Haven't found this discussed elsewhere, so wondering if anyone has any input on rebuilding the carburettor in an L28.
Background is that I've had occasional problems with misfires, funny engine pop and squeaks, rough running, suffocating on power application and so forth. Cleaning plugs generally fixes most misfires, but lately I've had to dowse the air intake in carby cleaner to get things running right again. Now carby cleaner will only work for a short time, and not entirely perfectly either. Things are particularly bad on inclines. I figure its time for a carby rebuild.
I've never done this, but Lay80n's done a few so I'll be hitting him up for a hand. Just wondering if anyone can provide some specific pointers:
1. Is a carby rebuild likely to help much?
2. What's a kit likely to cost me?
3. It is worth looking for partial/complete rebuild kit, or even a new carby?
4. What specific things should I look for as it comes apart?
5. Any other pointers?
A few extra terms for the search engine: MQ, petrol, carbie, carburetor, carb, carbi, carburretor, carburettor, carbeuretor, carbeurettor.
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Carburettor Rebuild on L28
Carburettor Rebuild on L28
* Nothing is foolproof to a sufficiently talented fool *
Well, the problems you describe might be electrical as well, but it won't cost you much time/money to rebuild the carby, and won't hurt.
Kit shouldn't cost more then $20-30, they are a very simple carby.
I'd consider looking at replacing the standard carby with something else, weber or holley - will chew more petrol, but apparantly a nice increase in power at the same time ! (Someone suggested the weber off an 3.xL XF falcon is a good match).
See if you can't get another cluster from the wreckers to fix your oil pressure problem - forgot to tell you on msn, but that is 99% chance of what your oil pressure problems will be: a faulty gauge.
Kit shouldn't cost more then $20-30, they are a very simple carby.
I'd consider looking at replacing the standard carby with something else, weber or holley - will chew more petrol, but apparantly a nice increase in power at the same time ! (Someone suggested the weber off an 3.xL XF falcon is a good match).
See if you can't get another cluster from the wreckers to fix your oil pressure problem - forgot to tell you on msn, but that is 99% chance of what your oil pressure problems will be: a faulty gauge.
I bought a kit and spent a night re building my carb it was very messy and still did not work, I then bought a holley spent $100 getting 2 mechanics to stuff around with it only to tell me the addaptor plate provided will never fit .
In the end I paid $350 and got an exchange recond carb and the car runs like a dream.
In the end I paid $350 and got an exchange recond carb and the car runs like a dream.
Rebuilding a carbi can never hurt.
seeing as urs is old as hasnt been done for a while, id say u will get a good benefit from doing it.
The kits is worth under $50 i know that much.
and being an L28 carbi, they are a farely basic carbi and should have it done before lunch time
good luck
seeing as urs is old as hasnt been done for a while, id say u will get a good benefit from doing it.
The kits is worth under $50 i know that much.
and being an L28 carbi, they are a farely basic carbi and should have it done before lunch time
good luck
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Haha, not quite before lunch time I'm afraid guys! Bought the kit for $39, came with washers, circlips, gaskets, a new throttle plunger and a new needle and seat for the fuel inlet to the float bowl. As I was pulling it apart, there were quite a few differences to the exploded diagram that came with the kit. I made a few notes as I went, but clearly not enough.
Had to leave it to do few things. Returned in the dark (under floods) to put it back together. Got very confused halfway through, ended up getting it back together with a spring and ball bearing left over and one screw short. Pulled it all apart again and managed to find a spot for the spring and ball bearing, left the missing screw out (may never have been there) and reassembled. Got the thin choke lever on eventually, but couldn't figure out where to put the long thin lever with funny bends.
Hurrying a bit now I put it back on the car and started the fuel pump. The float bowl window slowly started to fill up, and as it got up to the mark, I gave it a go. Started beautifully. Ran very rich I think, as I was able to push the choke all the way back in before it got warm. Ran quite well for a few minutes, although with a smidgen of hand throttle on. After that revs started to drop, and it stalled before I got to it.
Haven't been able to start it since. There was petrol everywhere - the (secondary?) chamber was full to 30-40mm from the top, yet the bowl was empty. Pulled it back off and opened the butterfly on the bottom of the chamber (the one actuated by the diaphram) to empty the fuel, but couldn't get any further.
