So i was running my truck without a fuel reg and decided i might want to get one and set up my carb for it . i put it on set it at 3 and all hell is breaking loose. I am 3 out on the idle mix screws before hand and am currently around there now but anything out in the 2500 rpm range i get a back fire and engine stalls out, will restart and run great in 1st 2nd gear just under 2500 rpm. Im thinking a big set of idle jets to get mix screws back to around the 1 mark but how do i know when to get bigger main jets or the air correction jets, i research and all i getis to tune a weber do the idle speed and idle mix i can't find anywhere that goes on to the high side of things, i realized that a weber uses the low side 80% of the time i just want my carb right and possibly get better milage out of it. All help is welcome. Im about to just pull the regulator and go back to driving the truck it ran fine before hand.

 

Are you running the stock fuel pump? What kind/brand of FPR are you using? If you were running fine before I'd guess that it's not the jets, your flow is too cut down and you're starving out the carb. Try to get it to die by rapping it up while you wach your fuel press gauge. If the press drops too low under "high demand" you might need to go with a higher flow pump.
I just went through a nightmare with getting my press right on my dcoe's, so i feel your pain.

 

Stock pump and just a fprfrom az still at 3there out I need bigger idle jet just disney know how to set main jet or air correction jet.

 

Thought bout timing issue but don't see how it can with it good before regulator. Maybe I just need more flow bigger idle jet but still dunno how to set main or air correction

 

Didn't fully understand this. From what I could make out of this and next post, idle jet is fine. At 2500rpm main jet is more likely, if jets are the problem at all.
FPR from auto zone? Mr Gasget or specter? I haven't tried either of those but I have heard that they are complete crap and restrict fuel flow. I had a mr gastget elec fuel pump that went tits up after 3 weeks. People seem to like the holley FPR for the 32/36's and the 38's and I have been very happy with my redline/weber FPR.
I would temporally bypass the FPR and see if it fixes the problem. You said it ran fine before, right? Or was something wrong and that was why you put the fpr on? If you run fine without the fpr, that's your problem, not the jets.
You do have a gauge on the fuel line between the FPR and the carb, right? Just making sure you didn't just set the FPR to the "3" on the dial on top and call it good .

More info (preferably understandable) and we'll get that 82 acting right.

 

Sorry about typing was on a phone with auto correct and yelling kids. I went to fpr because I wanted to set it up to spec and not half butt. Gauge said it was 3lb at 5.5 setting and stock pump is 6.5 no reg so I went back to no reg it was specter and going to try to return it. Ibthought at 3 turns out or more idle jet is just a stream of gas and I would do better if I went bigger jet and turn screws in to get back in spec I guess just trying for better mpg and do things right I heard of 18-20town with a weber 38 im at 15 but have buggers tires but also regeared so I guess I want my cake and eat it too next to check is timing and maybe advance a little

 

Won't be perfect for you, but give a read through my sync-link thread
https://www.yotatech.com/forums/f114...talled-225236/
I was frustrated with the lack of jet setup info for our trucks, most everything I found for jetting recommendations were for BMW 2002's, so I gave it a shot fine tuning it. The other thing that may help you is blocking off your fuel return line. I haven't had a problem with it, but I do know people with Toys and other 4 cyl brands that once the regulator was installed, it would restrict volume to the carb and shove it back to the tank in the return line instead. Once the return line was blocked, it ran like a champ.

 

so now with no regulator and new plugs im going to try to lean out the machine a little plugs were tan but sooty around base ring and threads. and see what i get at idle and mid range. I will then do the wot jetting when AZ gets more plugs instock so i can cut the threads and see my porcellin. thanks for all the help. reg just won't keep up even with return line blocked off i guess to small orfice?! or just faulty since it read a couple pounds shy to begin with.

 

Ahhh, auto correct and screaming kids. Good times. Unfortunately the cheap FPR's just don't seem to work. They cut psi by cutting flow (or so I've heard). The holley is the cheapest that I've heard works most of the time. When I had a 32/36 I didn't use a fpr and the stock pump seemed fine. My DCOE's require me to be in the 1.5-2psi range and I have to run an elec pump so a good fpr was needed.
15 mpg sounds a little low. Trade in the specter for a holley fpr? Keep us posted and good luck!

