Need help tuning a sidedraft on GSL-SE
10-01-04, 12:48 AM
#1
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Need help tuning a sidedraft on GSL-SE
I just installed a 45 Weber sidedraft on my stock six port 13B. I am having problems trying to tune my car. It idles fine but as soon as I try to hold a steady R.P.M. over 15 hundred the car misses uncontrollably. It almost seems to be a problem with the ignition but I'm not too sure because the car ran ok with the stock fuel injection.
Can someone give me advice on what might be the problem (jet sizes, timing setting,...). Thanks in advance.
Can someone give me advice on what might be the problem (jet sizes, timing setting,...). Thanks in advance.
10-12-04, 07:23 PM
#2
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im having a similar problem with my mikuni sidedraft which is a very simular setup... i tried adjusting the accellorator pump located down undernieth, if you look at the unit long enough and try to figure out how it works, then you should be able to figure out how the adjustments are made. this helped mine quite a bit, but i wanted to look into getting it professionally tuned, since i dont have the resources or background knowledge, aka air fuel gauge, correct tools etc etc. hopefully someone out there knows thier stuff and can help us both out... 
10-23-04, 03:01 AM
#3
Hm. What all did you do for the swap? I'm concerned about several things.
1) webers do not take all that much fuel pressure to run. THe stock GSL-SE pump does something incredible compared to what the weber will need (It needs anywhere from 3 to 7 depending on application, and gsl-se goes upwards of 40 psi i believe). The addition of a fuel pressure regulator with return line connected may be necessary for your application. I'm not sure on this one.
2) Is it blowing smoke when it is cutting out? If so what color?
As far as timing goes, play this one by ear. Make adjustments, test drive. adjust, drive, etc. Timing numbers won't tell you diddly. Every setup is different, find what works for you.
As far as jetting goes, it really helps to have an air/fuel guage at least, preferably a wideband. BUT, beings you probably don't have those, here's something you can try if you want to:
Start at a stand still. Accelerate hard all the way to redline through 3rd gear. When you get redline, turn off the car, coast/brake down to a stop. Pull the leading plugs and see what color they are. Dark/wet means rich, light/tan means lean.
From here you can start to draw conclusions.
Here are some basic tuning tips:
*If it falls flat on its face under wide open throttle, screw in your "idle mixture adjust" screws. Small incrimental turns is all you need, i'm talking 1/2 turn at a time, tops. Make SURE you adjust both an equal ammount.
*If it is leaning out under low/mid RPM range, you need LARGER main fuel jets (the tips of the jet assembly)
*If it is leaning out up top (you checked this when pulling the plugs), you need SMALLER air bleeds (the flat-round bits that are underneath the screw end on the 'top' of the jet assembly)
*As said before, timing is 'play by ear'. Every change you make will require a re-adjust of the timing. Too retard and you won't get any power. Too advance and you risk detonation (more of a concern on turbo'd vehicles). Try to find out whats a happy medium, because advance means more power but slightly more risky. I've got mine set at about 2/3rds advance. (Advance is turning the distributor clockwise, so that the screw is closer to the right. retard is counter-clock, screw closer to the left or front of car).
Hope that helps you out some. PM me if you require any more help!
1) webers do not take all that much fuel pressure to run. THe stock GSL-SE pump does something incredible compared to what the weber will need (It needs anywhere from 3 to 7 depending on application, and gsl-se goes upwards of 40 psi i believe). The addition of a fuel pressure regulator with return line connected may be necessary for your application. I'm not sure on this one.
2) Is it blowing smoke when it is cutting out? If so what color?
As far as timing goes, play this one by ear. Make adjustments, test drive. adjust, drive, etc. Timing numbers won't tell you diddly. Every setup is different, find what works for you.
As far as jetting goes, it really helps to have an air/fuel guage at least, preferably a wideband. BUT, beings you probably don't have those, here's something you can try if you want to:
Start at a stand still. Accelerate hard all the way to redline through 3rd gear. When you get redline, turn off the car, coast/brake down to a stop. Pull the leading plugs and see what color they are. Dark/wet means rich, light/tan means lean.
From here you can start to draw conclusions.
Here are some basic tuning tips:
*If it falls flat on its face under wide open throttle, screw in your "idle mixture adjust" screws. Small incrimental turns is all you need, i'm talking 1/2 turn at a time, tops. Make SURE you adjust both an equal ammount.
*If it is leaning out under low/mid RPM range, you need LARGER main fuel jets (the tips of the jet assembly)
*If it is leaning out up top (you checked this when pulling the plugs), you need SMALLER air bleeds (the flat-round bits that are underneath the screw end on the 'top' of the jet assembly)
*As said before, timing is 'play by ear'. Every change you make will require a re-adjust of the timing. Too retard and you won't get any power. Too advance and you risk detonation (more of a concern on turbo'd vehicles). Try to find out whats a happy medium, because advance means more power but slightly more risky. I've got mine set at about 2/3rds advance. (Advance is turning the distributor clockwise, so that the screw is closer to the right. retard is counter-clock, screw closer to the left or front of car).
Hope that helps you out some. PM me if you require any more help!
10-23-04, 07:54 AM
#4
yes, start by listing everything else that you installed with the carburetor ...
also, did you buy the carbie new or used? i'm asking simply to know if you can reference parts (jetting, venturis, accelerator pump, etc.) without pulling it apart. if new, just list what the specs are. if used, then start by listing the jets you've got on there now because maybe the carbie was used on an engine with a completely different setup than yours.
paint as clear a picture as you can.
also, did you buy the carbie new or used? i'm asking simply to know if you can reference parts (jetting, venturis, accelerator pump, etc.) without pulling it apart. if new, just list what the specs are. if used, then start by listing the jets you've got on there now because maybe the carbie was used on an engine with a completely different setup than yours.
paint as clear a picture as you can.
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