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| Link to advancing the stock timing? | |
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| Tweet Topic Started: Jan 18 2010, 07:34 PM (2,759 Views) | |
| Hollywood | Jan 18 2010, 07:34 PM Post #1 |
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Elite Member
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Is there a tutorial on how to advance timing. I have read it is a good thing to advance the stock timing? I looking forward to getting the 3tech timing setup but until then i'd like to see what how i can best mod the stock. |
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| obaja | Jan 18 2010, 08:13 PM Post #2 |
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Diesel Power
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pretty basic. You need a timing light a tiny wire to jumper diagnostic plug and a torx socket to loosen distributor. Harbor freight is where i got my timing light. It was 15 bucks vs 40 bucks at the auto store. You have all that stuff? |
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| Woodie | Jan 19 2010, 06:27 AM Post #3 |
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Mark where it is now by scribing a line across the housing of the distributor and the cast aluminum piece it bolts to, right next to the adjustment bolt. Turn it toward the firewall (clockwise as you look at it from the driver's side front wheel) about halfway between where it is now and the end of the slot. Drive it for a few days and listen closely for ping, a slight rattling noise that sounds like marbles in the top of the engine, usually appears at two thirds throttle in third or fourth. If you don't hear any ping, move it further, if you do, back it off some. Most G10's will run best around 12 degrees advance, which is very close to the end of the slot. Ping can be damaging to the engine, and varies according to engine condition, weather conditions, gasoline quality, etc. You must continue to listen for ping for the rest of the life of your car, you're exploiting the safety margin the factory put in there to allow for all the above factors combined with drivers who treat a car like a toaster, just use it without regard to any noises it might make or other hints to its condition. A subtle pinging that you hear fleetingly once a day or so is fine, but if it's making noise often, or going on for five seconds, you need to back off on the timing. |
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| Hollywood | Jan 19 2010, 04:28 PM Post #4 |
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Elite Member
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Dont have the timing light but i can pick one up at Harbor freight. Im familiar with the pinging which will usually occur in most cars when under load or going uphill. Thank You guys for the tips. I'll keep you posted when i get to it. |
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| mwebb | Jan 19 2010, 10:58 PM Post #5 |
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FOG
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i do not know what your goal is , what you hope to achieve by advancing your base ignition timing beyond about 8 degrees BTDC but i can tell you if you are seeking to improve your fuel economy ... advancing your base ignition timing beyond about 8 degrees BTDC will not improve your fuel economy in fact ![]() advancing base ignition timing beyond about 8 degrees BTDC DID reduce fuel economy in my car starting from 27 degrees BTDC and dropping 5 degrees per tank of fuel to 8 degrees BTDC ![]() and at the end of my experiment my cat converter was fraked ....21 psi of back pressure at no load WOT snap ![]() right click on image , select view image , click 2x to expand image except by SWAG i can not show that one had any cause and effect on the other but it is a hell of a coincidence Edited by mwebb, Jan 19 2010, 11:05 PM.
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| Woodie | Jan 20 2010, 06:17 AM Post #6 |
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It is a universal truth that gasoline internal combustion engines run best with the maximum amount of timing advance that can be run without ping. That is the entire reason for a knock sensor on newer engines, they don't have to design in the safety margin (and thereby lose power and mileage) the computer keeps advancing until it "hears" ping, exactly as I described above, but in real time. Don't let the fact that mwebb's single car didn't react the way all other cars do scare you off, his is the exception to 100 year old rule. |
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| mwebb | Jan 20 2010, 12:22 PM Post #7 |
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FOG
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my momma always told me i was special .... and now , it seems i have a special car too ? ================================================== it is easy enough to to test your self . record your fuel economy (as you should be doing anyway) make no other changes ; then advance your base ignition timing - see if your fuel economy changes , improves ? gets worse ? stays the same ? post your test results maybe your car is special too |
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| starscream5000 | Jan 20 2010, 12:44 PM Post #8 |
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Got 70 MPG?
