Braden Posted August 22, 2009 Report Share Posted August 22, 2009 just spent the last 5 hours rebuilding my hitachi carb for my 620, truck starts right up then idles at about 3100 rpm, i have adjusted the idle needle according to the directions, seat lightly then 2 to 2.5 turns outward, what the hell is wrong with it? i adjusted the float also, the other adjustment screw that controls the throttle blades i adjusted when i had the carb off, i turned it to where the throttle blade was barely opened, please help Quote Link to comment
Braden Posted August 22, 2009 Author Report Share Posted August 22, 2009 could it have something to do with the fast idle? i dont know where to start with adjusting the fast idle Quote Link to comment
Braden Posted August 22, 2009 Author Report Share Posted August 22, 2009 here it is all together and on the truck, look at the 2 lines on the left side of the carb, one is blocked off and one is spliced, could i have gotten these mixed up, what is their purpose anyways Quote Link to comment
datzenmike Posted August 22, 2009 Report Share Posted August 22, 2009 The fast idle is set during the rebuild. Check the choke is off when warmed up or just push it open and hold open with your finger and rev the motor slightly. The fast idle should disengage. This: http://i138.photobucket.com/albums/q251/datzenmike/720%20stuff/carbZ24idlestepLg.jpg[/img]"] is the fast idle cam. If you look along the bottom there are steps like stairs. The choke on linkage will pull the cam into position and set the idle against one of these 'steps'. http://i138.photobucket.com/albums/q251/datzenmike/720%20stuff/carbZ24fastidleadjustLg.jpg[/img]"] Here you can see the set screw that rides on one of the 'steps' of the fast idle cam. When the choke is in the off position and the throttle opened, the cam will drop out of the way of it's own weight and the set screw will drop off the steps and allow the throttle to return to the idle position. Check also that the secondary throttle plate is closing fully. With engine off look down the barrel on the driver's side of the carb. Way down at the bottom you will see a plate that should be closed fully. The upper larger hole with the closed brass plate is the secondary barrel. Here is the linkage that opens the secondary. The round cone shaped thing is the vacuum diaphragm. If you suspect that the secondary is partially open try pulling down on the linkage. I had a very high idle on my Z24. Tried everything, all the idle adjustments and mixture were set and checked but would not idle below 2,200. While working on something unrelated, I pushed up and down on the diaphragm linkage, the secondary clicked shut and the idle dropped to normal. Just stuck from sitting I guess. Quote Link to comment
MAG58 Posted August 22, 2009 Report Share Posted August 22, 2009 If you go below 3k, will it just die? Can you get it below 3k? If it just dies, check the anti-deiseling valve. Otherwise, I'd try adjusting the electric choke which can be done by lostening up the retaining strap and rotating. Quote Link to comment
Braden Posted August 22, 2009 Author Report Share Posted August 22, 2009 no i cant get it below 3000, i cant tune it anymore tonight i live right beside an old widow and i dont want to piss her off, im running straight header, as far as all of the linkage i put it back exactly how it was before i took it off the truck, both throttle paltes are closed on startup, one of them is probably partially open because i set the idle screw, on startup maybe one of them is opening up alot? what could cause that? i cant get the float to fill up to the dot, the gasket for the float window is leaking, brand new junk, didnt leak a bit with the old gasket, anyways i tightened up the window srews hoping to get it to seal, and took off the distributor and cranked it over for a few seconds and i still cant get the float to fill up fully, what the? Quote Link to comment
Braden Posted August 22, 2009 Author Report Share Posted August 22, 2009 bump i need to get my truck on the road!!!! Quote Link to comment
MAG58 Posted August 22, 2009 Report Share Posted August 22, 2009 Your float level is set too high, take the little tab that sits under the float valve and bend it down. Quote Link to comment
Braden Posted August 22, 2009 Author Report Share Posted August 22, 2009 is that what is causing the super high idle? Your float level is set too high, take the little tab that sits under the float valve and bend it down. Quote Link to comment
Orange620 Posted August 22, 2009 Report Share Posted August 22, 2009 The forward vacuum tube is for the distributor. The other is for a multitude of smog stuff. Plug it. Does Kentucky have smog checks. Why is all that crap still on your engine? Quote Link to comment
Braden Posted August 22, 2009 Author Report Share Posted August 22, 2009 no smog checks here, its still on there for no reason at all, other than i have anothermotor that has it off that i am going to swap sooner or later Quote Link to comment
Cuts metal like mad Posted August 22, 2009 Report Share Posted August 22, 2009 shouldn't the choke be open when theres no power to it? Quote Link to comment
Braden Posted August 22, 2009 Author Report Share Posted August 22, 2009 yeah you would think so, shit i dont know i need help guys, really bad i need to get my truck on the road, i cant afford to drive my full size ttruck back and forth to college this week, i have 23 dollars to my name! shouldn't the choke be open when theres no power to it? Quote Link to comment
Braden Posted August 22, 2009 Author Report Share Posted August 22, 2009 actually the choke should always be on untill the motor heats up when the engine heats up the thermostat opens the choke up, Quote Link to comment
Braden Posted August 22, 2009 Author Report Share Posted August 22, 2009 here is the deal, with the engine off and cold the linkage is sitting on the "steps" and the choke is closed, ok now i move the throttle back and forht, it moves easily and the when i return it to the down position it still rests on the steps, i guess that is normal since the engine is cold, that seems to be working fine, now i can open the throttle up and hold the choke open by hand and return the throttle to down, its is now off the "steps" continue to hold the choke open and move the throttle and it will stay off the steps since i have the choke held open acting as the engine is warm right? im positive i have no vacumm leaks as i cleaned and scraped all gasket mating surfaces and used all new gaskets, i need to re adjust my float as its not fillingup the float chaMBER could the float thing be the problem? i dont see how Quote Link to comment
