their 800 number, 800-999-0853 I think) should be able to let you know either way, but from those cam stats, it looks like it wouldn't be much of a chip fiddle for someone that has the equipment. Maybe the guys at www.pcmforless.com (they've done some C4 Vette stuff for a few people I know) or a similar outfit.
     
  7. randy88k5

    randy88k5 1/2 ton status

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    If you think the fuel might be coming from the injectors themselves, check the o-rings. I had one go bad, and it let too much fuel in and ran pretty bad. I could see the fuel dripping out with my timing light.
     
  8. Kiqman

    Kiqman 1/2 ton status

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    Comp Cams are the ones that recommended this cam to me in the first place. I told them 1989 350 TBI with aftermarket heads and headers. The guy at the time said this cam was within the tolerances of my ECM's ability. This morning I call comp cams and the tech tells me that I MIGHT have some vaccum issues - which I think explains why it runs like hell when the choke has shut off but the motor hasn't gone into closed loop yet. You go to the damn website and it says the cam will work. The "Computer Controlled Compatible" cams are hardly any better than stock for towing and trailing? So now how the hell do I "chip" my 1989 ECM to work better with this cam? I didn't think you could do anything to an ECM this old. Right now I'm just dealing with sluggish conditions on warm-up. I'm afraid if I start messing with the ECM I'm going to have problems everywhere! What the hell does computer controlled compatible mean anyway?
     

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