Well, like I mentioned yesterday in another topic I would be doing a Weber carb rejetting guide. I did this to a 32/36 I have installed, but the process is the same for any DGV carbs. The type of choke doesn't matter, and neither does the type of motor you're putting it on. This should help all the people who buy them used and want to jet them properly for a toyota, as well as those who want a little extra power from one they had after making changes. I still suggest reading any of the books about tuning Weber carbs, but this is like a photo cliffnotes version.

Now, before you think that I am using some "magic" set of jets to make more power, take into consideration that every motor has different wear and tear, as well as mods. I have a highly ported intake, removed choke horns, bigger valves, powerful ignition, big exhaust, ect. So a motor closer to stock would use different jets. But I will list some results of what i got. The jetting kit is $60 from any carb place or online from Redline Weber.

Step 1: This is what you should already have under your hood.
Your setup may not look this simple, but it should. Block off the EGR at the back of the head, and remove all vacuum lines and charcoal can.


Step 2: Remove the air cleaner.
You will see the paper gasket underneath the base plate, if its still in good shape reuse it. You can also see the 6 screws holding the top of the carb on. The primary idle jet is inside of the idle cutoff solenoid, which is at the bottom of the photo off the passenger side of the carb. It has the wire going to it. The secondary idle jet is on the opposite side of the carb, but is just a brass screw. The idle jets sit inside those holders. Don't lose the o-ring seals on either of them. The kit does not include extras.

And yes, I realize i have taken all choke parts off of my carb as well as cutting off the square "choke horn". I did that to stop impeding the airflow into the throat of the carb. It is a little more cold blooded, but the extra airflow is well worth it.


Step 3: Remove the carb lid if you haven't already done so.
Don't worry, there are no small parts ready to jump out and disappear. I don't even remove the fuel line, i just flop the top out of the way. You will see down into the float bowl the two main jets. Above the float bowl are the two emulsion tubes and the air corrector jet. In almost every case, you won't need to mess with those. You are only doing the idle and main jets today. The brass thing on the bottom center of the float bowl is the inlet valve. Again, no need to mess with that today.


Step 4: TAKE NOTES!
I can't stress this one enough, take notes of the exact stock setup BEFORE you change anything. Write down the main idle, secondary idle, emulsion tubes (I wrote ac), main jets and how many turns out the mixture screw is running its highest rpm at. This photo was my stock jetting. If the mixture screw is out past 1.5-2 turns, you need to do the idle jets first. I did 1 step larger (65/55) and it got better, down to 2-3/4 turns but wouldn't idle below 2. So I stepped up another step (70/60) and that made it idle as low as 1.5, but runs best about 2.5 turns out. I will swap to a 75/65 combo later. I just didn't have jets that large in my kit. After you get it idling and driving nicely, change the mains. I should have started by just going 1 larger on the secondary main, (140/145) but since the idle proved it likes fuel, I went 2 steps (145/150). I left it there for today, and will rejet again after I put in my hybrid motor.


Step 5: The jetting kit
This is the kit Weber offers for 4 cylinder applications. It has sizes designed for most small motors. They make a 6 cylinder kit too, but those are larger yet. Do one jet at a time, and put your old ones into the kit where the new one came from. I also got spare o-rings for the idles and put them inside as well. Take care of this, it is the heart of this whole operation.


Step 6: the actual jets
Here is a closeup of the secondary side idle jet and holder. They aren't very large, and make sure you always get the o-ring out when you put an idle. Internal jets don't have them. I put fresh ones, and kept the old ones. As well as a new set of spares. They were $1 for all 4 when I got my jet kit.




Notes/tips
* Make sure that nothing falls down the carb. This can easily happen taking the upper body screws or air cleaner base screws out. If you do, you better hope you can take the carb off and fish them out.
* Make sure that all jets are clean of ANY dirt and debris. You see how small the holes are. It doesn't take much to clog a passage. And this is all after the fuel filter, so don't expect it to save you.
* If rebuilding an old carb, get a gasket set. It has a few of the important ones to change. The upper body is very important. It keeps fuel from sloshing out of the bowl on corners and accel/braking.
* Make sure the screw driver fits the jet slot. Sounds simple, but you dont want shavings clogging anything.
* Take your time, and only do one change at a time then drive it. That means, 1 idle step at a time. Then do the mains. In my head I knew I would need 2 steps on mains and 2 steps on idles, but I did it a little at a time. It reduces variables if you have any issues.


I hope this helps people. If i need to add photos I can. And I more than welcome you all to paste this onto other sites.

 

I'm a little surprised no one has commented on this yet, since carbs have been a hot thread topic the past couple weeks.

 

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*cough cough* lol





























































...jk good write up

 

Haha. See what happens when I try to help the noobs?! I get one guy turning his head and coughing while another guy says no comment. What are you two hiding from us?

 

i was picturing more of when someone tells a joke and people in the audience just cough and you hear crickets..but turn my head and cough works too. you should tell people when they are doing the reject that they should clean the emoulsion tubes as well. they just unscrew from the outside, spray some carb cleaner through them. Also do one at a time so they dont get em mixed up.

 

I was just being an @$$... but I'll definitely be keeping an eye here when I rebuild my Weber... though I believe it was jetted for a 22R which I would think is not much, if at all, different from a 20R.

