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Advancing pump timing on stock 6.2 - negative effects?

Discussion in '1982-Present GM Diesel' started by rich, May 24, 2005.

  1. rich

    rich 1/2 ton status

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    Will there be any negative effects to the stock 6.2 in my 1990 1/2-ton Burb if I advance the pump timing a little?

    The engine has 105k on it and is in good shape. I would like more power, especially when towing my car trailer.

    Everything I have read says to advance the timing 1/8-1/4 inch using the reference marks, and no one has said anything bad about it. Do I have to worry about EGTs or anything - need to wait until I get a pyrometer?

    I am getting a significant amount of black smoke under load, and I have a new air filter.

    Thanks!
    Richard
     
  2. 6.2 man

    6.2 man 1/2 ton status Premium Member

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    I would only advance the timing to just past the line I think an 1/8 or a 1/4 is oo much . As far as the smoke replace your intake with one from a J series engine and your smoke will disappear !!! Also more power and you won't need to monitor EGT's
     
  3. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    I'd agree. 1/32" is a lot when you're talking about pump timing...

    The more you advance the timing the clackier and louder it gets. There is certainly a point where it's way too much and it doesn't take much adjustmant to get there. My 6.2 has 230,000 on it and still has the original timing chain (AFAIK) and my pump is maybe 1/32" past the line.

    A 'J' code intake will allow the motor to breath easier and likely smoke less (as will a high flow exhaust system). The only time i ever see any smoke from mine is when I'm really heavy on the throttle and lugging it (not often...) I port matched my 'J' code intake and bowl blended the area under the air filter housing. Pretty easy job and the "right foot dyno" noticed a difference.

    Rene
     
  4. rich

    rich 1/2 ton status

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    Thanks for the info! I won't mess with my pump timing then.

    I have a J-code intake at home, so I'll bump that up in the list of project priorities. :)
     

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