97 suburban plug gap .040 or .060 ?

Discussion in 'Performance & Fuel' started by bsharles, Aug 7, 2009.

  1. bsharles

    bsharles New Member

    I have a 1997 suburban 5.7 350, I have heard that for better gas mileage I should gap the plugs at .040 the specs call for .060...will this .040 help with fuel mileage or have I mistaken what they were saying? I dont have a cold air intake on it yet as I haven't had the truck very long and social security checks just dont go very far so I have to do little things at a time..I also heard that I should flip the air filter cover up side down..is this like on the old v-8's when you could flip over the air filter covers? And will it help on fuel mileage or am I peein in the wind..I have thought about a chip upgrade but will have to save for those kind of things...any help I would greatly appreciate .Bobby
  2. 2COR517

    2COR517 Epic Member 5+ Years 1000 Posts

    Use Genuine AC Delco plugs gapped at .040". You might want to run some Seafoam through the intake before you do the plugs. As for the air cleaner, just leave it stock. It doesn't have the conventional style filter you are used to. A CAI is a waste of money in my opinion, especially if you're going after fuel economy. Do a complete tuneup first. Air and fuel filter, PCV Valve, Clean the throttle body and Idle Air Control, Seafoam the intake and the tank, O2 sensors, AC Delco plugs, cap, rotor. NAPA premium wires.

    If you have money left over, go for a custom tune. It will give you much better results than the CAI, for about the same money.

    Here's a link detailing the Seafoam process and TB cleanup.

  3. bsharles

    bsharles New Member

    Ac delco or splitfire?

    I bought splitfire plugs [copper classic] so should I take them back and get the ac delco? do they work better? and what is SEAFOAM? I haven't heard of it but will look it up in just a minute, I'll clean the TB and replace the pcv and air filter also, I have the 5.7 vortec 350 so it doesn't have a distributor or rotor, And where do I find the Idle Air Control ? sorry for so many questions but I haven't work on a vehicle in years except for the motorcycle I wrecked lol
  4. Z71_guy

    Z71_guy Epic Member 5+ Years 1000 Posts

    im almost positive your truck has a distributor, and you will be fine with those plugs AC delco is good be not the best just another spark plug
  5. bsharles

    bsharles New Member

    distributor cap found

    I went and looked and they have it hid there way in the back behind the vortec box, good thing it wasn't a snake. well looks like there are a couple more parts to add to the tune up now..I said I haven't worked on trucks in awhile but never thought I would miss something as important as the distributor cap..must be the old age..or do I blame it on bad eye sight..thanks I never would have looked for it again,, well hopefully I would have seen it when I do the plugs Saturday afternoon, Should I go ahead and try the .040 gap with these plugs or stay with the .060 ? :sign0017:
    Last edited: Aug 7, 2009
  6. 2COR517

    2COR517 Epic Member 5+ Years 1000 Posts

    Uh, yeah. .040"

    New plug wires, Napa premium should be on your list also.

    The Idle Air Control is in the throttle body.
  7. azdrtdog

    azdrtdog Epic Member 5+ Years 100 Posts

    dont go with the mutli electrode plugs they are known to cause a misfire code in vortech motors i learned that from a set of bosch and i bought a cheap cap at checker it was bad and cross fired in the cap. just a couple things i've learned an come across over the years

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