atkinson40 Posted November 29, 2009 Report Share Posted November 29, 2009 Been noticing that it takes forever for this pony to warm up. If I try to put on the manual choke it kills the engine. I have to feather the throttle for 3-4 minutes or until I see some movement on the temp gauge before it will idle by itself. I can understand that maybe I need to set the cold idle adjustment on the carb but I'm confused about why putting on the choke when its cold would kill it? Only reason I can think of if its already running super rich. Any ideas? Quote Link to comment
datzenmike Posted November 29, 2009 Report Share Posted November 29, 2009 When the choke is on, there is a linkage that sets the throttle on a stepped cam that holds it open and lets in more air. This will produce a fast idle. Without it, adding just choke will flood it and it will stall. Here's a picture of the plastic cam with steps on it: http://i138.photobucket.com/albums/q251/datzenmike/720%20stuff/carbZ24fastidleadjustLg.jpg[/img]"] Quote Link to comment
atkinson40 Posted November 29, 2009 Author Report Share Posted November 29, 2009 When the choke is on, there is a linkage that sets the throttle on a stepped cam that holds it open and lets in more air. This will produce a fast idle. Without it, adding just choke will flood it and it will stall. Here's a picture of the plastic cam with steps on it: http://i138.photobucket.com/albums/q251/datzenmike/720%20stuff/carbZ24fastidleadjustLg.jpg[/img]"] Thanks DM. My choke looks like it was originally electro/thermo but was gutted and fitted with a manual cable that comes in the cab. Your response would fit the solution for both problems. I'll check to see if the choke is setting up stepped cam. -K Quote Link to comment
ggzilla Posted November 29, 2009 Report Share Posted November 29, 2009 A proper factory manual choke will have the same 'fast idle' linkage as an automatic. Sounds like somebody gutted it, not understanding how a choke works. If you have an manual choke, engage fully to start. Push in a bit as soon as it starts. Then hold it partly engage and gradually open it fully as the engine warms up. As mike says it may not idle by itself when cold, if the fast idle cam & linkage is missing. Quote Link to comment
datzenmike Posted November 29, 2009 Report Share Posted November 29, 2009 Also try stepping down on the gas then setting the choke before starting. The throttle has to be open at least slightly for the cam to move down into position and then the throttle closes down on one of the steps. Otherwise as ggzilla says someone probably removed some parts or the linkage is just dirty and can't fall down of it's own weight. WD-40 or carb cleaner will clean it. Hold throttle open slightly and work linkage up and down to free it. Quote Link to comment
lynchfourtwenty Posted November 29, 2009 Report Share Posted November 29, 2009 thought this thread was about my truck... guess not.. :lol: Quote Link to comment
atkinson40 Posted November 29, 2009 Author Report Share Posted November 29, 2009 Also try stepping down on the gas then setting the choke before starting. The throttle has to be open at least slightly for the cam to move down into position and then the throttle closes down on one of the steps. Otherwise as ggzilla says someone probably removed some parts or the linkage is just dirty and can't fall down of it's own weight. WD-40 or carb cleaner will clean it. Hold throttle open slightly and work linkage up and down to free it. I removed the carb. Choke linkage looks to all be there and working? Also even if I hold the throttle pedal down manually while applying the choke, it still kills the motor. -K Quote Link to comment
datzenmike Posted November 29, 2009 Report Share Posted November 29, 2009 Is the choke plate closing up top when cold? Like this: OPEN http://i138.photobucket.com/albums/q251/datzenmike/720%20stuff/carb720shouldlooklikethisLarge.jpg[/img]"] CLOSED http://i138.photobucket.com/albums/q251/datzenmike/720%20stuff/carb720notlikethisLarge.jpg[/img]"] Quote Link to comment
atkinson40 Posted November 30, 2009 Author Report Share Posted November 30, 2009 Is the choke plate closing up top when cold? Like this: OPEN http://i138.photobucket.com/albums/q251/datzenmike/720%20stuff/carb720shouldlooklikethisLarge.jpg[/img]"] CLOSED http://i138.photobucket.com/albums/q251/datzenmike/720%20stuff/carb720notlikethisLarge.jpg[/img]"] Yes. Just Like That. Its controlled manually with a cable to the inside of the cab. Then a linkage that's hooked to the same shaft as the choke valve sets up the cam for the fast idle. -K Quote Link to comment
moparvwfreak Posted December 2, 2009 Report Share Posted December 2, 2009 i have been fighting with my manual choke for awhile now. my 73 is a cold blooded bitch as well untill she starts warming up. choke works fine on mine but i cant get teh choke to open again once its set. got some more adjusting to do i guess. Quote Link to comment
atkinson40 Posted December 2, 2009 Author Report Share Posted December 2, 2009 I'm going to go through the static adjustments on the rebuild kit sheet and see if I find something obvious. Mike's idea seemed right, but the choke engaged kills the engine even if I keep the motor at high revs. -Kevin Quote Link to comment
