Weber jets??All who live for their triples please read this

[steve260z]

Regarding the idle and not digging back through the threads, have you adjusted the butterflys to tame the idle? In other words, how open are they and how much exposure do the progression holes have to the motor vacuum?

[AZGhost623]

I cant remember, but I read somewhere that having a high number air corrector is indicative of some kind of other issue. Does anyone remember? Like the AC is masking another issue?

 

I daily drove the Z last week to get a better feel for it, and I damn near have it dialed in. Its changed a bit from what Rebello said to use when they dyno'd the engine (with his intake/exhaust setup). I dont know why my experience would need to have this changed when using my own components on the engine? 

 

But so far, with a F11, 160 main, and 210 AC its like a completely different car. I need to go up another size or two on the AC to help lean it out a little more for WOT. Going down in size on the main jet seems to really affect the punch it gives at WOT... smaller main jets makes the car completely gutless... Working with the AC side of it seems to really make a difference in the tuning of it.

Edited September 15, 2014 by AZGhost623

[turbeau]

current set up

180 air

F11 E tube

145 main

55 f8 idle

40DCOE

34 choke

 

I ordered a set of 50F9 idles and 150 mains. When I get them in and new AFR readings I will post the results.

 

The throttle plates are positioned so that they cover half of the first (closest to intake manifold) hole when viewed from the progression hole inspection area.

 

The car always had a really stable idle right at 1000rpm, then after the bung was welded on I cannot get it below 1500. If there is an incomplete weld at the bung could that cause an exhaust leak and effect the idle so drastically?

[steve260z]

Doubtful, I assume you don't hear a leak.. U would if you had one.

 

Did you take the carbs off to do the weld?

Edited September 20, 2014 by steve260z

[AZGhost623]

current set up

180 air

F11 E tube

145 main

55 f8 idle

40DCOE

34 choke

 

I ordered a set of 50F9 idles and 150 mains. When I get them in and new AFR readings I will post the results.

 

The throttle plates are positioned so that they cover half of the first (closest to intake manifold) hole when viewed from the progression hole inspection area.

 

The car always had a really stable idle right at 1000rpm, then after the bung was welded on I cannot get it below 1500. If there is an incomplete weld at the bung could that cause an exhaust leak and effect the idle so drastically?

 

So you loosened up each throttle arm, and set the throttle plate to the half moon state. Then you tightened up each arm, and reset your idle since now all plates are sync'd across the carb right?

[turbeau]

That is the weird thing, nothing was disassembled or taken off in any way to weld on the bung. I had the wiring for the gauge pre done, drove the car to the shop, he crawled under and sanded off some ceramic coating, drilled a hole, welded on the bung and then I plugged in the sensor. On start up the new idle was at 1500.

 

When I got home I did the routine of resetting the idle and it didn't change. I even detached the throttle arms, and backed out the idle speed screws all the way and the idle still read 1500 rpm. So to me that sounds like at least one of the carbs is stuck open on the inside. I will open up the suspect one to see if that is the case. It could also be the tach malfunctioning.

Or it could a malfunction at the tach. When I had the throttle arms off and speed screws out the exhaust sounded like the rpm's were at 7-900, eventhough the tach read 1500 still.

Here is the welded bung, and the super slick gauge install that kennymonster helped me do.

 

[steve260z]

Double check the bolts attaching the carbs to the manifold. more air is passing into the motor than before.

You would be able to tell if its running at 1,500 verses 1,000. Don't need a tach for that

[steve260z]

Franckly (LOL), F11 e-tubes are just about the worst in DCOE applications. They have bleed holes ABOVE the fuel level, which only serves to delay tip-in (read: flat spot). This is why you're running such a fat idle. Keith documented this on sidedraft central, the F7 e-tube is the one to go for if you're staying with Weber e-tubes. The one caveat is that it won't deliver great mileage because it's impedance is too low (small OD).

 

Most (if not all) of the Weber e-tubes were designed for downdraft applications and work really poorly in the sidedrafts. This is because the height of the auxiliary venturi passageway is lower on sidedrafts.

