Dismiss Notice

Welcome To CK5!

Registering is free and easy! Hope to see you on the forums soon.

Score a FREE t-shirt and membership sticker when you sign up for a Premium Membership and choose the recurring plan.

explain something for me

Discussion in 'The Garage' started by tecton, May 5, 2003.

  1. tecton

    tecton 1/2 ton status

    Joined:
    Dec 1, 2002
    Posts:
    1,553
    Likes Received:
    0
    Location:
    WV
    Timing
    what is it
    what does it do
    what does it do if its off
    what does it affect
    mmmm yeah

    (dont get mad, im just trying to learn)
     
  2. chevyfumes

    chevyfumes Court jester

    Joined:
    Feb 24, 2000
    Posts:
    38,584
    Likes Received:
    266
    Location:
    Watch for the muzzleflash!
    makes the electrical spark to the correct chamber at the right time... /forums/images/graemlins/thumb.gif
     
  3. Silver84k5

    Silver84k5 1/2 ton status

    Joined:
    Feb 7, 2002
    Posts:
    3,769
    Likes Received:
    0
    Location:
    Hillsboro Oregon
    if its off, your motor can "ping" it can back fire through the carb, it can "Diesel" when you shut it off, dieseling = when you turn the car off it still wants to run....

    im pretty sure if your engine "pings" for awhile that it can actually blow a hole in the piston,
     
  4. K5MONSTERCHEV

    K5MONSTERCHEV 1/2 ton status

    Joined:
    Jan 27, 2003
    Posts:
    3,254
    Likes Received:
    0
    Location:
    Castro Valley, CA
    It also gives you better fuel economy and power, when it advances, via, the vaccuum advance.
     
  5. Can Can

    Can Can Pusher Man Staff Member Super Moderator

    Joined:
    Feb 17, 2000
    Posts:
    15,552
    Likes Received:
    136
    Location:
    Cochrane, Alberta, Canada
    What is it? - It's the way the distributor is set to send the electrical charge through the spark plug wires to the spark plugs.

    WHat does it do? - See above. When correctly set the spark plug ignites the gas in the cylinder while the piston is at the top of the cylinder.

    What does it do if it's off?- If it's not set right, there's a lot of different ways the motor will react. They include pinging, run-on(dieseling), hard starts, lack of power, and more.

    What does it affect?- Basically, if your timing is off your engine will not work like it should. There are four stages of combustion:

    Suck- The intake valve opens. The gas is pulled into the motor as the piston drops into the cylinder.

    Squeeze- The intake valve closes. The gas/air mixture is compressed as the piston travels upwards in the cylinder.

    Bang- The now-compressed gas/air mixture is ignited by the spark plug, forcing the piston downwards.

    Blow- The burnt gas/air mixture is pushed out of the cylinder as the piston goes up again and the exhaust valve opens to allow it out of the cylinder.

    If your engine isn't banging when it's supposed to, it screws things up!!!!

    Hope this helps, brother.
     
  6. fortcollinsram

    fortcollinsram 1/2 ton status

    Joined:
    Nov 8, 2001
    Posts:
    2,261
    Likes Received:
    0
    Location:
    Fort Collins, CO
    Well there are two kinds of timing...valvetrain timing (when the valves open in relation to crank rotation) and spark timing(when a spark ignites the air/fuel mixture in a given cylinder, also measured in degrees of crank rotation)

    Most of the time, when people talk about timing, they are talking about spark timing...Valvetrain timing is usually within 4-degrees of TDC (Top Dead center)of the number one cylinder.

    Spark timing is an interesting beast. Thespark must ignite the air/fuel mixture at the right moment..too early, and you have pre-ignition (also called detonation) when the air/fuel mixture is ignited when the piston is still on its upward compression stroke..this tries to push the piston down even though it want to continue traveling up.

    If the spark ignites too late, you lose valuable compression of the air/fuel mixture and loose potential power...

    Ideally, at idle, the plug will spark just before or AS the piston reached the top of its compression stroke (the top of the compression stroke is also called TDC)
    You set your timing by rotating your distributor. A timing light is used identify where the spark occurs in terms of crankshaft rotation. On my TBI 350, at idle, I have 0-degrees of advance. This means that when the number one cylinder is at the EXACT top of its compresion stroke, the spark occurs

    As with many things there is a catch...as the engine speeds up, the spark must occur sooner and sooner. This is because the spark takes a split second to ignite the air/fuel mixtue. As engine speeds increase, the plug must spark sooner and sooner so the actual combustion takes place when intended (just as the piston reaches TDC)...Therefore, the engine must have a way of Advancing the timing...newer, fuel injected engines use computer comtrolled distributors to advance the timing..Older engines use either vacuum advance or mechanical advance to advance the timing curve.