 

ordered the holley fpr 804 will update when installed how jetting looks

 

Hey buddy, got your PM.

First off, the number one thing you can do to better match your Weber to your 22R is to ensure that you have no vacuum leaks. The stock adapter plates which come with the Redline 38 / 22R kit are complete crap.

Rating: Negative 5 stars out of five.

Who sells CAST IRON ADAPTER PLATES, with threaded rods as studs!? No matter the quality of gasket or RTV that you throw on there, they will never seal properly. Maybe for like two minutes, but as soon as the engine heats up, the plates expand, the studs move, and now you have an air leak. No thanks.

This is mostly important because as you tune your engine, it will be changing temperature, and as temperature changes, so does the severity of your vacuum leaks. You could be getting a huge leak when you first start, only to have it seal up once you're up to temperature. Or vice versa, you could have no leaks at startup, only to have a huge one at temp. This can be a huge nuisance and is definitely something to take into considerations.

I have seen threads on here where people have machined the plates down properly, then added real locking studs. This is fine if you're on a budget, but if you already splurged on the Weber 38, just spend the $250 to get the matching Offenhauser intake manifold: http://www.lceperformance.com/Downdr...-p/1032060.htm

Words can't describe the performance increase I have seen from bolting on this manifold. I now see why people love them so dearly.



NOW, that you don't have any nasty vacuum leaks...



The Weber carbs can be a beech to tune, but as long as you know the tricks, they will run better than stock.

The main thing you need to know is that you MUST stay in the range of needle adjustment that Weber specifies in the manual. Here is a quote from the Weber tuning website which is a MANDATORY read if you want it to run right. Don't just read it; understand it:

If the mixture screw is more than 1 1/2 turns out turns then the Idle jet is too lean (too small). When the mixture screw is ½ turn or less, then the Idle jet is too rich (too large). These assumptions are based on the fact that the speed screw setting is not opened more than 1/2 turn in.


(http://www.redlineweber.com/html/Tec...as_tunning.htm)


What they don't tell you, and you need to know, is that if your mixture screw is more than 1.5 turns out, fuel will actually be DRIPPING past your mixture screws, instead of being atomized through the ports. This leads to very inaccurate fuel metering, where it will be hard to tell if you're running too rich or too lean, since the mixture will be continuously changing.

Along with that, the speed screw setting is just as equally as sensitive. If the speed screw is adjusted more than 1.5 turns in, then the throttle plate / butterfly valve will move away from the transition ports in the venturi. This means that not only is there fuel coming from the idle port, but also the transition ports, so now you have even more fuel dumping into your carb.

When I first got my 38, I didn't really understand this, and I just kept backing out the screws since she was lean, until she ran somewhat OK, but I was still disappointed. Finally after READING and UNDERSTANDING the instructions, I realized I needed a jet kit. After enrichening the jets and re-tuning, she runs better than ever.

BUY A JET KIT: http://www.lceperformance.com/Weber-...-p/1035006.htm

These are way too expensive and should come standard with the carbs, as they are absolutely essential to proper operation. The jets that come with the carbs are ALWAYS too lean. This is mainly because they engineered the Weber carbs before they started messing with our fuel supply. Fuels nowadays run much more lean than they did 10 years ago.

Another thing I have noticed that has helped during this long quest of tuning my 38/22R is to advance the timing. Right now if I remember correctly, I'm around 5 degrees advanced. She still runs the same around 10, but as soon as I put her back to zero, she runs pretty rough. I have seen the same for other people with Webers; that they need to advance the timing a bit.

One last reminder about Webers: get a good fuel pressure regulator and a fuel pressure gauge, and stay under 3 psi! Any more pressure, the fuel will be forced past your float needle, which will overfill your bowl, which will mean you're running rich yet again.