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I did not notice a gain in FE after 10 BTDC on mine. In my worn out motor I had to use premium to keep it from knocking, which fiscally, did not make enough sense for me to continue on. I now have it backed down 8 BTDC with 89 octane as a little "overhead" in case it were to ping on 87, which I have detected before under load at this setting. |
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| Bad Bent | Jan 20 2010, 02:43 PM Post #9 |
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Facetious Educated Donkey
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Hollywood... Here is a link for setting the timing with a timing light on a vacuum advance engine, namely my '91 and it shows how to set up the timing light.http://geometroforum.com/topic/Timing If you'd like I can do a short video.... |
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| Dallas | Jan 20 2010, 03:41 PM Post #10 |
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you gain economy by advancing timing because it increases the peak cylinder pressure at the top of the compression stroke, thereby being forced downward with increased velocity. this is why you make more power also. there is a fine line as to how much peak pressure can be achieved before it slows the piston down too much vs the increased downward speed- this happens BEFORE you hear any audible knocking, and would be considered your max point. actual pinging/knocking is passed that threshold too far that you are physically damaging your engine* you need to time it perfectly as to not waste the energy coming up compression a volume that is already exploding/expanding before sending all that energy back down. too much cylinder pressure and you blow headgaskets or pistons (too much shock), every degree added will increase efficiency up to a certain point. higher octane fuel burns slower, therefore allows a few degree of crankshaft rotation before it explodes completely. Im a believer in maximizing ignition timing, but the stock system gives you virtually no control. maximizing timing at cruise/static rpms is very beneficial * - depends on the motor, some engines can withstand all sorts of knocking and not be hurt, but when you get into hot weather, or forced induction, your threshold of how much knocking it can take is drastically reduced. especially in higher rpms, a 3cyl spinning 100rps (6000rpm) is going to have FIFTY knocks per second. the audible noise you hear on the outside is the engine basically vibrating from shock. if its like a ting---ting---ting---ting its safe to say you arent causing nearly as much damage as a click-click-click-click, but ANY audible knock is no good for a motor. it will only take it for so long |
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| mwebb | Jan 20 2010, 06:09 PM Post #11 |
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FOG
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http://farm4.static.flickr.com/3432/3869589018_ec05ef56c1_b.jpg![]() right click on image , select view image , click 2x to expand image these test results would appear to show slight increase in torque and horsepower as a result of advancing base timing from 6 to 10 degrees except , the people running the test were setting the mixture s to run leaner than stoich this PDF of theses test results is available on the net for those who have a mind to view it i can not find any other test results as comprehensive as these . these test results may or may not be valid outside of the lab they were run in . this 10g engine was not mounted in a car during the test . ======================================= for those posters who claim advancing base ignition timing absolutely will improve something show me the test results show me what you did and the improvement that you measured you will find that theory very often conflicts with what happens in the real world it should be noted that in these test results are graphs showing peak pressure and when in degrees of engine rotation it occurs it is always considerably after TDC and varies considerably as well based on many variables Edited by mwebb, Jan 20 2010, 06:16 PM.
