g9m3c Posted November 19, 2008 Share Posted November 19, 2008 Alright guys, the float is stuck in my front carburetor. It runs, but very badly. Haha, it runs a full stream of gas out the vent tube, so I'm pretty sure that's the problem. What's the easiest/quickest way to get it unstuck? Will I have to take the carb off? I hope not. Any help at all is appreciated! -Grant EDIT- It's a '74 Datsun 260Z. Stock. Quote Link to comment Share on other sites More sharing options...
g9m3c Posted November 19, 2008 Author Share Posted November 19, 2008 Does anyone know? I'm hoping to start working on this in the morning. Quote Link to comment Share on other sites More sharing options...
240z!!! Posted November 19, 2008 Share Posted November 19, 2008 it should be in a hayne's manual but if its roundtop su's you should be able to take the four screws that hold on the top of the bowl it shouldnt take more than 10 min to get it off...and you dont have to take the carb off Quote Link to comment Share on other sites More sharing options...
Austin240Z Posted November 19, 2008 Share Posted November 19, 2008 it should be in a hayne's manual but if its roundtop su's you should be able to take the four screws that hold on the top of the bowl it shouldnt take more than 10 min to get it off...and you dont have to take the carb off True, it's easy to take off. I had a stuck float on the rear carb when I first got my 240, a quick light tap on the top of the bowl fixed that. I didnt even have to take the top of the bowl off. Quote Link to comment Share on other sites More sharing options...
g9m3c Posted November 19, 2008 Author Share Posted November 19, 2008 The top of the bowl? Isn't the bowl on the bottom of the carb? Quote Link to comment Share on other sites More sharing options...
240z!!! Posted November 19, 2008 Share Posted November 19, 2008 depending on what carbs you have? are they roundtop or flattop su's or an aftermarket brand? Quote Link to comment Share on other sites More sharing options...
g9m3c Posted November 19, 2008 Author Share Posted November 19, 2008 They're the factory 260Z carbs. Flat top I guess? The top of the carbs are shaped like a cylinder, round with a flat top. The middle of them have a dampener assembly. Quote Link to comment Share on other sites More sharing options...
blue72 Posted November 19, 2008 Share Posted November 19, 2008 I could only find one decent picture online of the carbs, and it doesn't help much. Here, this page at least describes most of the differences between the Flat Tops and the earlier Round Top SU's. http://www.zparts.com/zptech/tech_tips/izccposts/su_differences.htm Better yet, go over to autozone.com and look at the repair guide for your car. It has a section (fuel system - carburetted fuel system 70-78) which is pretty comprehensive for 70-74 SU's. It shows carb components, how to adjust the float on your carbs, how to set fast idle, and how to get at the float chamber itself on your Flat Top carbs. They even sell replacement floats if need be. You could even try downloading the FSM from xenons30.com too. It shows cutaway views of the carbs, which seven screw to remove to access the float on the bottom, how to check the power valve and a troubleshooting table. The Fuel System section also shows which vacuum hoses go where, how to check each component, like the idle compensator, and it even has sections dealing with the mechanical and electric fuel pumps which may answer the questions you had earlier this week about them. Quote Link to comment Share on other sites More sharing options...
rxsleeper Posted November 19, 2008 Share Posted November 19, 2008 look here: http://www.ztherapy.com/ You can find a picture of the 260 carbs under the heading of "Boat Anchor" Call Bruce and he can help you with the carbs, but probably not much help with the flat tops. If you can find a set of round tops they are easier to work on and to make run right on the Z. Quote Link to comment Share on other sites More sharing options...
g9m3c Posted November 19, 2008 Author Share Posted November 19, 2008 Thanks for the help guys. Now I have another problem though. I took the carb off and sure enough, the float was stuck. I got that fixed and got the carb back on and everything assembled. Now it won't start at all. Not even a sputter from one cylinder. I took the coil wire off of the coil, and it's sparking. I'm lost now. EDIT: Just went back out and tried it agin. Now it sputters every couple of revolutions or so. I'm still lost. Quote Link to comment Share on other sites More sharing options...