In conclusion, note that Webers con be finicky if you don't know their flaws. However once you understand what every part does, and how they all affect each other, Webers can be the simplest, best performing and most reliable carburetors for the 22R.

No vacuum leaks, proper jets, proper tuning, proper timing, proper fuel pressure. All errors in these areas are due to operator error. For those who say that Webers suck... You're doing it to yourself.


I can't stress enough; READ AND UNDERSTAND the tuning guide:

http://www.redlineweber.com/html/Tec...as_tunning.htm


This can definitely be some confusing stuff if you're new to tinkering, so don't beat yourself up over it. Just take the time to understand, and you'll be set!

Good luck, and feel free to ask any questions!

 

PS, I have the Holley FPR which has been working fine for me. I also have a Holley fuel pressure gauge, which works fine, except this one time I got fuel on the gauge face, which like melted it and deemed the gauge unreadable. After sending an angry email to Holley, they sent me a brand new one. So, don't get fuel on your fuel pressure gauge........

Another thing I noticed is that you said it's backfiring with your mix screws 3 turns out. This is because the screws are not engineered to be turned out more than 1.5 turns, so fuel is leaking past the screws, and you're DUMPING fuel in the carb, so when it finally ignites, BAM, backfire.

Time for a jet kit!

http://www.lceperformance.com/Weber-...-p/1035006.htm

 

Thanks for the information I can't thank u enough I have been trying to get my head around why this and that was going on but u pretty much took care of it thanks. For goes in tonight jet kit in mail. Timing light in mail/broke old one and I will check vaccine as no money for offs right now I have three kids

 

so i have rejetted to 55 idles and 150 main 190 air f5 emulsion tubes, i runs a lot better 1 and 1/4 out on mix screws idle screw at 1/8-1/4 900 rpm and it raps out smooth and all but i get a little smoke when it accelerates hard? when i go down to a 145 main jet it diesels on shutdown? so up air or quit being picky? just seems a little rich? any suggestions also run 10 degree advance no hoses hooke and only run ported vac advance no mainfold advance

 

Glad to hear you got it running somewhat better.

If you're dieseling on shutdown, I would think that either your idle jet is too rich, or you still have a vacuum leak somewhere that is causing you to tune the carb more rich than it needs to be. Try spraying some starter fluid around your gaskets and listen for an increase in RPM. If you find a leak you should be able to put your idles back to 50's.

Did you try 50 idle jets? If so, how did it run?

What color smoke are you getting when you stomp on it?

 

the motor does not diesel at all with 150 mains and the 190 air jets even during throttle chop but with 145's during throttle chop it did i can always go back and try again i guess and jsut see what happens. i think tomorrow im gonna run it down the road and just see how it goes. The smoke i speak of is black rolls out the pipe just as u accelerate hold the pedal down and it goes away and runs great or back out of it and it goes away and runs great. The motor does not stumble or have flat spots at least as of in nuetral i will take it out on the road in the morning. Does anyone have a clue at normal round about jet size for a 22r adn weber 38 i can't find poop on these things as far as jet size. everyone say go by procedure and i do and only thing i got going wrong now is teh black puff of smoke. I ran 50 idle jets and they just never seemed to sound as good as the 55's . one more reason im trying to come up with a round about jet size.

 

lce sells their weber 38 kit with these jet sizes

Main Jet 154
Secondary Jet 154
Primary Idle 45
Secondary Idle 45
Air Correction (Primary) 185
Air Correction (Secondary) 185
Pump Jet 70


im close as i know a 45 idle has to be 3 out just to run mains a air are close to mine

 

Tired of going through plugs and not being satisfied. The guys around here say it sounds good quit reading into my plugs so much but I want most power for mileage too. So I bought innovate mtxl AT&T gauge so I can see my fuel curve so I can see the fuel transitions through out elms when I line this all out ill make a write up on the fuel curves I get with different jets then do it again when temp goes up next summer.

 

Wow, extremely interested in this idea. Mine has pretty much always run just slightly rich, even with the mixture screw set "correct" and any smaller jets leaning me out just a little. I'll especially be interested to see the curve to get an idea of the transition between idles and mains.