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  1. #1
    Sr. Mechanic Ethan's Avatar
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    Sep 2009
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    Cedar Park, TX
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    150

    Default Timing issue on a 1994 350 TBI

    I recently did a intake manifold gasket on my truck, and have been trying to get the timing right, but a few things are striking me as odd. First off, I have access to a GM Tech 2 with an OBD 1 connector, so I can see what the computer is trying to do to my timing as I drive. Secondly, the timing tab above my harmonic balancer is all scratched up, so I can't tell where 0 degrees is, so I'm guessing at this point. Originally I put it where it's below the 3 smaller bumps, but inbetween the large last bump. When it was set there, at idle my timing was advanced by 20 degrees constantly, and even if I accelerated, it would stay 20 degrees advanced. So I retarded the timing by 5 degrees, or 1 notch on the timing tab. Now its still idling at 20 degrees advanced, but when I accelerate it retards to 2 degrees advanced.

    I do disconnect the brown with black strip wire under the dash when I time the engine, just in case ya'll wondering. I'm very confused since I know most vehicles will idle at 10 degrees advanced and under acceleration advance to 20 degrees. Since it's staying at 20 degrees advanced, a explanation would be nice, or a way to solve this problem, if it's a problem.
    1994 Chevy Silverado 1500 Ext Cab 350 cuin TBI in dark Chevy blue
    160,000+ miles
    Original paint
    Original interior
    Original engine and tranny
    wrecked twice stolen once
    Diamond Plate bed rails
    Power windows
    Original Alloy wheels
    Original fancy smancy cup holder
    Tow package
    Original plastic bed liner
    K&N Cone Air Intake
    Dual MagnaFlow exhaust(not true dual) with chrome tips
    MSD Street Fire Performance Ignition coil

  2. #2

    Default

    have you watched what it does with the wire connected vs disconnected? have you verified with a light that it's advancing, not just relying on the information from the computer?

    I believe base timing should be like 4-6 degrees advance. don't remember off the top of my head. Your best bet is to get an adjustable timing light so you can just work off of your 0 mark.
    1986 Chevy G20 Tow Rig - 5.7 TBI conversion
    1978 Mustang II King Cobra Road Racer - Holley 650, MSD 6AL, 5 speed, 10 point Roll Cage, 9" posi, fuel cell, custom interior.

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