 

Transition has everything to do with the e-tube, this is what most don't realize. The e-tube/air jet combo controls WHEN the main circuit is able to kick in, and how strong that kick is. Most people just use a fat ass idle jet and/or accel pump shot to cover that issue up. This obviously causes problems elsewhere.

Again, I recommend people register with the Sidedraft Central Yahoo Group, if not just for the sake of taking a look in the Files section. In there you'll find Keith's White Paper on tuning these carbs. While some of the info can use some updating, the majority of it is very much true. It's a thoroughly scientific way of setting up the carbs, skipping the typical guess-and-check and he-said, she-said methods.

Well, I'm still tuning. Got the AFR gauge installed.

Running very rich at cruising, around 10.5 with 60f8 idles. Installed 55F11s. Brought up the cruising afr to 11.2ish but increased the "bog" greatly. I'm currently using F2 E-tubes. Whats your thoughts on the F2?

 

Thanks

Steve

[Leon]

Well, I'm still tuning. Got the AFR gauge installed.

Running very rich at cruising, around 10.5 with 60f8 idles. Installed 55F11s. Brought up the cruising afr to 11.2ish but increased the "bog" greatly. I'm currently using F2 E-tubes. Whats your thoughts on the F2?

 

Thanks

Steve

 

Refer to the quote you found. Your issues are caused by a poor choice of e-tube and exactly reflect what I described in the post you quoted.

 

The F2 is not a good choice for the DCOE. It's air bleed holes are too high up with none of them below the fuel level. This makes it an absolutely horrible tube when put in the DCOE.

 

The file of interest here is called F2_e-tube_in_3_wells, it illustrates that the F2 was designed for the Weber IDF and has no business sitting in a DCOE: https://groups.yahoo.com/neo/groups/sidedraft_central/search/files?query=f2

 

I found some good lines from Keith on the matter as well:

 

 

I modeled an F2 tube to illustrate that it would be a particularly poor choice for a DCOE because you'd be forced to use a rather small diameter choke ... There are almost no bubbles so very little bubble pumping contribution so everywhere within the dynamic range of the tube you'd get exactly the opposite results that you would want.

 

On the other hand the F2 is likely a better choice for the IDF since all the air holes would be submersed at tip-in. There are still a lot of holes which likely means it would lean out at high revs like Obert's graph predicts but Weber added an extra enrichment circuit so at WOT it'll compensate.

 

 

Wow! Just making an educated guess I suspect that all the F-tube development was done exclusively for the downdrafts. This would account for why I was able to significantly improve the Obert tubes for the sidefdrafts. At this point I'm dumbstruck.

Edited October 5, 2014 by Leon

[steve260z]

Leon, Thanks!!

So, what tube do you suggest? An f7? or another?

Steve

[AZGhost623]

F11's work for many on here, and some race with them, so I wouldnt necessarily call them the worst. Im currently running them and they work just fine.

 

ZRedBaron before his engine blew was running F2's (I think he was 3.1L as well) He had after market ignition setup (Electromotive), 40choke, 160 main, 210 air. F2's also have the smallest orifice opening for the main jet at 7.5mm so like someone stated its a lean jet.

 

I have F7's and tried them briefly. Unfortunately I decided to stop testing on them, and removed all my test notes I had on them. I was curious what the japanese tuners do on these engines, so I reached out to one of them via email (http://spark88.blog.fc2.com). He sticks to three types. F2, F9 and F11. His main goto choice on a 3.0L engine is F9. He starts with a 185 MJ and 230AC and adjusts from there. HIs blog is incredible, might be worth to check it out, but he is super secretive with specifics. Use google chrome so it auto translates for you.

 

I have a slew of parts to try out still and see what works best. But I think I need a dyno to really tell me. Right now my car is up in the air as Im swapping out the diff with a higher gear, but as soon as thats done Im going to be testing some more now that it has cooled off here in Phoenix. I have the following etubes F2,F3,F7,F9,F11,F16 with mainjets from 140-185, and air correctors from 165 to 230. Ill be able to test pretty much any kind of setup on my 3.0L.

