using a timing light.

Discussion in 'Engine Topic' started by LayZ, Oct 16, 2016.

  1. LayZ

    LayZ Veteran Member

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    ok give me some basics, I bought a cheapy one from advanced auto the one where you can dial the advance it. I had to replace my fuel bowls and since I was doing that bought new needles and seats. car is backfiring out of the carb bad. So I wanted to check the timing, now should I start on 0 dial it in and then do the advance on the light? Right now the light is saying 60 degrees advance, seems kinda high to me but it is zero'd out on the timing mark.
     
  2. mrdragster1970

    mrdragster1970 Veteran Member Lifetime Gold Member

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    60 is high!!!!

    I do it the same way for decades, check at idle, check at full advance, so you know how much advance is built in.
    If you have a stocker, adjust for full advance.
    If you have an aftermarket, adjust for idle, and tune for the proper ramp, so full advance is correct.

    Do you know or can you look up the specs on your exact combo??

    .
     
  3. mark wagner

    mark wagner Veteran Member

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    what year is the engine? earlier engines timing was set advanced, later were retarded (for emissions), I don't recall ever setting timing to zero
     
  4. fester

    fester Veteran Member

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    Old timer method... no fancy tools, by ear or if you have a tach. use it. Advance the distributor until the engine reaches max idle RPM then starts to drop off, then retard until the max is reached again. then retard it until you lose 50 RPM this will run and start until you can get a proper timing light. Prior to the mid 70's nearly all Small block Chevys were set between 12 and 14 degrees advanced depending on compression ratio and fuel grade you were using. It will run at zero but will be gutless and your exhaust gas temps will be really hot-high.
     
  5. fester

    fester Veteran Member

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    Addendum: The reason the emissions Gurus decided to retard the timing was to raise the exhaust gas temps to make sure to get rid of unburned hydrocarbons, never mind how pooty and inefficient the engines ran..less fuel mileage, more lbs per hour of fuel burned etc.. the new computer controlled cars have taken care of most of those problems, enjoy the new stuff...
     
  6. night rider

    night rider Veteran Member

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    Take the vac line off of the dist. and cap it off. Put timing gun to 0, crank engine. Point gun at damper/tab. Read the number on the tab OR turn knob on gun until hash mark on damper lines up with the 0/TDC mark on tab, now read number on gun's dial. That is your timing at idle.

    Now chart out on paper Idle, 1000 rpm, 1500, 2000, 2500, 3000, 3500, 4000
    And do the above for each of those RPMs and write down results. Hold engine at say 3000 rpm, point gun at damper, turn knob on gun till the mark lines up with the 0 on tab, read number on dial.

    Turn your dist. body to advance/retard timing. Set timing to 14-18* at idle (depending on your combo) and total timing at full advance should be in the 34-38* range
     
  7. LayZ

    LayZ Veteran Member

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    I'm guessing it's the older 454 block gen IV.
    It does have a cam in it so it's not stock. Just seems funny that changing the needles and bowls would screw up the timing. I figure it's running rich that why the back fire out of the carb. Plus I saw some smoke coming out of the breathing tube in the primaries.
     

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