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87 350 tbi timing

Discussion in 'Performance & Fuel' started by realtree87, Dec 7, 2012.

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  1. realtree87

    realtree87 New Member

    I have a stock 350 tbi. I keep hearing how advancing the timing will make a big difference. I need the know how and what to do. how much advance, do i need to run higher octane, do i need to switch stuff or modify, modify fuel pressure if so how and to what?
  2. moogvo

    moogvo Moderator 1000 Posts 100 Posts

    You have to disconnect the "spout" connector before changing anything. I am not sure where that connector is on that year model. I'm sure someone here knows and can share. Your base timing should be set at 0*, as the computer controls advance. If advancing timing gives and performance benefit, it is only because there is another problem present like a stretched timing chain or worn distributor. If you advance it any more than 5*, you will get spark knock under load. I don't think that there is any gain to timing advance on these engines since the computer controls it anyway.
  3. tbplus10

    tbplus10 Super Moderator Staff Member Platinum Contributor 1000 Posts 100 Posts

    MSD used to sell a replacement electronic ignition module for this model truck that had the ability to advance or retard the timing, I think it only allowed for something like +/- 4deg. It was a popular addition when running water injection systems.
    I gotta agree with Tom, this particular ignition system is pretty accurate, advancing the timing would only be making up for something that may be degrading and should be replaced before it creates major damage internally.
  4. K15 Blazer Guy

    K15 Blazer Guy New Member 100 Posts

    I was talking to someone with this engine in his capreis?... yknow... the chevy police car.
    anyway, he said he tuned up the timing for 91 octane and gained a few MPG.
    but idk if its worth it for just a few mpg.... so im not about to mess with my timing on an engine thats been dependable, and to pay 20cents a gallon more for 91 gas
  5. moogvo

    moogvo Moderator 1000 Posts 100 Posts

    The caprice has the same engine control system as the trucks. Advancing the timing to the point where you have to run higher octane fuel to keep it from spark knocking really isn't going to get you much in the way of returns. You won't see any performance gains and the fuel economy you MIGHT stand to gain are out weighed several times over by the additional cost of the fuel you have to buy to make it run decent, which, at the end of the day sort of cancels out any benefit you could receive.

    To go back to your original statement... Advancing the timing will not benefit you one bit. Those who say different are feeling the placebo effect. To get performance gains, you would have to do a lot more than advance the timing 4* and run high octane fuel. Usually one advances the timing to get the most out of major engine components they have changed, not by itself hoping for the best.

    But hey! Give it a shot! You can always change it back later!
  6. K15 Blazer Guy

    K15 Blazer Guy New Member 100 Posts

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