I have read through and searched the forum, but I can not find anyone with the same issue as me. I am the second owner of my 84 720 2.4z, my carb decides to have the choke stick closed so the engine runs extremely rich and it is become more and more common, almost everyday. It is the to the point I can not un-stick it and when I shut the engine off, the engine almost restarts itself due to so much fuel left over. Please help, I would like to save the carb if possible rather than spend the money on a weber if possible.
Thanks!!
Carb Issue
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84Datsun720
- Posts: 12
- Joined: Thu Feb 17, 2011 10:54 pm
- Car: 1984 Datsun/Nissan 720 SC LB
Re: Carb Issue
A sticking choke is usually because of carbon build up and dirty linkages etc... It can also be because of bent linkage arms. have you cleaned the carb and the choke mechanisms really well yet? also try using some wd40 on the linkages and the choke shaft to see if it improves. Try removing the electric choke thermostat and see if it's broken and check for freedom of movement, if anything is binding, you'll need to find where it's binding and then you can fix by slightly bending whichever arm so it doesn't hit anything in it's range of travel. Check the choke plates to see if they're rubbing against the sides of the inside of the carb as well.
The choke mechanism on the stock carb and on the weber carbs are very simple so you should be able to torubleshoot and fix it pretty easily, or you can lock it open while waiting on parts if the choke thermostat is the culprit. There's also a vacuum operated choke pull off mechanism that can go bad, this one is what pulls the choke off when you accelerate before the engine is warmed up, it's also connected to linkage arms that may be bent. The choke linkage arms are pretty tough, but can get bent by improper assembly or disassembly so they are worth checking for freedom of movement.
If you can't find the problem and need this as your daily driver, disconnecting the choke linkage at the choke shaft and locking it open is better than running it with the choke sticking shut until you find the problem, you'll just have to pump the throttle to get it to start and keep reving it while it's warming up or until you get on the highway. It's always best to fix it, but you can lock it open as a last resort.
As far as carbs go, the 32/36 weber DGEV will give you better performance, smoother idle and running, and better gas milage, while the 38/38 outlaw carb will give you an extra 10 hp or so while keeping the gas milage about the same as stock, so they are definitely worth looking into. There are other carbs that'll work that are much less expensive like the Holley 5200 series carbs off an early 70's ford pinto which is the exact same carb as a Weber 32/36 DFAV and it's a perfect mirror image of the DGEV series carbs meaning everything is in the opposite location but they perform identically and can usualy be had for about $75, you'll still need to buy a weber adapter plate but it'll save you about $150 or so over buying the DGEV model. I'm running a Holley 5200 on mine and it performs dead smooth after putting the right jets in it.
The choke mechanism on the stock carb and on the weber carbs are very simple so you should be able to torubleshoot and fix it pretty easily, or you can lock it open while waiting on parts if the choke thermostat is the culprit. There's also a vacuum operated choke pull off mechanism that can go bad, this one is what pulls the choke off when you accelerate before the engine is warmed up, it's also connected to linkage arms that may be bent. The choke linkage arms are pretty tough, but can get bent by improper assembly or disassembly so they are worth checking for freedom of movement.
If you can't find the problem and need this as your daily driver, disconnecting the choke linkage at the choke shaft and locking it open is better than running it with the choke sticking shut until you find the problem, you'll just have to pump the throttle to get it to start and keep reving it while it's warming up or until you get on the highway. It's always best to fix it, but you can lock it open as a last resort.
As far as carbs go, the 32/36 weber DGEV will give you better performance, smoother idle and running, and better gas milage, while the 38/38 outlaw carb will give you an extra 10 hp or so while keeping the gas milage about the same as stock, so they are definitely worth looking into. There are other carbs that'll work that are much less expensive like the Holley 5200 series carbs off an early 70's ford pinto which is the exact same carb as a Weber 32/36 DFAV and it's a perfect mirror image of the DGEV series carbs meaning everything is in the opposite location but they perform identically and can usualy be had for about $75, you'll still need to buy a weber adapter plate but it'll save you about $150 or so over buying the DGEV model. I'm running a Holley 5200 on mine and it performs dead smooth after putting the right jets in it.