I've left it for tonight and will see what I can do tomorrow.
Had to leave it to do few things. Returned in the dark (under floods) to put it back together. Got very confused halfway through, ended up getting it back together with a spring and ball bearing left over and one screw short. Pulled it all apart again and managed to find a spot for the spring and ball bearing, left the missing screw out (may never have been there) and reassembled. Got the thin choke lever on eventually, but couldn't figure out where to put the long thin lever with funny bends.
Hurrying a bit now I put it back on the car and started the fuel pump. The float bowl window slowly started to fill up, and as it got up to the mark, I gave it a go. Started beautifully. Ran very rich I think, as I was able to push the choke all the way back in before it got warm. Ran quite well for a few minutes, although with a smidgen of hand throttle on. After that revs started to drop, and it stalled before I got to it.
Haven't been able to start it since. There was petrol everywhere - the (secondary?) chamber was full to 30-40mm from the top, yet the bowl was empty. Pulled it back off and opened the butterfly on the bottom of the chamber (the one actuated by the diaphram) to empty the fuel, but couldn't get any further.
I've left it for tonight and will see what I can do tomorrow.
* Nothing is foolproof to a sufficiently talented fool *
Car is now running, and just manages to idle. It is rough as buggery though.
To stop it overfueling, it seems all I had to do was adjust the float level.
A couple of questions remain:
1. Where does the longer metal linkage go? Both ends are bent 90 degrees with one end having two tabs (which I assume means its designed to be held between the two) and the other has a tab near the 90 elbow, and a small hole for a split pin near the end.
2. Which way around do the jets go? There are two jets below the bowl, underneath hex head caps. Both are the same except one has a smaller hole through the centre of it. One goes in the secondary and one in the primary, but swapping them around doesn't seem to do much. There is a very similar thing happening under the air chute - two jets screwed down into the main carb body, next to the two barrels. Again same shape and thread, but one with a smaller centre hole. I put the smaller one next to the secondary, because my diagram indicated a "slow air escape" went there. But looking at it now, I'm not confident that's what it was refering to.
3. Thoughts on how I might getting it running nice? Is this a job for a tech or has a mixture bench and crap? Simply turning the idle adjustment screw doesn't seem to do a lot.
4. Does anyone have any decent diagrams/photos of this style carb? The exploded diagram that came with the kit was different at critical times.
I know, I know, I should have made note of the size of the jets, and locations of linkages/parts as I pulled it apart. I almost went looking for a camera, but didn't realise the importance of notes until I went to put it back together.
To stop it overfueling, it seems all I had to do was adjust the float level.
A couple of questions remain:
1. Where does the longer metal linkage go? Both ends are bent 90 degrees with one end having two tabs (which I assume means its designed to be held between the two) and the other has a tab near the 90 elbow, and a small hole for a split pin near the end.
2. Which way around do the jets go? There are two jets below the bowl, underneath hex head caps. Both are the same except one has a smaller hole through the centre of it. One goes in the secondary and one in the primary, but swapping them around doesn't seem to do much. There is a very similar thing happening under the air chute - two jets screwed down into the main carb body, next to the two barrels. Again same shape and thread, but one with a smaller centre hole. I put the smaller one next to the secondary, because my diagram indicated a "slow air escape" went there. But looking at it now, I'm not confident that's what it was refering to.
3. Thoughts on how I might getting it running nice? Is this a job for a tech or has a mixture bench and crap? Simply turning the idle adjustment screw doesn't seem to do a lot.
4. Does anyone have any decent diagrams/photos of this style carb? The exploded diagram that came with the kit was different at critical times.
I know, I know, I should have made note of the size of the jets, and locations of linkages/parts as I pulled it apart. I almost went looking for a camera, but didn't realise the importance of notes until I went to put it back together.
* Nothing is foolproof to a sufficiently talented fool *
Oh, and
5. My carby had one ventricle thing in the secondary barrel. The bit that screws into the main body with two long screws and has a section hangs out in the middle of the barrel. Between the two screws is another jet. I think I got that bit right - I put a spring in there at first, but then decided that's not where it goes.