Edited October 5, 2014 by AZGhost623

[Leon]

Leon, Thanks!!

So, what tube do you suggest? An f7? or another?

Steve

 

The F7 seems to be the best solution as far as Weber e-tubes go. It'll be a bit fat at cruise because of its smaller impedance but low-end and midrange throttle response should be way better than any other tube. Just remember to set your float levels to 25mm using the top-down method (unscrew a jet stack and measure from the top down to the fuel - should be 25mm).

 

F11's work for many on here, and some race with them, so I wouldnt necessarily call them the worst. Im currently running them and they work just fine.

 

ZRedBaron before his engine blew was running F2's (I think he was 3.1L as well) He had after market ignition setup (Electromotive), 40choke, 160 main, 210 air. F2's also have the smallest orifice opening for the main jet at 7.5mm so like someone stated its a lean jet.

 

I have F7's and tried them briefly. Unfortunately I decided to stop testing on them, and removed all my test notes I had on them. I was curious what the japanese tuners do on these engines, so I reached out to one of them via email (http://spark88.blog.fc2.com). He sticks to three types. F2, F9 and F11. His main goto choice on a 3.0L engine is F9. He starts with a 185 MJ and 230AC and adjusts from there. HIs blog is incredible, might be worth to check it out, but he is super secretive with specifics. Use google chrome so it auto translates for you.

 

I have a slew of parts to try out still and see what works best. But I think I need a dyno to really tell me. Right now my car is up in the air as Im swapping out the diff with a higher gear, but as soon as thats done Im going to be testing some more now that it has cooled off here in Phoenix. I have the following etubes F2,F3,F7,F9,F11,F16 with mainjets from 140-185, and air correctors from 165 to 230. Ill be able to test pretty much any kind of setup on my 3.0L.

 

I never said F11 tubes are "the worst", nor any tube for that matter. Some are just better than others, and while there definitely is a "worst" one, I haven't bothered to find it.

 

Also, it's important to note that the e-tube is not the only part of the carb's metering controls. We're talking about just one piece of the puzzle here, but in order to have a properly tuned engine one has to take a more complete approach. What are your float levels? What ignition system are you using? Are your valves adjusted properly? And it goes on.

 

Keep in mind that using racers for comparison to primarily street-driven cars is invalid. They don't really care about the e-tube very much. If the motor spends most of its time in the main circuit, the e-tube isn't doing anything in terms of tip-in. All it has the ability to do at that point is control how much the mixture leans out at high rpm. I don't think most people really understand this concept and just wing it on e-tube choice usually purely based on he-said, she-said type of information. Why do you think F11s "work" for so many people here? I bet it's because it's the tube that came with the carb. My carbs came with them too. They sucked.

 

It depends on your definition of "work". If "work" means you have to pick a soggy idle jet and live with a flat spot, well then have at it!

 

FWIW, I've never heard of using main jet orifice opening in the e-tube as a tuning tool. Sounds really silly to me. The main jet performs the metering of the main circuit. A typical main jet will have 25 times less cross-sectional area than that 7.5mm orifice you mention!

[steve260z]

I ordered up some F7s and shall report back.

thanks

Steve

Edited October 6, 2014 by steve260z

[Leon]

I ordered up some F7s and shall report back.

thanks

Steve

 

Just remember that off-idle stumbles are different than tip-in stumbles. You can test for an off-idle stumble by very slowly and steadily bringing the revs up in neutral from idle to about 2500RPM. If it stumbles doing so, you either have the incorrect idle jet and/or you need to drill a new progression hole. With the F7, you should be able to run leaner idle jets and smaller air jets.

