I ran the mixture screw all the way in and it didn't really affect the engine, was about 1 turn out. Still running normal. From what I understand that could mean I need to go down a jet size. Is this right?

 

Dont know Webers but for stock carbs IMO if theres no vacuum leaks your needing a carb cleaning, blocked idle passage i'd guess. Dont know what others think. Might try removing adjusting screw and spraying carb cleaner in there then blow it out, might or might not help? What you say sounds right, let us know...

 

This is a brand new carb with less than 500 miles on it. Shouldn't need to be cleaned.

 

Where are the experts? I was thinking if you set the throttle screw way down till it runs with a stumble if you can, then try to adjust the idle screw and see if theres an effect? Might clean inside of tail pipe and keep an eye on it to see if its running rich like you think?

 

I'm no expert, but I do know that the how to tune a Weber guide goes through this in detail, so there shouldn't be any guess work, assuming you don't have vacuum leaks. There is also a thread in this section on the finer points of tuning a Weber which aren't spelled out quite so well in Webers instructions. A simple search ought to bring that thread up.

 

If your idle speed screw is turned in more than a certain amount (0.5 on my 38 I think it is different for 32/36) then it lets fuel in from another orifice in the engine, which makes the idle mixture circuit irrelevant or not work properly, it may be your problem but I'm no expert either, if you find the thread in this section about weber tuning you will probably be able to figure it all out. If you have a 32/36 (you didn't state) I'm pretty sure you don't need to go down a jet size on a stock 22r.

 

I have never read about what your referring to the idle circuit not working due to screw position. I have read the weber tunning guide multiple times and I can run the mixture screw in all the way and the engine will still run just fine and the exhaust smells rich. From I understand if the screw is in all the way on a properly jetted carb then the engine should run ruff because its so lean.

And yes I have a 32/36 with a trandapt 1 piece adapter. I have checked for vacuum leaks around the carb.

 

https://www.yotatech.com/forums/f114...tuning-261129/

Post #7

 

If it runs with the mix screw all the way in, it's probably running off of the idle speed adjusting screw being set for too high of an idle speed. I'm not saying this right, but basically the idle speed screw setting can mask the effects of the mixture screw setting. That's the reason for the base line settings for both.

 

Hmm I guess I don't quite get the tunning thing then. I guess I will put the mix screw to 1 1/2 out and reset idle accordingly. So how do I know which way to turn the screw to adjust it or should the default be ok?

 

Seems like if you close the idle speed screw till the butterfly is closed or near closed (if it will close all the way?) and the motor should stumble i'd think. If you can get it to idle bad then adjust the idle mixture and if no result positive result, open the frig and grab a brew?

 

Ok well I played again with this today. I set the mixture screw to 2 turns out and speed screw to 1 1/2 in per instructions from weber. Well the truck wouldn't stay running lol. I had to raise the speed screw to about 2 1/2 in to get it to idle. All weber literature says no more than 2 in on the screw (1 1/2 is best). If its more than 2 it said to go down a size on the primary idle jet. So i went from a 50 to 45 on the primary idle and from a 55 to 50 on the secondary. They had a one size difference so i figured maybe it was best to keep it that way.

So now I have the speed at 1 1/2 in with an ~800 rpm idle and the mix is at 1 turn out. Seems to run better and is within tolerance according to weber. I also found a not that said you should have no vacuum at the advance port on the carb. I remember before I had about 2" of vacuum and now I have zero so it think I did it right.


I'm also gonna order a the fuel pressure gauge from LCE. I don't really trust the Mr Gasket one I have, its gonna some kinda residue on the inside of the lens so something may have happened to it.

 

Good job on the tuning, are you happy the way it runs?

 

So far I am. I also ordered the certain model NGK spark plugs that LCE recommends and they should be in tomorrow. See how that goes with those.

I kinda want to order the innovate air fuel ratio gauge. It comes with an O2 sensor and thread piece to weld in. It also has this computer thing (LC2) that constantly tracks your A/F and records it and you can transfer the data onto a laptop and there is a tuning software that comes with the gauge you use to try and tune the carb.

It comes in green and is a 52mm gauge so it would fit in the SR5 pod plus the green would match. It's $160 for all of it. I would love to see how much you could really dial a carb in with it.

 

Yes I want to get that too! much better, easier and faster than reading plugs and all, you can really dial in the carb to perfection with that if you understand everything.

 

I think it would be really fun, glad someone else has thought about it. I'm good with computer stuff. I program HVAC automation systems for Trane so I should be able to handle the tuning software. It may just be me but it bothers me not knowing how well my engine is running lol. I want to see some data on it, not just the color of spark plugs lol

 

I know what you mean about the engine not running at optimum, I also like doing the best with what I have i.e. spark plug gap, timing advance, carb tune, etc. What I mean by understanding is more about the carb and what each circuit does at what load and rpm, and how to interpret graph vs engine performance but it isn't all that hard, many carbed v8 of all types have been tuned with wideband in the last 10 years and more with the best results. A dyno is also a good tuning tool with dataloging.

 

I wish there was a way to data log the rpms too in junction with the air fuel ratio.

 

Well I found a small vacuum leak. Gotta try and fix it. Pretty sure it's the vacuum port on the manifold again.