C
C3RVETTE
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How to Set Ignition Timing -- 1 of 1
Here’s a step-by-step on how I set the initial ignition timing. I start the engine and let it run until it's warmed up. I then shut it down, and disconnect the EST wire, (it's a SINGLE wire that is tan in color with a black stripe and is located just under the power brake booster/windshield wiper motor area). I get out my 3/8" ratchet and distributor wrench, adjust the ratchet to the loosening position, and place it on the passenger side tire. The distributor wrench is shaped like an "L" and makes getting to the distributor bolt much easier than using a straight 9/16" open end/box end wrench. I then connect my timing light to the #1 spark plug wire and the other two clips to the battery; red to positive and black to negative. I don't have a self-powered timing light; mine uses battery voltage. I then start the engine. It may be a little difficult to keep running at first with the EST wire disconnected. That's the reason I let the engine warm up first; makes it a little easier to get it to idle by itself. Once the engine settles down and idles by itself, I point the timing light at the harmonic damper and see where the groove in the harmonic damper aligns with the timing tab on the timing chain cover. The stock setting is 6 degrees Before Top Dead Center (BTDC). Each little line on the timing tab should equate to 2 degrees. If the timing needs adjustment, I walk to the passenger side of the engine and loosen the bolt that secures the distributor to the intake manifold (you have to access it from the passenger side). I loosen the bolt just enough to allow me turn the distributor with my hand. I adjust the ratchet to the 'tighten' position and leave the ratchet and distributor wrench in place, kind of standing up but still on the head of the bolt. I then return to the driver's side of the engine, point the timing light at the damper again, pull the trigger and turn the distributor with my hand while watching the groove on the harmonic damper move. Once the mark on the damper aligns where I want it, I reach over and give the ratchet a turn to tighten the distributor hold down bolt. I then check to see that the timing I'd selected hasn't moved. It will sometimes as you tighten the hold down bolt. If it has moved, I loosen the bolt, make the necessary adjustment by turning the distributor (again) in the require direction. Then I tighten again. Once I have the timing set to where I want it. I walk over to the passenger side of the engine again and tighten the bolt completely. I then go back to the driver's side and verify that the timing hasn't moved. Then, I shut down the engine, re-connect the EST wire, remove the timing light connections and disconnect the battery (just one cable) for about 30 seconds. This clears the code that gets automatically set when the computer detects the engine running with the EST disconnected. I try to work as fast as I can because with the engine idling with only 6 degrees of timing advance, the headers/exhaust will begin to glow red due to the engine not having enough timing advance. Once the engine is re-fired with the EST re-connected and code cleared, the timing mark should be just off the scale of the timing chain cover tab. up near the 12 o'clock position. You can re-connect the timing light if you want to check it. That's it. Figuring out the timing marks has tripped up a lot of guys, so don't fret. Most timing tabs are marked in two-degree increments. Each little hash line on the timing tab indicates two degrees difference from the hash line nearest it. You mau not see actual numbers, like 2, 4, 6, etc., all you may see are just little lines cut in the timing tab. Tabs differ, but there is usually ONE spot on the tab that is marked ZERO, has the letter "0", has a deeper notch or longer hash line than the others. Something that makes it different from all the other marks on the timing tab. That's the sucka you have to identify first; all changes are made in direct reference to it. The damper has a groove cut in it which is 'supposed' to coincide with the #1 piston being at TDC (Top Dead Center). This isn't always accurate, but unless you want to go to all the trouble of verifying it, just accept it as being cut in the correct place. Most guys mark those spots (ZERO on the tab and TDC on the damper) with something that will make them stand out when the timing light is flashed at it. I use red fingernail polish, others use whiteout, etc. The ignition advance is determined by where the groove in the damper aligns with the little hash mark on the timing tab. If you are standing on the driver's side of the engine, those marks on the timing tab that move away from you, which also causes it to move away from the ZERO mark (in a counter clock-wise direction) are advance marks. Those that move toward you (in a clock-wise direction from the ZERO mark) are the retard direction. So, for each little hash mark on the timing tab that you move the damper groove you've changed the timing two degrees. If you move the damper groove counter-clock-wise (away from you) you're advancing the timing and if you move it clock-wise (toward you) you're retarding it. With the EST disconnect, the engine will idle noticeably better as you advance the timing and noticeably worse as you retard it. Do be fooled; sticks to the stock setting of 6 degrees, or at best 8 degrees. Modified engines may call for more initial advance that 8 degrees, but for a basically stock setup, stick with a max of 8. Remember, the directional references I listed are with you standing on the driver's side of the engine. If you can picture yourself standing directly in front of the engine, facing it (which won't do a lot of good since you wouldn't be able to see any of the timing marks from THAT position), clock-wise and counter clock-wise applies.
