Sin720 Posted January 17, 2014 Report Share Posted January 17, 2014 So I've replaced my plugs and wires dizzy cap and rotor. Cap was melted on one terminal thought it was my issue but my rpms keep going up and down. I figured it had to be my carb as I had adjusted the throttle cable to be able to drive it. Also has an issue recovering back to idle after letting off the gas. Any suggestions? Quote Link to comment
willz Posted January 18, 2014 Report Share Posted January 18, 2014 check vacuum lines... I wouldn't be surprised if you had a crack somewhere going to your distributor check fuel pressure, your filter might be clogged, your pump may be crapping out (although both of those are unlikely) are you running an electronic dizzy or points? Quote Link to comment
ggzilla Posted January 18, 2014 Report Share Posted January 18, 2014 Cap melted - did replacing it change the symptoms at all? Uneven idle is a sign the mixture is wrong. After making sure the hoses and vacuum accessories are good then the idle air/fuel mixture should be set., Quote Link to comment
Sin720 Posted January 18, 2014 Author Report Share Posted January 18, 2014 check vacuum lines... I wouldn't be surprised if you had a crack somewhere going to your distributor check fuel pressure, your filter might be clogged, your pump may be crapping out (although both of those are unlikely) are you running an electronic dizzy or points? Its a points dizzy, I went through all the vaccum lines yesterday had 1 split so I cut off the split part and put it back on. Not sure about the fuel as I just bought the truck last saturday And it was running rough then so first thing i did was put seafoam in the tank and filled her up. Also bought a can of carb cleaner and sprayed it out. Still no change, Just to get it to run I had to adjust the idle from the screw closed to the throttle cable then at the idle that was capped I turned it down to the point where it was going to cut off and then adjusted in up a lil. Cap melted - did replacing it change the symptoms at all? Uneven idle is a sign the mixture is wrong. After making sure the hoses and vacuum accessories are good then the idle air/fuel mixture should be set., Yes as I couldnt tell this was happening until after I did the distributor cap wires plugs and rotor. Quote Link to comment
dr.feltersnatch Posted January 18, 2014 Report Share Posted January 18, 2014 Also has an issue recovering back to idle after letting off the gas. Any suggestions? check float level Quote Link to comment
Driftease Posted January 18, 2014 Report Share Posted January 18, 2014 In my experience wandering idle is usually lean condition a small particle will plug idle jets easily. How is your tip in as you start to accelerate if it hesitates it is probably the idle jet but could still be something stuck in the needle jet. Quote Link to comment
Sin720 Posted January 19, 2014 Author Report Share Posted January 19, 2014 check float level I dont know how to check or adjust the float =/ Not too familar with tuning carbs In my experience wandering idle is usually lean condition a small particle will plug idle jets easily. How is your tip in as you start to accelerate if it hesitates it is probably the idle jet but could still be something stuck in the needle jet. Yeah every once in a while when I'm accelerating it feels weak and bogs. The fuel filter is in the tank right? Would it be a bad idea to put a inline filter on it in the future? I was hoping the sea foam would help flush everything out. I have a lot of condensation in my exhaust also. I dont think the genus who had it last had the weep hole on the bottom of the muff. Idk I have a foot and a half of spray from my exhaust every start up. I advanced my distributor a bit and its doing a lot better. Also no matter what way I turned my distributor the car would adjust the timing and tune itself for the most part. Quote Link to comment
dr.feltersnatch Posted January 19, 2014 Report Share Posted January 19, 2014 this thread will help you get familiar with the carb. http://community.ratsun.net/topic/33847-diy-hitachi-carb-rebuild-pic-heavy/ and this one tells you how to set your float http://community.ratsun.net/topic/17814-hitachi-float-adjust/ Quote Link to comment
Fat510 Posted January 19, 2014 Report Share Posted January 19, 2014 Pics of your setup? Quote Link to comment
