Iain T Posted January 5 Report Share Posted January 5 Anyone's starter for 10. I have a higher compression ratio of about 10.5:1 therefor the fuel/air mixture is compressed more than in a standard 9:1(?) head. Basic physics tells us when a gas is compressed it generates heat. Given the above posts regarding speed of flame would my head with the aid of compressed molecules and generated heat require less ignition advance than a standard 9:1 head? Iain Link to comment Share on other sites More sharing options...
Pete Lewis Posted January 5 Report Share Posted January 5 in general I reckon the answer is probably Yes more efficiency demands less advance Pete Link to comment Share on other sites More sharing options...
Iain T Posted January 5 Report Share Posted January 5 27 minutes ago, Pete Lewis said: in general I reckon the answer is probably Yes more efficiency demands less advance That's my thinking hence when I previously had my advance at over 20 degrees the engine pinked but nicrguy1966 doesn't. Iain Link to comment Share on other sites More sharing options...
Pete Lewis Posted January 5 Report Share Posted January 5 the best part of getting old is you cant hear the pinking !!! Im an expert aye ..What noise Pete 3 Link to comment Share on other sites More sharing options...
johny Posted January 5 Report Share Posted January 5 3 hours ago, Iain T said: Anyone's starter for 10. I have a higher compression ratio of about 10.5:1 therefor the fuel/air mixture is compressed more than in a standard 9:1(?) head. Basic physics tells us when a gas is compressed it generates heat. Given the above posts regarding speed of flame would my head with the aid of compressed molecules and generated heat require less ignition advance than a standard 9:1 head? Iain A higher octane fuel would help here with pinking so that the mix doesnt ignite prematurely before the flame front reaches it... Link to comment Share on other sites More sharing options...
Iain T Posted January 5 Report Share Posted January 5 2 hours ago, johny said: higher octane fuel would help Tesco Momentum 99 octane for most of my refills. 1 Link to comment Share on other sites More sharing options...
Iain T Posted January 6 Report Share Posted January 6 20 hours ago, Pete Lewis said: the best part of getting old is you cant hear the pinking !!! I call that wife mode. It's that background noise that is sometimes annoying but ignore at your peril! I'm sure my wife can hear me typing this.......... Iain Link to comment Share on other sites More sharing options...
Chris A Posted January 6 Report Share Posted January 6 1 hour ago, Iain T said: I'm sure my wife can hear me typing this.......... Iain She won't need to hear you typing, simply thinking those sort of things is enough 1 Link to comment Share on other sites More sharing options...
Wagger Posted January 6 Report Share Posted January 6 7 hours ago, Chris A said: She won't need to hear you typing, simply thinking those sort of things is enough I hope that you do not have a wireless keyboard?? Link to comment Share on other sites More sharing options...
Iain T Posted January 7 Report Share Posted January 7 19 hours ago, Wagger said: hope that you do not have a wireless keyboard?? I only use my phone for this forum! Link to comment Share on other sites More sharing options...
johny Posted January 7 Report Share Posted January 7 On 06/01/2024 at 12:23, Chris A said: She won't need to hear you typing, simply thinking those sort of things is enough And I thought it was just my other ladies I had to keep secret from the wife! Link to comment Share on other sites More sharing options...
daverclasper Posted January 11 Report Share Posted January 11 Hi. Without re-reading this long post (I've forgotten a lot), I'm a bit confused. From what I recall, it suggests that advancing the timing a fair bit, can help, to counteract the difference with, modern fuels?. I have always understood?, that you generally, had to retard the ignition, to counteract/assist, with the burning of modern fuels?. Thanks, Dave Link to comment Share on other sites More sharing options...
johny Posted January 11 Report Share Posted January 11 Theres two issues here Dave. One, lower octanes than our cars were designed for which as you say can be counteracted by retarding ignition. Then two, the increasing percentage of ethanol being added which is much more of an unknown. For the latter we're postulating that advancing the ignition might produce more efficient combustion because the ethanol burn is slower and so possibly not completing until too late... Link to comment Share on other sites More sharing options...
daverclasper Posted January 11 Report Share Posted January 11 (edited) 24 minutes ago, johny said: Theres two issues here Dave. One, lower octanes than our cars were designed for which as you say can be counteracted by retarding ignition. Then two, the increasing percentage of ethanol being added which is much more of an unknown. For the latter we're postulating that advancing the ignition might produce more efficient combustion because the ethanol burn is slower and so possibly not completing until too late... Thanks for simplifying/summarising the thread Johny. As a layman with a standard car, in general use, I guess, I'll just keep with the "Retard, until it stops pinking" ,technique. Edited January 11 by daverclasper Link to comment Share on other sites More sharing options...
johny Posted January 11 Report Share Posted January 11 Yes no point advancing if youve got pinking. However if not some people are trying more advance than the manual setting... Link to comment Share on other sites More sharing options...
nicrguy1966 Posted January 11 Author Report Share Posted January 11 9 minutes ago, johny said: Yes no point advancing if youve got pinking. However if not some people are trying more advance than the manual setting... I'm advancing the timing and going for a drive to see how it performs in various conditions, from low rev hill starts to acceleration from 50-70 on the motorway. Even after adjusting the cam timing, with the ignition timing set to 'standard' low rev power was very poor. So far, each time I've advanced the ignition, overall performance has improved. Trial and error will continue through the winter months, with maybe another play with the cam timing when the weather warms up. Link to comment Share on other sites More sharing options...
Iain T Posted January 12 Report Share Posted January 12 (edited) 12 hours ago, nicrguy1966 said: I'm advancing the timing and going for a drive to see how it performs in various conditions, from low rev hill starts to acceleration from 50-70 on the motorway. Do you know what your advance is now? Thread drift....everytime I see your profile name I pronounce it knicker guy a play Pink Floyd's Arnold Layne in my head! Yes my wife thinks I'm odd🤪. YouTube the song, a classic! Iain Edited January 12 by Iain T Link to comment Share on other sites More sharing options...
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