Daeron Posted November 20, 2008 Share Posted November 20, 2008 how are the chokes working?? Not much of a carb man here, but im getting a baptism by fire with this junker 240 we're getting running for me. Can you get it to start with someone (mostly) choking off the front intakes of the carbs with their hands? Pull a plug after trying to start and make sure it smells like fuel and is wet... If so, then you aren likely getting too much fuel. If not, try pouring a little fuel into the carburetor before you try to crank it, or get some starter fluid. If that starts it, you aren't getting enough fuel. Simple, I know, but its about my limits with carbs. Quote Link to comment Share on other sites More sharing options...
g9m3c Posted November 20, 2008 Author Share Posted November 20, 2008 how are the chokes working?? Not much of a carb man here, but im getting a baptism by fire with this junker 240 we're getting running for me. Can you get it to start with someone (mostly) choking off the front intakes of the carbs with their hands? Pull a plug after trying to start and make sure it smells like fuel and is wet... If so, then you aren likely getting too much fuel. If not, try pouring a little fuel into the carburetor before you try to crank it, or get some starter fluid. If that starts it, you aren't getting enough fuel. Simple, I know, but its about my limits with carbs. Yea, we've already tried all of that. The only way we can get it to start is by holding the accelerator all the way down, and then it barely idles. My dad's been helping me, and he has 30+ years of automotive experience. Still nothing. Quote Link to comment Share on other sites More sharing options...
Daeron Posted November 20, 2008 Share Posted November 20, 2008 how immediate are your swap plans? if you are really on the ball about it, you *might* be able to find someone local with some real SUs they might loan/"rent" you to use as long as you're using the L-gata? Quote Link to comment Share on other sites More sharing options...
blue72 Posted November 20, 2008 Share Posted November 20, 2008 Have you verified the timing and checked that the spark plugs are installed in the right firing order? You never know. Quote Link to comment Share on other sites More sharing options...
g9m3c Posted November 20, 2008 Author Share Posted November 20, 2008 Have you verified the timing and checked that the spark plugs are installed in the right firing order? You never know. Yep, that's the first thing we did. Quote Link to comment Share on other sites More sharing options...
Dayz Posted November 20, 2008 Share Posted November 20, 2008 Dismantle it again! Maybe you have a piece of dirt in it...it doesn't take much. Check your vacuum as well, I remember trying to start them one time without the hoses plug in, wasted 2 hours assembling disassembling carbs to find out it was taking air from the balance tube. Same theory of finding an elec. gremlin for hours to find out it was a fuse! Gas, fire at the right time with proper amount of air will get you going! Good luck Dayz Quote Link to comment Share on other sites More sharing options...
Daeron Posted November 20, 2008 Share Posted November 20, 2008 So, you have to hold the accelerator down all the way to get it to even TRY to start. That means too much fuel is still getting in for some reason, or not enough at ALL. Does it start when you choke the fronts of the carbs off by hand?? If so, then your hands help increase the vacuum pressure action in the carb, sucking more fuel through the jet, and your problem is that your carbs aren't getting you enough fuel. If NOT, then you are definitely still getting too much fuel in the bowls. Just re-analyzing and re-stating your situation to see if it helps jar anything loose in your brain. Quote Link to comment Share on other sites More sharing options...
g9m3c Posted November 21, 2008 Author Share Posted November 21, 2008 Well, after messing with it again today, I've decided to just rebuild the carbs. We got them taken off today, and I'm going to pain stakingly rebuild them to perfection so I'll know they're right. I'm also taking the smog pump off while I'm at it. Where the other end of the smog pump hoses connect to the engine, do I just need to cap those off? Quote Link to comment Share on other sites More sharing options...
Daeron Posted November 21, 2008 Share Posted November 21, 2008 ahhhh.. I cannot tell you the last time I saw an SU setup complete with smog stuff, but I know that the air injection tube going into the exhaust manifold is usually crimped off, and there ARE a few hard lines that are left vacant and open afterwards when all the anti-pollution equipment is removed. HTH Quote Link to comment Share on other sites More sharing options...
Austin240Z Posted November 22, 2008 Share Posted November 22, 2008 The top of the bowl? Isn't the bowl on the bottom of the carb? OH... flat tops... ouch. Most people throw those away, or if they keep them.. they're used as door stops or paper weights. Thanks for the help guys. Now I have another problem though. I took the carb off and sure enough, the float was stuck. I got that fixed and got the carb back on and everything assembled. Now it won't start at all. Not even a sputter from one cylinder. I took the coil wire off of the coil, and it's sparking. I'm lost now. EDIT: Just went back out and tried it agin. Now it sputters every couple of revolutions or so. I'm still lost. Could be that the float is stuck at the TOP now and is not allowing much gas into the bowls. Getting stuck at the bottom would have caused your earlier gas going everywhere problem. If it got stuck once, it could have easily happened again. Well, after messing with it again today, I've decided to just rebuild the carbs. We got them taken off today, and I'm going to pain stakingly rebuild them to perfection so I'll know they're right. I'm also taking the smog pump off while I'm at it. Where the other end of the smog pump hoses connect to the engine, do I just need to cap those off? Unless you're trying to keep it all original and 100% stock, I wouldn't bother. The flat tops are in a word, terrible. You will get much better performance out of the 240Z round top SU's. If I didn't need some of the parts off my spare set still, I would have offered you mine. Quote Link to comment Share on other sites More sharing options...
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