Here’s a step-by-step on how I set the initial ignition timing. I start the engine and let it run until it's warmed up. I then shut it down, and disconnect the EST wire, (it's a SINGLE wire that is tan in color with a black stripe and is located just under the power brake booster/windshield wiper motor area). I get out my 3/8" ratchet and distributor wrench, adjust the ratchet to the loosening position, and place it on the passenger side tire. The distributor wrench is shaped like an "L" and makes getting to the distributor bolt much easier than using a straight 9/16" open end/box end wrench. I then connect my timing light to the #1 spark plug wire and the other two clips to the battery; red to positive and black to negative. I don't have a self-powered timing light; mine uses battery voltage. I then start the engine. It may be a little difficult to keep running at first with the EST wire disconnected. That's the reason I let the engine warm up first; makes it a little easier to get it to idle by itself. Once the engine settles down and idles by itself, I point the timing light at the harmonic damper and see where the groove in the harmonic damper aligns with the timing tab on the timing chain cover. The stock setting is 6 degrees Before Top Dead Center (BTDC). Each little line on the timing tab should equate to 2 degrees. If the timing needs adjustment, I walk to the passenger side of the engine and loosen the bolt that secures the distributor to the intake manifold (you have to access it from the passenger side). I loosen the bolt just enough to allow me turn the distributor with my hand. I adjust the ratchet to the 'tighten' position and leave the ratchet and distributor wrench in place, kind of standing up but still on the head of the bolt. I then return to the driver's side of the engine, point the timing light at the damper again, pull the trigger and turn the distributor with my hand while watching the groove on the harmonic damper move. Once the mark on the damper aligns where I want it, I reach over and give the ratchet a turn to tighten the distributor hold down bolt. I then check to see that the timing I'd selected hasn't moved. It will sometimes as you tighten the hold down bolt. If it has moved, I loosen the bolt, make the necessary adjustment by turning the distributor (again) in the require direction. Then I tighten again. Once I have the timing set to where I want it. I walk over to the passenger side of the engine again and tighten the bolt completely. I then go back to the driver's side and verify that the timing hasn't moved. Then, I shut down the engine, re-connect the EST wire, remove the timing light connections and disconnect the battery (just one cable) for about 30 seconds. This clears the code that gets automatically set when the computer detects the engine running with the EST disconnected. I try to work as fast as I can because with the engine idling with only 6 degrees of timing advance, the headers/exhaust will begin to glow red due to the engine not having enough timing advance. Once the engine is re-fired with the EST re-connected and code cleared, the timing mark should be just off the scale of the timing chain cover tab. up near the 12 o'clock position. You can re-connect the timing light if you want to check it. That's it. Figuring out the timing marks has tripped up a lot of guys, so don't fret. Most timing tabs are marked in two-degree increments. Each little hash line on the timing tab indicates two degrees difference from the hash line nearest it. You mau not see actual numbers, like 2, 4, 6, etc., all you may see are just little lines cut in the timing tab. Tabs differ, but there is usually ONE spot on the tab that is marked ZERO, has the letter "0", has a deeper notch or longer hash line than the others. Something that makes it different from all the other marks on the timing tab. That's the sucka you have to identify first; all changes are made in direct reference to it. The damper has a groove cut in it which is 'supposed' to coincide with the #1 piston being at TDC (Top Dead Center). This isn't always accurate, but unless you want to go to all the trouble of verifying it, just accept it as being cut in the correct place. Most guys mark those spots (ZERO on the tab and TDC on the damper) with something that will make them stand out when the timing light is flashed at it. I use red fingernail polish, others use whiteout, etc. The ignition advance is determined by where the groove in the damper aligns with the little hash mark on the timing tab. If you are standing on the driver's side of the engine, those marks on the timing tab that move away from you, which also causes it to move away from the ZERO mark (in a counter clock-wise direction) are advance marks. Those that move toward you (in a clock-wise direction from the ZERO mark) are the retard direction. So, for each little hash mark on the timing tab that you move the damper groove you've changed the timing two degrees. If you move the damper groove counter-clock-wise (away from you) you're advancing the timing and if you move it clock-wise (toward you) you're retarding it. With the EST disconnect, the engine will idle noticeably better as you advance the timing and noticeably worse as you retard it. Do be fooled; sticks to the stock setting of 6 degrees, or at best 8 degrees. Modified engines may call for more initial advance that 8 degrees, but for a basically stock setup, stick with a max of 8. Remember, the directional references I listed are with you standing on the driver's side of the engine. If you can picture yourself standing directly in front of the engine, facing it (which won't do a lot of good since you wouldn't be able to see any of the timing marks from THAT position), clock-wise and counter clock-wise applies.