Driftease Posted January 19, 2014 Report Share Posted January 19, 2014 I dont know how to check or adjust the float =/ Not too familar with tuning carbs Yeah every once in a while when I'm accelerating it feels weak and bogs. The fuel filter is in the tank right? Would it be a bad idea to put a inline filter on it in the future? I was hoping the sea foam would help flush everything out. I have a lot of condensation in my exhaust also. I dont think the genus who had it last had the weep hole on the bottom of the muff. Idk I have a foot and a half of spray from my exhaust every start up. I advanced my distributor a bit and its doing a lot better. Also no matter what way I turned my distributor the car would adjust the timing and tune itself for the most part. Seafoam is good stuff but if your fuel lines or pump is old little bits or rubber will brake loose and get stuck in the jets. You should avoid driving it till you can rebuild the carb or have it rebuilt, a lean condition will destroy an engine very quickly especially if your timing is off. If it is all stock tuning should not be necessary just needs to be perfectly clean, float level checked, inlet screen on carb checked/cleaned and the timing set per factory spec. If you find black stuff in your inlet screen plan to repace all rubber hose and possibly the fuel pump. Quote Link to comment
Sin720 Posted January 19, 2014 Author Report Share Posted January 19, 2014 I planned on doing all fuel lines and brake lines asap. The truck was sitting a few months before my boss got it and I bought it from him. The truck will be taken down to the frame and fully restored. I can't let it sit though as its now my daily driver. Me and the gf was sharing a car and it was quite stressful. When on the highway or driving I have no issues. Only when returning back to idle goes it seem to have issues. Since I advanced the dizzy I accelerate a lot better and even the tires actually burn rubber it no longer bogs Quote Link to comment
Driftease Posted January 19, 2014 Report Share Posted January 19, 2014 Advancing your dizzy is a very bad idea until you are sure it is fueled adequately even with a lower compression engine combustion temp drastically increases as the air to fuel ratio increases which can cause detonation, overheating, and piston failure. If you have to drive it avoid hard acceleration and put your timing back to factory spec till you get the carb or vacuum problem worked out. There is a dashpot on the carb that slows the closing of throttle on decel you can check to see if it is working by bliping the throttle and watch to see if it closes most of the way fast then slows down before returning to idle position. Quote Link to comment
Sin720 Posted January 20, 2014 Author Report Share Posted January 20, 2014 Yeah I cant find any other vacuum leaks then that one hose. I still hear whistle but i cant find anything I traced through all the vacuums. I really think I just need to rebuild my carb since the truck was sitting for so long. Are the servos for the heating vacuum controlled? Quote Link to comment
Sin720 Posted January 22, 2014 Author Report Share Posted January 22, 2014 My intake gasket was the leak needed replaced and now its running great thanx guys. However my engine still has a harsh turn off. Quote Link to comment
ggzilla Posted January 22, 2014 Report Share Posted January 22, 2014 Good work. Now put your timing back where it belongs and maybe the run-on will go away. Regarding engine run-on, search for the recent discussions on it. There are many possible causes. Quote Link to comment
Driftease Posted January 22, 2014 Report Share Posted January 22, 2014 Run better gas, Shell or Chevron is all i will run. Quote Link to comment
Sin720 Posted January 22, 2014 Author Report Share Posted January 22, 2014 Good work. Now put your timing back where it belongs and maybe the run-on will go away. Regarding engine run-on, search for the recent discussions on it. There are many possible causes. I already did, its still doing it. I think its carbon build up... Saw a lot on my plugs. It really needs the rebuild. I was gonna use a mizumo rebuild kit. Any kits you guys recommend Quote Link to comment
Sin720 Posted January 22, 2014 Author Report Share Posted January 22, 2014 How come the second butterfly valve on my carb doesn't open? Quote Link to comment
ggzilla Posted January 23, 2014 Report Share Posted January 23, 2014 Because it's not supposed to. 720 has a vacuum-secondary carburetor. Quote Link to comment
Sin720 Posted January 23, 2014 Author Report Share Posted January 23, 2014 Yeah I figured that out. However I don't understand the purpose of that..... Quote Link to comment
Driftease Posted January 24, 2014 Report Share Posted January 24, 2014 The vacuum secondary purpose is to help keep the air velocity high through the venturi besides if there is no vacuum to operate the secondary there is no restriction so the secondary is not needed. The secondary is set much richer than the primary to aid in acceleration Quote Link to comment
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