Jump to content

Help - G16A Suzuki Swift - Weber 32/36 - Little trouble between 1000-1500rpm

Recommended Posts

Hi, I am new to the forum, got here because of a carburetor swap I did on my car (wife´s car but I drive and she´s too lazy to drive so I am her driver anyways :P )


Of all the place, I had two choices, the MG club or the Datsun club, and I choose to come here. Mainly because the Datsun is a Japanese car (as far as Wikipedia tells me). I haven´t seen any of those in my country, but there is Nissan and Mazda, being Nissan like a son of Datsun (if I understood the story of Datsun correctly). And secondly, because you guys seem to know more about the weber adjustment than most folks on the web on other forums, I feel more at ease seeing more info and stuff here than any other place.


I bought my 32/36 from ebay, from the Redline e-store. And I have videos of how I installed it. Using the Toyota Tercel Kit, that (strangely) fits bolt-on to the manifold of my Suki.


(If any video is in spanish, skip to the next one, there are several takes on each one)


The thing is, I suffer from 3 things (make fun ye, I don´t speak or write english too well, I even searched the register question in google to look up the answer, being the answer inside the question... damm).


#1 The first thing is the off-idle stumble, I believed it was a timing issue, fixed a leak on the vacuum advance (I have ported and manifold vacuum, both of them broken), after that apparently that minimized a lot, it didn´t dissapeared but it minimized a lot. On the installation video you can see that if I blip the gas there an stumble, but waiting like 2 secons and blipping again there is no stumble.


#2 The second thing is pinging under 15000rpm, I believe it could be related to the gas quality (usin ron 91, as the manufacturer sticker says), but I could be also the timing, because (6 degrees initial timing btw) if I lock up the vacuum advance (by locking I mean not blocking the ported port, more like putting the adjustment screw on the vacuum canister all the way until it doesn´t move under acceleration), there is no ping or so little it doesn´t notice until you really try to hear it. But the car runs great and pulls hard good (if I gently push the gas to avoid problem #1)


#3 The third problem is when turning to the right, the off idle stumble is quite noticeable. But it doesn´t happen turning left, so far what I readed it maybe related to the level of the float so I believe I can address that.


My settings so far are:

Mixture screw: 1 + 1/2 turns exactly, or maybe 1 + 1/2 + 1/8 turns (being the 1/8 more like a little nugde).

Idle Screw: close to 1 turn, more like 7/8 or a turn, but the throttle plate are quite close, and there is no noticeable ported vacuum, even disconnecting the ported line and hooking it to a vacuum gauge shows little (needle varely moving from zero) vacuum.


My engine is totally stock, just rebuilt about 4 years ago to 0.30 pistons and bore, and the compression test shows 195 to 200 psi on all pistons (dry test - warm engine, not hot, just warm to almost cold). And pulls up to 21inHg of vacuum (something odd becase I haven´t seen anything above 17 to 18inHg on google).


So, no vacuum leaks, excellent vacuum, what am I missing? My finger and sight are tired of searching and no one locally really knows about webers, and I rather fix it myself than taking ti to someone else. Is like an old saying: "Would you lend you wife to someone to play with? Neither I would lend my car to some strange mechanic.


Any ideas gladly appreciated. Also, keywords, since I am quite limited on the words I know to use to search function correctly. My bad :(

  • Like 1
Link to comment
  • Replies 5
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

Trust me..... your writing and English is better than some other members with it for their first language.



First check and set/adjust the valve lash. I don't know the Swift engine at all, but if the valves are adjustable, set them properly. This will assure proper manifold vacuum and good carburetor adjustments and idle speed later. Make sure that there are no vacuum leaks around the base of the weber carb and bolts are tight.


Now get the timing sorted out. Disconnect the vacuum advance and set to the factory ignition timing advance. Connect the distributor vacuum advance up to the ported vacuum advance on the side of the carb. If idle speed increases turn it down to normal.


All the above needs to be set before making carburetor adjustments. Sorry, I'm not an expert on the weber so I'll leave that to someone else.




One thing....

Off idle stumble could be the accelerator pump on the carburetor. With engine off look down the carb and work the throttle. You should see a strong squirt of fuel. This extra gas helps the engine transition from slow idle speed to primary barrel use. Engines tend to run lean because the air isn't moving fast enough to suck in the correct amount of gas. All carbs are this way not just the weber.

Link to comment

Thanks for the pointer, got the valves adjusted in the afternoon, and now runs better but with this settings:

Idle Speed:800rpm

Speed screw: 2 turns

Mixture: 2 turns


After reading again, decided to use the basic settings just to test

Speed screw (after touching the lever right?):1+1/2 turns

Mixture: 1+1/4 turns


and I got that my idle rpms barely got above 200rpms, but with my current settings now I see vacuum on the advance port, so, from what I see, I need a smaller idle jet to close more the idle speed screw and a bigger jet primary jet to compensate the off idle stumble, right? 



P.S.: about the accelerator pump, if I don't see a squirt the first time but the next time I do, that should mean that there is something going on in that circuit right?

Edited by Swiftdoog
Link to comment

It should work the first time every time or it's no use.


The ported vacuum advance should be zero at idle when the throttle is closed. As the throttle opens it uncovers the port inside and manifold vacuum is applied to it and to the distributor which will advance above the initial setting. This is why I say to disconnect it when setting the timing as it will affect the setting. If there is vacuum present at idle, the throttle may be set too far open. This too far open may be necessary to compensate for some other poor adjustment in order to get the idle at a reasonable level. 

Link to comment

I actually disconnected and had my vacuum gauge connected to see what was happening,and indeed, with my current sets, I see that I have a problem with the jet size of the idle. Come to think of it, the Tercel kit is for the 1.5L, but my Suk is 1.6L, maybe that's the whole trouble, I am just too lean for the displacement and a bigger jet (which is odd since the guides says smaller) but I see the problem is around that

Link to comment

:thumbup:  :thumbup:  :thumbup: I finally got the idle problem solved. Remember my settings, ditch them. I am now 1+1/2 turn on the idle speed and 2 turn on the mixture. What I did was to follow what the manual said and some google.


The low speed circuit calibration said that my idle jet was too rich, that means that I just needed a hair of air. I found out that the secondary plate on the weber I have does have a screw to calibrate the opening of the plate at idle.




What I did was to actually screw in just less than 1/4 of a turn (more like 1/8 to 3/8) and that was it, That idle up to 700 rpm, and I could use the idle speed screw to go up and down as I need, in my case, close to 800 rpm (the manual calls for 950 but I rather go to 800 as the general rule). Also  :w00t: I could set up my air con vacuum actuator to open more the carb still being "BELOW"  :w00t:  :w00t:  the enrichment holes, that means no more vacuum advance signal at idle with the a/c on, also no more off idle stumble btw  :thumbup:.


The accelerator pump now does work, oddly  :confused:  and I see how squirts every time I push the gas. Now I just have to give a test drive, right now I am just chillin indoors because I felt light headed, I will be back with more info later.


Oh, my weber doesn´t have enrichment on the secondary, so it won´t draw gas from there, also I tested and no dieseling so far  :thumbup: . Amazing how a little hidden screw (in my case I had ease access to it) can do changes so much  :console:

Link to comment

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...

Important Information

By using this site, you agree to our Terms of Use.