Instead, on the primary barrel is a short brown cylinder that has a 2mm metal tube that exits the cylinder half way, extends out and then goes through a 180 degree arc to point into the barrel. In my notes I wrote that in this cylinder was held in by a hex nut, and contained a spring and a ball. Any ideas which goes on top? I think I've got the ball on the bottom, held by the spring. So as fuel/air comes up the jet, it'll have to push it's way past the ball and spring. Sound right? That left me with a thicker spring, which I kinda shoved somewhere... not sure that's right.
[Edit: got the location of the spring and ball wrong]
5. My carby had one ventricle thing in the secondary barrel. The bit that screws into the main body with two long screws and has a section hangs out in the middle of the barrel. Between the two screws is another jet. I think I got that bit right - I put a spring in there at first, but then decided that's not where it goes.
Instead, on the primary barrel is a short brown cylinder that has a 2mm metal tube that exits the cylinder half way, extends out and then goes through a 180 degree arc to point into the barrel. In my notes I wrote that in this cylinder was held in by a hex nut, and contained a spring and a ball. Any ideas which goes on top? I think I've got the ball on the bottom, held by the spring. So as fuel/air comes up the jet, it'll have to push it's way past the ball and spring. Sound right? That left me with a thicker spring, which I kinda shoved somewhere... not sure that's right.
[Edit: got the location of the spring and ball wrong]
* Nothing is foolproof to a sufficiently talented fool *
L28 carbi rebuilds
Fun mate, if u are confident u have it assembled correctly, then personally i would take it to the local mech to tune it up.
i always get my petrol tuned, i only tune my own LPG.
The assembly i cant help u with off the top of my head, i have a workshop manuel here from nissan big loose leaf booklet that the mechs at nissan used.
its got the L28 engine in it,
so i can grab the book tomorrow and post up wat info i can
screwy
Fun mate, if u are confident u have it assembled correctly, then personally i would take it to the local mech to tune it up.
i always get my petrol tuned, i only tune my own LPG.
The assembly i cant help u with off the top of my head, i have a workshop manuel here from nissan big loose leaf booklet that the mechs at nissan used.
its got the L28 engine in it,
so i can grab the book tomorrow and post up wat info i can
screwy
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That'd be sweet if you could get the diagrams! The exploded diagram I have is just too different at the critical times. I need to confirm that I have the part under the air horn right before I can put it down to tuning. Hopefully I can have a look at another carby at some stage too...
Latest news this morning is that I've swapped the jets over - at bottom of the fuel bowl and next to barrels I've put the smaller jets in the primary, bigger in the secondary. Also removed a spring that didn't appear to do anything, so I'm again left with a 10mm long, 3mm wide black spring that I don't know what to do with. Got that last longer linkage fitted too - it just opened the throttle a bit when the choke comes on.
After fitting, car needs choke to start, which is the way it was. Then runs, but rough:
1. At idle it wanders quite a bit.
2. Off idle, free revving is okay.
3. High revs starts to fuel up - black smoke and rich running.
4. Stamping the throttle open chokes it - backfires through the carby and drops revs dramatically before revving up.
So one step forward and two back!
Oh, and the idle mixture screw still appears to do bugger all (even completely closed!) but you can't see the fuel dribbling out of the main jet any more. I wonder where the fuel at idle is coming from then?
Now waiting on diagrams, or access to a (properly) built carby.
Latest news this morning is that I've swapped the jets over - at bottom of the fuel bowl and next to barrels I've put the smaller jets in the primary, bigger in the secondary. Also removed a spring that didn't appear to do anything, so I'm again left with a 10mm long, 3mm wide black spring that I don't know what to do with. Got that last longer linkage fitted too - it just opened the throttle a bit when the choke comes on.
After fitting, car needs choke to start, which is the way it was. Then runs, but rough:
1. At idle it wanders quite a bit.
2. Off idle, free revving is okay.
3. High revs starts to fuel up - black smoke and rich running.
4. Stamping the throttle open chokes it - backfires through the carby and drops revs dramatically before revving up.
So one step forward and two back!
Oh, and the idle mixture screw still appears to do bugger all (even completely closed!) but you can't see the fuel dribbling out of the main jet any more. I wonder where the fuel at idle is coming from then?
Now waiting on diagrams, or access to a (properly) built carby.