 

Cool write up!

I'd like to add this tho: "Disconnect the battery if your doing this while the carb is in the vehicle!"

 

this is perrty cool... if i had a weber carb.. bahahhaha.. lolz... no but seriously dude... thanks for teh info...

 

I didn't disconnect my battery, because I kept starting it to check what I did. But it is a good rule of thumb. I just never do it for anything unless I'm wiring things in.

 

I know this thread is old news, but here we go.

I've been doing some jetting on my 32/36. The problem is I put in a [email protected] and .420" lift cam into my mostly stock 20R. In doing this the motor ran lean, so if I ran it with the choke about 1/3 applied it ran well until about 4k RPM. I'm a lightfoot at sea-level, so this was no big deal.

My lazy butt finally got a jet kit, so here's wazzup:

Stock jet sizes Primary/Secondary:

Idle @ 50/50
Main @ 130/135
Airs @ 170/120

I had off idle hesitation and it ran way too lean w/o some choke. I now am running:

Idle @ 60/55
Main @ 145/150
Airs @ 170/120

No more hesitation, better cold start, Idle screw about 2.5 turns out, smoother running through all RPM. The only problem is it feels like the engine still wants to try to pull harder. Will increasing the secondary air correcter to 180 help? I haven't run the combo long enough to make a mileage determination, but running it with the stock settings and the choke applied 1/3 I would get around 28MPG at cruise.

As it sits it runs WAY better without blowing any black smoke that I can see (side exit pipe). The motor has the factory manifolds and a 2 and 1/4" inch exhaust. Any input from some more experienced Weber pro's is appreciated. I think I'll put the secondary 180 air jet in just to see, but the primary circuit has improved drastically since making the above mods.

 

OK quick question. Idle jet is in the accelerator pump housing? Plus I only have one jet from what I can tell, the opposite side has a cast housing but it's flat. So I'm guessing only some of the carbs have 2 idle jets? I'm assuming a 32/36 would only have one since it's mechanical secondaries and only 1 idle mixture screw.

 

thats a great write up . thanks elliott

 

Jimmy, if you try the 180 and it works, perfect. I never mess with the air jets, because my weber guide says those are hard to nail perfect without an air/fuel gauge. I have the same carb jetted the same way, and its been on a bone stock 21r (2.0l little brother of the 20R) and it ran great. Put an out of the box weber onto that and lost alot of power and got a bit of an off idle stumble.

Some of the webers dont have a main/secondary idle jet. There is one on each side. I've noticed out of the box they are always a bit lean for a toyota if there is any exhaust work done. Once I wire in my new A/F gauge I will go back through this for everyone to compare my results and do any further adjusting.

 

I know this is an old thread but it's new to me. This is a huge help since I'm tweaking with my 32/36 on my 20r at the moment. My reason for doing so is at over 2.5 turns on the idle mix I notice a little hesitation on slow acceleration. I just bumped up my primary idle jet from 60 to 65. Now my idle mix is about 2.25 turns. It's much better, but still, an ever so slight hesitation on slow acceleration. I'm putting a 55 in the secondary idle tomorrow (currently has a 50). I'm pretty sure it has to be the jetting to cause the hesitation. My whole ignition system has had a refresh. I have a new fuel tank, pump, filter and soft lines. Also has a new exhaust system. The deq operator even said my truck was the cleanest running 70's vehicle he has ever tested. So if it isn't a jetting issue I'm not sure what else it could be. I also could be overly anal about the truck. Just gotta tweak it.

Thanks for the nice write-up!

 

I'm glad this is still helping people. The hesitation is the jetting. Mine went almost completely away after rejetting. It's probably a little rich on mine, but I don't care lol. Carbs are never perfect because the air temp and humidity are constantly changing. I have to tweak my idle setting about once a week to keep it optimum.

If you have any more issues ask away, ill try to help.

For your ignition is it all new and stock grade or aftermarket better grade? As in the plug wires, are yet parts store or high performance type? Is the coil a high voltage or stock replacement? I always upgrade my coil, wires and plugs on every vehicle.

 

The coil is a flamethrower 2, went with pertronix igniter 2, standard wires, reman. Distributor. I kept my spark plugs at the standard gap size. Would it help to upgrade my plug wires?

 

So finally I'm running a 70 primary idle, and 60 secondary idle. I haven't tested the mpg yet but I'm worried I'm wasting fuel now. If I went from 60/50 idle jets to 70/60 should I notice a big drop in mpg? Thanks!

 

I never noticed hardly any mileage drop. But I come from V8 hot rods, so anything over 10 is acceptable, and over 15 is great. I get around 20-22mpg last I checked.

You should try out some better than stock wires. I know buying the same part twice sucks, but when I swapped mine I noticed it went to high revs smoother and idled in cold weather better. The ones I run are only about 40 bucks from summit racing. Taylor spiral core 8.5mm or similar is what they're called.

The rest of the ignition sounds good though. I usually open my plug gaps an extra .005-.008" since there is a stronger spark behind it. Changing plug gaps goes effect the A/F ratio, but a small amount won't make any major changes for the worse.

 

Hey, could you maybe send me a link to the same wires you got? I'm having a hard time finding any sets in 8.5mm for the 20r app. Without fancy-pants distributors (I.e D.U.I dist, Mallory, etc)