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| Dallas | Jan 20 2010, 09:18 PM Post #12 |
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I cant quote any statistics, but from real world experience driving my car 700+km a week, the more advance I was able to get in it, the more economy I got, and definitely noticed a power improvement for every 1 degree I was able to add to the map at 20psi. I was able to add three more degrees and it was a day/night feeling, perhaps I wasnt close enough to the edge before, but the mechanics are all the same, advance to the point of highest safe combustion chamber pressure and not exceed. its as simple as that. just theory here, but lets say you have 150psi compression in each cylinder. that is without the fuel combusting before it hits the top of the stroke (you wouldnt be able to do a peak pressure test without expensive equipment). iirc, cylinder pressures are about 10x that in a running environment at full throttle (and for the sake of the argument, we will assume that 1500psi is the max safe psi). now for the same (opposite) reason you retard timing when you force more air in (be it the throttle plate opening more on an NA car, or more boost on a turbo car) you need to advance the timing at lower loads. when you are cruising along in the city at part throttle, you dont have enough air/fuel to hit the highest pressure, so you compensate by advancing the timing, so by the time your little amount of air/fuel ignites, the piston is still completing its compression stroke, so its expanding before it hits the top, therefore increasing peak pressure by firing the spark earlier. THIS is where I believe the timing change makes the most effect. at cruise, and may cause it to knock at higher throttle positions. you should notice improved torque off idle and a higher vacuum reading up to the point of diminishing returns (pre-knock), but at cruise, the higher the timing the better. its almost impossible to make it knock at 10% throttle at 2000rpm putzing along, and you can advance a crapload of timing there usually. for reference, here is a timing map for my 3cyl (note that I found the timing to be too far advanced below 2500rpm in this particular map and dropped about 5-7 degrees out of it) ![]() on the left, 40kpa is around idle/cruise vacuum, 80-100 is normal accel (100 is also WOT for a non turbo) 200 is 14.7psi and 255 is somewhere around 23 see how the timing changes based on load and rpm? (I just posted all of this in general, adding to the topic not so much arguing, because I am on a different ecu than you guys, and I know for a fact more advance = more economy.... for all I know the stock ecu is already very aggressive with its timing and THAT is why you dont gain anything in stock form) sorry if this was too all-over-the-place, im soooo tired |
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| mwebb | Jan 20 2010, 10:38 PM Post #13 |
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FOG
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http://somender-singh.com/uploadfiles/Herning_Tests_Analysis.pdf i think you would find this to be interesting 67 pages you can print it and read it when you get a minute or two i have captures made with engines with two spark plugs in the cylinder head , like a ford ranger for instance and mercedes e320 pressure transducer in one of the spark plug threads with the engine running even at WOT combustion pressure will almost never approach 500 psi let alone 1500 psi these engine are not boosted , no turbo . i have an engineering PDF that discusses this and in that paper max combustion pressure they obtained was 248 psi or 1710 kpa at at the spark 2k rpm at WOT . under "full" load , peak combustion pressure occurred at 22 degrees ATDC was 548 psi or 3780 kpa which was the highest pressure at any rpm or load in there test i can email it if anyone wants it . i have the pressure transducers , they are not so expensive , there is however a wee bit of a learning curve to get fluent in using them. for this type of work , the fluke pv 350 is the way to go ,it is the only one i have used that will hold zero after zero has been set to local ambient baro pressure you seem to be able to record mileage and how much fuel you are using ... do the math if there is an improvement in your car you should be able to document it ? so ? with base timing advanced in 5 degree increments up to a max of 27 degrees btdc measured which on my car is the distributor against the stop . i did the math . in my "special" car there is NO improvement in fuel economy - unless you put a negative sign in front of the "improvement" let us also remember at the end of my experiment - my cat converter had 21 psi of back pressure at WOT with no load something it did not have prior to my experiment . a "good" or "normal value would be about 2 psi so although that is not conclusive proof it would seem that combustion efficiency was reduced so much by the "experiment" that my cat converter was destroyed Edited by mwebb, Jan 20 2010, 11:04 PM.
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| Johnny Mullet | Jan 20 2010, 10:59 PM Post #14 |
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Fear the Mullet
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Advancing the timing on a Suzuki G10 or G13 from the stock setting to 8-10 degrees advanced does one thing............... Prevents burnt valves. |
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| mwebb | Jan 20 2010, 11:08 PM Post #15 |
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FOG
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while i agree, anecdotal evidence and my own experience in my g10 shows optimum base ignition timing to be 8 to 10 degrees BTDC ================================ how does it prevent a burnt valve ? |
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