rclayton12 Posted April 11, 2006 Share Posted April 11, 2006 I have a '73 240z that I have just converted from the flat top carbs, to Ztherapy S.U.s and after I drive the car for about 20 minutes, it will backfire, and run a little while after I have turned the key off I think it is called Diesel-ing. I had the same problem with the flat tops, and was hoping that the S.U.s would fix it. Any help would be appreciated. Quote Link to comment Share on other sites More sharing options...
TheNeedForZ Posted April 11, 2006 Share Posted April 11, 2006 I'd say the spark plugs is giving you the problem, have you pulled the spark plugs to see if they are dirty or check their heat range? Might want to use plugs in the colder range. read about heat range of spark plugs here : http://en.wikipedia.org/wiki/Spark_plugs#heat_range Quote Link to comment Share on other sites More sharing options...
Guest beandip Posted April 11, 2006 Share Posted April 11, 2006 I agree with rclayton12 . In addition ZT often installs SM needles check to see if this is the case . If so buy a set of 54s , SMs are way to rich and this could cause what you are describing . Also double check the timing and set a 10 degrees BTDC . If the timing is retarded it also will cause the described problem . Quote Link to comment Share on other sites More sharing options...
Silent Posted April 11, 2006 Share Posted April 11, 2006 lean out the carbs. or back down the timing. mine does this sometimes, i usually just adjust carbs and it's happy for a while. or stab the throttle real quick before shutting it off Quote Link to comment Share on other sites More sharing options...
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