Edited October 6, 2014 by Leon

[AZGhost623]

Leon -

 

So I tried out some F7's that you recommended to Steve.... did a long drive with them on surface streets, and freeway. Basically I just took my jets I had on my F11's and moved them over to the F7's since they seemed to work on the round the block test (160 MJ and 220AC). Its a little rich at WOT 11ish, but other than that, couldnt tell any difference over the F11's. Any further testing for me needs to be on a dyno at this point.

[Leon]

You guys need to understand, we're working with a system where one change affects many other things. There are plenty of guys out there running DCOEs that are "satisfied" with the way their car runs. The beauty is in the tuning, not simply swapping parts. If setting up carbs was that easy, there would be not debate!

 

The F7 is a much better suited tube for DCOEs because it allows you to run leaner idle jets and accel pumps. If you have a tip-in stumble (different than off-idle stumble), a proper e-tube combined with correct jetting will solve that as well. If nothing else, throttle response will be crisper and you'll get better gas mileage. There is no magic bullet here, you have to work with the system, not individual parts.

[steve260z]

Leon,

 

Got the F7s. Now I broke the cardinal rule of changing only one thing at a time but had no choice. While I was waiting for the F7s to arrive I was inspecting the timing and other stuff and realized that my high tension wire (taylor) was not even seated in the distributor cap. The circuit was having to make a jump to the cap and while repairing the high tension cable the connector broke. So, I'm now running what I have to think is a better ignition system. So, factor that into the results.

 

Car runs much better with the F7s/new cable. My dead spot/stumble is all but gone. One hickup occurs at WOT at 3K. Then smooth from that point one. /going to test some idle jets I have laying around.

SS

[Leon]

Leon,

 

Got the F7s. Now I broke the cardinal rule of changing only one thing at a time but had no choice. While I was waiting for the F7s to arrive I was inspecting the timing and other stuff and realized that my high tension wire (taylor) was not even seated in the distributor cap. The circuit was having to make a jump to the cap and while repairing the high tension cable the connector broke. So, I'm now running what I have to think is a better ignition system. So, factor that into the results.

 

Car runs much better with the F7s/new cable. My dead spot/stumble is all but gone. One hickup occurs at WOT at 3K. Then smooth from that point one. /going to test some idle jets I have laying around.

SS

 

Did you try your old jetting with the repaired ignition system? That would be telling whether the F7s helped or not.

 

In any case, does that hiccup occur if you went WOT at 2k and as you pass 3k, or does it only occur if you go from cruising to WOT while at 3k RPM? This is an important distinction.

[steve260z]

Leon,

going to swap out the ETubes next but I've tried two different idle jets. 55F11 and 60F8. The 60s run great but too rich. AFR is in the 10s when cruising but the car is very responsive. Now the 55s run like crap. AFR tends to be too lean but jumps all around and runs generally crappy. What would be a suggestion on the idle jet? One thats slightly leaner than the 60...

Thanks

[Leon]

Leon,

going to swap out the ETubes next but I've tried two different idle jets. 55F11 and 60F8. The 60s run great but too rich. AFR is in the 10s when cruising but the car is very responsive. Now the 55s run like crap. AFR tends to be too lean but jumps all around and runs generally crappy. What would be a suggestion on the idle jet? One thats slightly leaner than the 60...

Thanks

 

Frankly, I don't have enough experience with Weber idle jets to make a good recommendation. Now, I can stare at the various jets and probably be able to push you in the right direction but I just don't have that kind of time right now unfortunately. I've been using Keith's hypojets. They're much simpler and more effective than the Weber stuff.

 

Let's try this, take a look at your 55F11. It should have a fuel orifice and air bleed holes. Generally, the more air bleed area you have, the leaner your idle gets and the richer your cruise mixture gets. The right fuel orifice gets you in the ballpark. I would start with seeing if you can find either a 55 jet that has less/smaller air holes than than F11 or a 60 series jet that has more/larger holes than the F8.

 

This chart may come in handy: http://www.classiczcars.com/forums/attachments/carburetors-s30/55753d1345764945-weber-dcoe-tuning-swap-shop-sticky-dcoe-idle-jets.jpg