atkinson40 Posted December 2, 2009 Author Report Share Posted December 2, 2009 The Choke valve is in the same throat as the main valve. If the fast idle adjustment is meant to open the main to let in more air when the choke is set, how does the air get in? The main valve is below the choke valve. Seems the choke would block off all air and opening the main wouldn't let in more air. Is there a way that the secondary valve gets opened? -K Quote Link to comment
ggzilla Posted December 2, 2009 Report Share Posted December 2, 2009 Like was mentioned before, the choke butterfly must be opened slightly when the engine starts. Use the manual choke knob and push it in slightly. Then the "main" butterfly will get engough air for a fast idle. That's how it works. Quote Link to comment
atkinson40 Posted December 2, 2009 Author Report Share Posted December 2, 2009 Like was mentioned before, the choke butterfly must be opened slightly when the engine starts. Use the manual choke knob and push it in slightly. Then the "main" butterfly will get enough air for a fast idle. That's how it works. OK, I can fix that by setting the linkage to only close part way when I pull the knob in the cab all the way out. I'd adjusted it to close fully. Quote Link to comment
atkinson40 Posted December 2, 2009 Author Report Share Posted December 2, 2009 I put the carb back on. I wasn't able to adjust the Choke so that it only partially closed when I lulled the knob out all the way, but I can warm it up by only pulling it out part way as stated above. I've forgotten these old timers can be grumpy in the morning and need to be warmed up. I'm used to hoping in the civic and driving off. -k OK brakes are next. Quote Link to comment
ggzilla Posted December 3, 2009 Report Share Posted December 3, 2009 (edited) You should adjust it so it fully closes. Then, pump the gas once, take your foot off the gas, then turn the key. When it starts push the knob in a little. Datsuns were designed to start up and drive right off. But somebody has messed with yours. Edited December 3, 2009 by ggzilla Quote Link to comment
atkinson40 Posted December 3, 2009 Author Report Share Posted December 3, 2009 You should adjust it so it fully closes. Then, pump the gas once, take your foot off the gas, then turn the key. When it starts push the knob in a little. Datsuns were designed to start up and drive right off. But somebody has messed with yours. I have another problem that complicates the startup a bit. The fuel bowl is draining empty after sitting overnight so it takes a few cranks of the engine for it to fill up and start. Once started I need to hold the accelerator down a bit to keep it running. I'm going to monitor the startup for awhile and if it continues as it is I'll adjust the fast idle to keep it running while cold. Thanks kevin Quote Link to comment
datzenmike Posted December 3, 2009 Report Share Posted December 3, 2009 Well it can't get back in the tank so it's either leaking out onto the manifold or into the intake. That's a lot of gas to collect in there if it is. It would start up SUPER rich. Quote Link to comment
moparvwfreak Posted December 3, 2009 Report Share Posted December 3, 2009 i should look into mine and see if the bowl is draining itsself. that might be some of my problem as well. Quote Link to comment
atkinson40 Posted December 3, 2009 Author Report Share Posted December 3, 2009 (edited) Well it can't get back in the tank so it's either leaking out onto the manifold or into the intake. That's a lot of gas to collect in there if it is. It would start up SUPER rich. Where ever its ending up, I think its evaporating. It takes cranking it about the time I expect the bowl to fill for it fire. -K Edited December 3, 2009 by atkinson40 Quote Link to comment
ggzilla Posted December 3, 2009 Report Share Posted December 3, 2009 These Hitachis usually leak out of the jet plugs. Just tighten them up a little. They are just below the sight glass. You have to remove the double-nut thingy, tighten them and then replace. Quote Link to comment
atkinson40 Posted December 3, 2009 Author Report Share Posted December 3, 2009 These Hitachis usually leak out of the jet plugs. Just tighten them up a little. They are just below the sight glass. You have to remove the double-nut thingy, tighten them and then replace. Thanks ggzilla. I'll try it. It looks a bit wet around the nut I can see. Hope I can do it W/O pulling the carb again. -K Quote Link to comment
TrevDaddy Posted December 4, 2009 Report Share Posted December 4, 2009 I also have choke problems. It seems like the two screws holding the plate to the rotating arm are severely worn out and wont tighten. This allows the choke to "wobble" and not properly seat against the walls. Is there any way to remedy this problem without buying a new carb? I might have to just slap on a weber and call it a day. Quote Link to comment
ggzilla Posted December 4, 2009 Report Share Posted December 4, 2009 yes, use JB weld. Close the choke flap, tighten them about right and let the JB Weld harden for 24 hours. Quote Link to comment
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