LenRobertson Posted August 22, 2009 Report Share Posted August 22, 2009 Float level question first - The fuel level should be at the center of the glass window. There is usually a white dot on the glass, but it isn't always easy to see. Check this level and let us know what you find. If you have the engine running, with the choke completely open, and you move the linkage off the fast idle steps, does the engine more or less idle (or at least run a lot slower)? I'm trying to understand if you have a problem with it not coming off the fast idle cam. If you manually move it off the cam and the engine won't run, then it may be something mentioned before, like the anti-dieseling solenoid. Len Quote Link to comment
Braden Posted August 22, 2009 Author Report Share Posted August 22, 2009 what the hell guys please help me out, ok the damn float gasket leaks all to hell so does the gasket between the top part of the carb and the second part, i put rtv on the float window gasket, hopefully that stopped that leak, im clueless guys, im getting very frustrated, the old dirty carb worked a hell of a lot better, the damn thing now revs to 4500!!!!!! what the fuck? help me out carb gurus!!!!! Quote Link to comment
Buzzbomb Posted August 22, 2009 Report Share Posted August 22, 2009 Why did you rebuild that carb? It looks brand new to me? Did you trade in your old carb or do you still have it? If you still have it, why not take the new one off and put the old one back on for now? I think Datzenmike is right...It sounds like the secondary plate or diaphragm is getting hung up. Follow his instructions and make sure its closed. I've had this happen before. Open the the throttle halfway, and push down on the diaphragm linkage. Did you forget the throttle return spring? Is the throttle cable getting hung up? Quote Link to comment
Braden Posted August 22, 2009 Author Report Share Posted August 22, 2009 the float is filling up although i have not verified it is to the dot, it doesnt matter what i move, the choke, the throttle, it stays around 4500 rpm, might go up or down a feww hundred rpm, but i start the truck then waaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaputputwaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa move some shit then waaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa all at 4500, im about to go get another kit and rebuild the fucker again, the gaskets they sent are shit, dont buy a walker kit, lets say it is the anit dieseling solenoid, what would that do Float level question first - The fuel level should be at the center of the glass window. There is usually a white dot on the glass, but it isn't always easy to see. Check this level and let us know what you find. If you have the engine running, with the choke completely open, and you move the linkage off the fast idle steps, does the engine more or less idle (or at least run a lot slower)? I'm trying to understand if you have a problem with it not coming off the fast idle cam. If you manually move it off the cam and the engine won't run, then it may be something mentioned before, like the anti-dieseling solenoid. Len Quote Link to comment
Braden Posted August 22, 2009 Author Report Share Posted August 22, 2009 (edited) its the same one, i spent about 5 hours cleaning it and rebuilding it, basically i had an old hitachi that was dirty and the choke didnt wrok right and it had a bad accelerator pump, so i rebuilt it so i can drive it instead of my silverado, i love 30 mpg not 15, all of the linkage and springs and what have you are in the correct position, i followed the directions on the carb worksheet, put every jet back in the same hole and put every scvrew back in the same hole basically i just disassembled cleaned really good and reassembled replacing everything i could. Why did you rebuild that carb? It looks brand new to me? Did you trade in your old carb or do you still have it? If you still have it, why not take the new one off and put the old one back on for now? I think Datzenmike is right...It sounds like the secondary plate or diaphragm is getting hung up. Follow his instructions and make sure its closed. I've had this happen before. Open the the throttle halfway, and push down on the diaphragm linkage. Did you forget the throttle return spring? Is the throttle cable getting hung up? Edited August 22, 2009 by ghettobraden Quote Link to comment
Braden Posted August 22, 2009 Author Report Share Posted August 22, 2009 ok i just fired it up and then shut it off looked down the secondary and there was raw fuel sitting on top of it, the float is full perfect with the dot, while it was running i jumped out and move the throttle trying to disengage it and it just revved higher Quote Link to comment
Braden Posted August 22, 2009 Author Report Share Posted August 22, 2009 ok i think that the float is filling up and dumping all of its fuel for some reason? maybe a gasket leaking could cause this? Quote Link to comment
Braden Posted August 22, 2009 Author Report Share Posted August 22, 2009 ok the kit came with 2 gaskets that go inbetween the top third of the carb and the second third of the carb, i installed both gaskets, i know it leaks aroud there because i can pour gas down the carb and it runs out all around there, i am going to take it back apart and only put one of the gaskets in there, i think the kit came with 2 gaskets to fix different models of the carb. update now the enging is hot and the choke opened and now its idling at about 2000 instead of 4500, thought or comments would be good Quote Link to comment
Cuts metal like mad Posted August 22, 2009 Report Share Posted August 22, 2009 sounds like just that... the rebuild kit was garbage, OR was done wrong. Can't be the anti-dieseling solenoid, it is just an electrically operated idle jet that closes when you turn off the ignition, so then the fuel is cut and you don't get run on... Quote Link to comment
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