dat*blu*73 Posted February 18, 2014 Report Share Posted February 18, 2014 hi i'm new here and new to 620s bought a 73 a few months ago.. did'nt start at first but now it does.. problem is rebuilt the hitachi but now it wont idle and backfires bad .. did ajustments to carb but still does not work right any suggestions would be helpful.. Quote Link to comment
datzenmike Posted February 18, 2014 Report Share Posted February 18, 2014 Out the carb or the tail pipe????? Quote Link to comment
dr.feltersnatch Posted February 18, 2014 Report Share Posted February 18, 2014 are you running points? backfiring through exhaust or carb? Quote Link to comment
ohmrchristopher Posted February 18, 2014 Report Share Posted February 18, 2014 actually i'm gonna jump on here too. 1973, dual points, new Weber, out the carb. I assume its because its cold and I haven't let it warmed up? 10 min I presume? Quote Link to comment
datzenmike Posted February 18, 2014 Report Share Posted February 18, 2014 Lack of choke when cold will do this. Needs to be richer mixture when cold because the internal parts aren't hot enough to vaporize the fuel droplets. Effectively it's running lean. The backfire through the carb is a lean backfire. My L18 automatic is set right. Fire up on cold day and put in gear an step on the gas it backs up. Put in drive and away it goes. Nissan did not design them to run like shit in the cold. The only difference in running when the motor is cold is a slight lack of power. Quote Link to comment
dat*blu*73 Posted February 18, 2014 Author Report Share Posted February 18, 2014 out the pipe Quote Link to comment
datzenmike Posted February 18, 2014 Report Share Posted February 18, 2014 Probably electrical. Interrupted spark, the unburned gas goes into the exhaust pipe and it lit off as soon as the spark returns. Could be dirty fouled plugs, bad wires, old dizzy cap but most likely worn out points or a loose wire on the coil. Quote Link to comment
ggzilla Posted February 18, 2014 Report Share Posted February 18, 2014 Another common cause is a backyard carb rebuild. Loose jet can do it. You may want to re-assemble the carb. Quote Link to comment
dat*blu*73 Posted February 18, 2014 Author Report Share Posted February 18, 2014 thanks for the input gonna try a few things and i'll let you know what works.. Quote Link to comment
ohmrchristopher Posted February 18, 2014 Report Share Posted February 18, 2014 I have the auto choke wired to the coil (+), unless this is wrong. Its what I have seen on most Weber swap threads. I had tuned it up in the summer when i installed it. 500 RPM idle and just purrring. I dont think I would have to adjust this come winter? Quote Link to comment
ggzilla Posted February 18, 2014 Report Share Posted February 18, 2014 ohmrchristopher, why are you asking about your choke in datblu73's backfire Topic? 1 Quote Link to comment
CorAce Posted February 18, 2014 Report Share Posted February 18, 2014 out the pipe Make sure your timing is set correctly as well. Quote Link to comment
Laecaon Posted February 18, 2014 Report Share Posted February 18, 2014 I was backfiring out the carb and pipe once. Ignition condenser died. Stupid points. Quote Link to comment
ohmrchristopher Posted February 19, 2014 Report Share Posted February 19, 2014 ohmrchristopher, why are you asking about your choke in datblu73's backfire Topic? Cause I was having the similar issue. Mike answered it. Quote Link to comment
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