* Nothing is foolproof to a sufficiently talented fool *
OK heath, these are the 5 pages on the L28 carbi straight out of my official Nissan workshop manuel.....
If these dont help you much then ur gunna either have to check a built one or just take to a carbi specialist
But this is as good as i can do
cheers
If these dont help you much then ur gunna either have to check a built one or just take to a carbi specialist
But this is as good as i can do
cheers
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Ok they are indeed hard to see, my bad 
I have a copy of the originals on my computer here also and they are 100 percent spot on.
If anyone wants a copy of them feel free to drop me a PM or email and ill send them on no dramas, Heath email sent with the good ones.
good luck
I have a copy of the originals on my computer here also and they are 100 percent spot on.
If anyone wants a copy of them feel free to drop me a PM or email and ill send them on no dramas, Heath email sent with the good ones.
good luck
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Cheers Screwy, the emailed ones were spot on.
Good news folks, the old L28 is purring like a 23yo, grumpy and weak cat again! Well its running right, and a shite load better than before I pulled it apart last week.
So much nicer to drive:
Doesn't chug at low revs (that helps more that I realised, because it saves slipping the clutch a lot and having it screaming at high revs because it wont pull at low, means for quieter driving, slower crawling, and less jerk off the line).
Doesn't fart when you stamp on the throttle - pulls immediately and smoothly all the way up the rev range.
No missing and crap under power.
And finally - doesn't stall on gentle slopes! I'm going to have to adjust my driving technique to take advantage of this! Only tried a reasonable grass slope (probably less than 45 degrees) in 2wd, but having it idle all the way up until the rear tyres started to spin is such a nice feeling! I still have a bit of work to do in this area - going to find some tubes and run the top fuel pipes higher, cause that's the tip I've heard.
In the end, I used this arrangement of jets (everything else only has one way it'll fit) which was no more than a slightly educated guess based mostly on trial and error:
Main jets (the fuel jets under the caps below the fuel bowl): larger on secondary, smaller on primary.
Slow air bleed (short jets screwed down next to each barrel under the air horn): larger on primary, smaller on secondary. From memory the smaller was 60, the larger 240.
I also retuned the float bowl according to the workshop manual. It's pretty close to spec (eyeballing with a ruler) now, but once it's all back together, the fuel level with motor off, fuel pump on, is actually a bit below the mark on the window. When running it is maybe slightly less than 1/4 up the window.
Have to see how it actually goes on the road (rather than me cruising around the uni) and offroad before I declare it done (and look at getting it professionally tuned), but at this stage, I'm a happy chappy. Thanks for your help!
Good news folks, the old L28 is purring like a 23yo, grumpy and weak cat again! Well its running right, and a shite load better than before I pulled it apart last week.
So much nicer to drive:
Doesn't chug at low revs (that helps more that I realised, because it saves slipping the clutch a lot and having it screaming at high revs because it wont pull at low, means for quieter driving, slower crawling, and less jerk off the line).
Doesn't fart when you stamp on the throttle - pulls immediately and smoothly all the way up the rev range.
No missing and crap under power.
And finally - doesn't stall on gentle slopes! I'm going to have to adjust my driving technique to take advantage of this! Only tried a reasonable grass slope (probably less than 45 degrees) in 2wd, but having it idle all the way up until the rear tyres started to spin is such a nice feeling! I still have a bit of work to do in this area - going to find some tubes and run the top fuel pipes higher, cause that's the tip I've heard.
In the end, I used this arrangement of jets (everything else only has one way it'll fit) which was no more than a slightly educated guess based mostly on trial and error:
Main jets (the fuel jets under the caps below the fuel bowl): larger on secondary, smaller on primary.
Slow air bleed (short jets screwed down next to each barrel under the air horn): larger on primary, smaller on secondary. From memory the smaller was 60, the larger 240.
I also retuned the float bowl according to the workshop manual. It's pretty close to spec (eyeballing with a ruler) now, but once it's all back together, the fuel level with motor off, fuel pump on, is actually a bit below the mark on the window. When running it is maybe slightly less than 1/4 up the window.
Have to see how it actually goes on the road (rather than me cruising around the uni) and offroad before I declare it done (and look at getting it professionally tuned), but at this stage, I'm a happy chappy. Thanks for your help!
* Nothing is foolproof to a sufficiently talented fool *
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