    Chris /forums/images/graemlins/thumb.gif
     
  7. chevyfumes

    chevyfumes Court jester

    Joined:
    Feb 24, 2000
    Posts:
    38,584
    Likes Received:
    266
    Location:
    Watch for the muzzleflash!
    [ QUOTE ]
    suck
    squeeze
    bang
    blow

    [/ QUOTE ] Hehehehehehe
     
  8. Can Can

    Can Can Pusher Man Staff Member Super Moderator

    Joined:
    Feb 17, 2000
    Posts:
    15,552
    Likes Received:
    136
    Location:
    Cochrane, Alberta, Canada
    I learned that in high school auto class. For some reason I've never forgotten it........ /forums/images/graemlins/wink.gif
     
  9. chevyfumes

    chevyfumes Court jester

    Joined:
    Feb 24, 2000
    Posts:
    38,584
    Likes Received:
    266
    Location:
    Watch for the muzzleflash!
    Your teacher made you do bad things and that is wrong, you may have a lawsuit..... /forums/images/graemlins/rotfl.gif /forums/images/graemlins/rotfl.gif /forums/images/graemlins/rotfl.gif /forums/images/graemlins/rotfl.gif /forums/images/graemlins/rotfl.gif /forums/images/graemlins/rotfl.gif /forums/images/graemlins/rotfl.gif /forums/images/graemlins/thumb.gif
     
  10. Can Can

    Can Can Pusher Man Staff Member Super Moderator

    Joined:
    Feb 17, 2000
    Posts:
    15,552
    Likes Received:
    136
    Location:
    Cochrane, Alberta, Canada
    But she had such a sweet ass- how could that be wrong??? /forums/images/graemlins/confused.gif

    /forums/images/graemlins/rotfl.gif /forums/images/graemlins/rotfl.gif /forums/images/graemlins/rotfl.gif /forums/images/graemlins/rotfl.gif /forums/images/graemlins/rotfl.gif
     
  11. chevyfumes

    chevyfumes Court jester

    Joined:
    Feb 24, 2000
    Posts:
    38,584
    Likes Received:
    266
    Location:
    Watch for the muzzleflash!
    /forums/images/graemlins/rotfl.gif /forums/images/graemlins/rotfl.gif /forums/images/graemlins/rotfl.gif /forums/images/graemlins/rotfl.gif /forums/images/graemlins/rotfl.gif /forums/images/graemlins/rotfl.gif /forums/images/graemlins/thumb.gif
     
  12. tecton

    tecton 1/2 ton status

    Joined:
    Dec 1, 2002
    Posts:
    1,553
    Likes Received:
    0
    Location:
    WV
    helps alot, thank you

    someone said my truck was "spark knocking"
     
  13. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

    Joined:
    Feb 17, 2000
    Posts:
    7,385
    Likes Received:
    0
    Location:
    Atlanta
    [ QUOTE ]
    helps alot, thank you

    someone said my truck was "spark knocking"

    [/ QUOTE ]
    Several things can cause spark knock. Timing being to far advanced is the big one.. Carboned up valves and combustion chambers, cloged air filters causing the fuel mixture to be lean. Fuel delivery problems cause lean fuel mix, stale fuel, Fuel of to low of octan for the compression ratio.

    You truck if stock should do ok on regular but you might want to run some mid grade through it and see if the problem get's better.

    Now I recomend you do get a shop manual. your truck should have a ESC distributor with a knock sensor. If I'm correct then the Distributor ECU located behind the glove box should be backing off the timing to prevent "Spark knock". For what ever reason it's not doing it. Could be a bad knock sensor or it could be a electronic problem with the Distributor or distributor ECU. It is something you really need to repair because you can cause damage to the engine if it does this often.
     
  14. tecton

    tecton 1/2 ton status

    Joined:
    Dec 1, 2002
    Posts:
    1,553
    Likes Received:
    0
    Location:
    WV
    the guy i bought the truck off of built it up
    my dad said if its cammed that i need to run 92-93 octane....it does idle better with higher octane

    but it will do it when i start it up after its been there a while...it will do it, ill hear like...almost like someone shotting an air gun...then itll run fine til i let it set again
     

Share This Page