zzzzed Posted February 6, 2016 Share Posted February 6, 2016 (edited) I have recently swapped my standard points distributor for a Mallory electronic distributor First issue was I had to reduce the timing from 10 degree down to 5 degree to stop detonation Second issue is that I am now getting preignition after longer drives. Could the stronger spark be making the fuel mixture lean? I am running British Su carbs from an Austin Healy on a standard l28. Edited February 6, 2016 by zzzzed Quote Link to comment Share on other sites More sharing options...
Jason89 Posted February 7, 2016 Share Posted February 7, 2016 Try colder plugs. You may have more heat in the combustion chamber due to a better burn. Quote Link to comment Share on other sites More sharing options...
RLY240 Posted February 7, 2016 Share Posted February 7, 2016 Sounds like the new dizzy has a greater mechanical advance, do you know what the total advance is? The Nissan ones are stamped on the weights, ie 7 on each weight totals 14 deg advance. Roger Quote Link to comment Share on other sites More sharing options...
zzzzed Posted February 8, 2016 Author Share Posted February 8, 2016 Sounds like the new dizzy has a greater mechanical advance, do you know what the total advance is? The Nissan ones are stamped on the weights, ie 7 on each weight totals 14 deg advance. Roger That wouldn't make it preignite though would it. I thought it might be a carbon build up and now it is burning hotter the carbon is making it preignite Quote Link to comment Share on other sites More sharing options...
zzzzed Posted February 8, 2016 Author Share Posted February 8, 2016 Hmm I think the total advance of the dizzy is around 22 degree Quote Link to comment Share on other sites More sharing options...
peter mc Posted February 16, 2016 Share Posted February 16, 2016 First. Spark dose not cause a car to run on .as soon as you turn the ignition off theres no spark ...can i ask did you turn the idle screw up after you had to retard the timing. .? Also combustion chamber may have hot spots in it from running retarded timing Quote Link to comment Share on other sites More sharing options...
zzzzed Posted February 28, 2016 Author Share Posted February 28, 2016 I havnt touched the idle speed. I might up the timing a couple of degree and see if I can add a bit of fuel to the mix to try stop the pinging Quote Link to comment Share on other sites More sharing options...
oldmates260z Posted February 28, 2016 Share Posted February 28, 2016 I have had similar issues with my L28 with flat tops....found my dizzy was only going to 20-25 DBTC You should check Ignition timing- should be around 34-36 degrees at 4000 rpm Quote Link to comment Share on other sites More sharing options...
zzzzed Posted February 28, 2016 Author Share Posted February 28, 2016 Ahh ok. I think I need to get it on th dyno and let some one who knows what they are doing have a go. Quote Link to comment Share on other sites More sharing options...
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