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If you seem to have more power you might get better fuel milage. The problem is you do not want the engine getting it's fuel so early it is trying to reverse the direction of piston travel. Still wastes fuel even if no audible Pre detonation. Watch your temperature gauge is it the same or less in general? You should sense a better drivability as well if all is well. Listen to your engine carefully. Do you hear a larger background knocking then you did before? If not all should be well. Also suprisingly although against common sense the idle is smoother when the car is ahead of the factory settings as long as not too far. Because of many factors it would not suprise me that 8 degrees advance over factory designated setting works well for your engine only. You could verify by the milli volt method. I do not think it is detrimental to tune to the highest voltage reading. The rotating inertia present means you are really not advancing too far with that method I suspect. Just to the point of maximum efficiecy for your engine. Plus it may be the best indicator of efficient fuel usage. Just drive it for ten minutes and post if there is more noticable power and it is pulling properly. Without your initial test getting messed up you would be still at the factory recomended point and that would have been a shame if my thinking is correct. Each engine is going to respond a little different as things like injector pop,compression, actual valve timing, fuel used, plus many more variables are always a little different by and large with each older engine plus we have not even got into injector pump aging to any extent yet. What is causing me to think and activate my old rusty brain is how the factor of available compression with used engines is playing in to all of this. If your compression is say down 10 percent from new on average for a random number is it not obvious the ignition point of the fuel is going to be later in reality as the ignition temperature remains the same but that point is not reached until the piston has moved a small amount higher in the cylinder? Meaning the factory marks are no longer exactly valid. I now suspect it to be a large component. Please post your observations. The present car I am driving although volkswagen is producing above average fuel milage plus great power with a quieter idle than it ever did. If it had been set by ear I think I would have advanced the pump until I heard the excess rattle and backed off a little. Results would have been no better than the factory setting for milage perhaps. Other than indicated power is greater. Because it may be in reality be over advanced. Not to the extent of damaging the engine but not at the most efficient setting. That would not have been good but maybe because of all the indirect aging things that are present in an old engine the milli volt method does it all for you. We will see. You are at the trial and error stage in my opinion the way you have done yours. Hope this milli volt thing works out. Also hope by accident you have hit the sweet spot of both highest possible fuel efficiency combined with best power consistant with it as well. That way you are not and cannot be too far advanced. As soon as you are even the slightest amount too far advanced the fuel utilization is reduced and combustion temperature starts to fall. That is under test conditions by miilivot method. In reality under driving or load it might get hotter as it is less efffecient and you are burning more fuel creating heat. Remember there are less btus in less fuel. Or more fuel equals higher temperatures. I will have to think about this for awhile. The power gain is then somewhat illusionary as you only get it an acceleration it seems rather than across the board. Although you will have some obvious gain. The position we really seek is incrementally very, very small on the movement of the pump near the final resting place obtained by just the slightest of taps that produced no visible movement on the vw pump. I am going to make sure to do two more over the weekend as I feel in is now important to pay attention to details. Plus it is required that the present results prove to be repeatable. Also it is getting to the point I have to know if some of my seemingly abstract thinking is accurate. Your eight degrees is a lot of advance from the factory recomendation. That remark I have to concur with. If proven viable it should upset present applecarts of thought. By my reasoning and your description it may be too far but only time observation and usage will indicate but would hate to see pre ignition at high revs because of the designed advance curve in the pump. Keep an eye and ear on things. Main thing is let us know how it plays out. I for one will be watching.
Last edited by barry123400; 05-12-2006 at 12:45 PM.
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05-11-2006, 08:47 PM
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