720inOlyWa Posted July 22, 2014 Report Share Posted July 22, 2014 When I put my engine back together, I set the timing at 5 degrees- maybe a pudgy five- and it ran fine. I set it there because that’s where it was in the photo in the Haynes guide. I have a thousand miles on it now and I have been trying to smooth it out in transition from idle, so playing around with the timing seemed appropriate. This time, I consulted the back cover of my official Nissan shop manual and it said between 3 and 2 degrees BTDC. So I set it there. It runs great- and maybe picks up from idle a bit better, I’m not sure. But the pinging under load is now evident. The manual says retard it a degree or two if this happens, so I will. That will put me right back to about 5 degrees again. I am sure that five degrees is fine. I am not worried about it. I was just curious about the discrepancy. Is timing an approximate thing when it comes to production cars like my little 720 King Cab? Quote Link to comment
MikeRL411 Posted July 22, 2014 Report Share Posted July 22, 2014 Most likely the pinging is due to the lower actual Octane ratings of gasoline as compared to 30 years ago. Seasonal dilution with Ethanol also contributes to differing ignition. Quote Link to comment
720inOlyWa Posted July 22, 2014 Author Report Share Posted July 22, 2014 You may be right. However, when I squinted my tired old eyes ad read the fine print again, it said: “3 degrees, plus or minus 2 degrees”, which can easily put me back at five degrees, right? Ooops. sorry. I don’t have a problem after all! Quote Link to comment
datzenmike Posted July 22, 2014 Report Share Posted July 22, 2014 If you are at 3 degrees retarding it 2 degrees goes down to one. Advance means more or + timing. Retard means backward or - less timing. The NAPS are very tolerant of too much advance, they don't ping much but they don't give the best power either. The correct timing is 3 degrees + or - 2 degrees (that's +5 down to +1 degrees BTDC) to allow for different grades of gas, temperature, humidity, altitude and temperatures. All of which affects the timing. 1 Quote Link to comment
NissanEgg Posted July 25, 2014 Report Share Posted July 25, 2014 Well, what would you recommend on a Z20S with Z24 dizzy, a Weber 32/36DGEV, 4-1 header and full 2" mandrel bent exhaust, and Nissan Motorsports camshaft? I run it at 7* and it seems fine. If I set it to 5* or less it suffers alot in the midrange and up top. Quote Link to comment
datzenmike Posted July 25, 2014 Report Share Posted July 25, 2014 Single or dual plugs??? Single will always need more advance than dual plugs. If it runs strong at 7 then seven it is. Quote Link to comment
NissanEgg Posted July 25, 2014 Report Share Posted July 25, 2014 Dual plugs. Haven't tried going any higher as I am afraid it might ping. Quote Link to comment
xsdg Posted July 29, 2014 Report Share Posted July 29, 2014 The Z20 has a knock sensor, doesn't it? Quote Link to comment
datzenmike Posted July 29, 2014 Report Share Posted July 29, 2014 Ah ah ah I didn't catch that. The Z20 may run a different advance, I'll check when I get home. Otherwise follow the timing recomended on the under hood emissions sticker. Yes the Z20 does indeed have a knock sensor and ignition retard. Quote Link to comment
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