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datfreak

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

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Its changed... 

 

38 choke 160 main 230 air 60F9 F7 Tube 00 Pump 45 Pump Jet

 

Initial Timing is 14, all in at 34.

 

Anything below 60F9 doesnt work for me with the lean spot.

 

Was supposed to get it dyno tuned a few weeks ago, but got horrible food poisoning and wasnt able to make it out there. Im set to redo my dyno tune on the 12/22 when I have vacation for 2 weeks. I have pretty much every combination you can do for jets, tubes and such, so we will see where I end up.

Edited by AZGhost623

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Spent all day at the Dyno shop on 12/22/14, but ran out of parts to keep testing. They were very thorough, except when it came to testing emulsion tubes. They immediately took out my F7 and replaced it with an F11. Must be the goto tube or something. They plugged right into my O2 sensor on my exhaust for AFR readings on their computer. They rebalanced my carbs, and set ignition timing and my rev limiter as well.

 

So this is where we ended up. Which is not too great but works for now (I did yield 214hp). Mid range is definately a lot more punchy now. Instant pulls from any gear when rolling. Freeway driving Im at 3000 rpm due to my gearing so Im at the start of the sweet spot. Stop light starts, not soo good.  You want your AFR (right side on 2nd picture) to be as flat as possible around 13. You can see I now start off  really lean (which I noticed driving home in stop/go traffic on the freeway). Midrange is a tad rich now, with high end being about where it needs to be. The shop recommended to go with a bigger choke and bigger main jet and see what happens, but as Leon pointed out, thats just going to cause my low end rpm range to be even worse. So I may try and switch out to F7's again since they were a bit rich and see what shows up. Maybe a bigger pump jet to bring that initial in?

 

Unfortunately I did NOT get a dyno sheet that showed what my car produced when they first tested it. All I got was final results.

 

So to sum up...

 

I need to gain 1 to 1.5 points in my mid range, and bring in my low end as well. Thoughts? Suggestions? 

it also would be helpful for me to find a cheap datalogger for this AEM UEGO AFR setup I have.

 

 

38 Choke 145 Main 165 AC 65F9 F11 0 bleeds 45 pump jet

 

 

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Edited by AZGhost623

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had been on the dyno last week. as for the 152 chokes went from 40 to 36 and from mains 155 down to 140. ac had been 200 previously and now is

195. first street run had been with 40 pumps and 0.4 bleeds and 60f8 idle. had not been workable. the typical bog once you go wot. emulsion is f16.

improved quite a bit once pump had been 50.

 

was 237 horses and 227 lb ft with the above jetting.

 

currently waiting for new jets. will try next the following :

 

choke 36

mains 150

ac 200

idle 60f9

bleeds 0

emulsion f15 or f2

pump 55 or upwards

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good stuff from everybody on here.

 

Today I went from 34 chokes, 150 main, 180 AC, 50F9 idles, F11 ET

to

30 choke, 120 m, 180 AC, 50F9, F11 ET

 

With the initial set up the car idled at 10.5, cruise between 12-13 and WOT about 13 afr. Tip in from any rev range would spike way lean to 19+ afrs causing stumble, then linear power to 6k rpm (the highest my wimpiness would go)

 

I switched to the 30 choke after reading through datsungarage site and I liked the way he described the new drive-ability of the 30s. Now it idles at 11.25, cruise 13, WOT 13. There is still a small stumble, about .5 sec when tipping in, then full power. It takes off cleanly and stays linear straight through the transition.

 

I thought the car would feel slower but it felt the same, just easier to drive. The afr's were more stable and the car was more predictable to drive.

 

Stock L28

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I did see a difference at the time where my engine was pinging. Timing change to avoid ping definitely made a difference.

 

Now, I've got a distributorless ignition I can change timing on the fly. I've got some lean AFR conditions at high rpm so I've done some tests. I have not seen any difference in AFR reading with engine running in proper conditions (no ping)

 

So to answer your question:

- Engine running properly, Timing does not interfere much with AFR

- Engine running poorly, timing could have significative impact.

Edited by Lazeum

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just wondering about the lean condition they have between 2-4K they say it is the accel . pump. as for some graphs i have seen

there is everytime the same lean condition in that rev range on the dyno graphs. why is that ? it does not seem that the cause are the accel pumps.

 

also why are most of the holes on the emulsion tubes everytime in the middle section ?

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Sorry to say, those guys don't understand how to tune sidedrafts. 
 

just wondering about the lean condition they have between 2-4K they say it is the accel . pump. as for some graphs i have seen

there is everytime the same lean condition in that rev range on the dyno graphs. why is that ? it does not seem that the cause are the accel pumps.

 

also why are most of the holes on the emulsion tubes everytime in the middle section ?

 

Good observations. The lean spot could be due to the e-tube and not the pumps. Different dynos will have different AFR profiles, especially at the start of the run, depending on the type of dyno and its settings. A load-bearing dyno such as a Dynapack has the ability to hold the car at WOT for a set amount of time before beginning the pull. This gets rid of transients (accel pump shot) and makes the runs much more consistent back-to-back. Ideally, once the main circuit is tuned in this manner, the pumps can then be tuned by performing transient tests.

Weber designed all their emulsion tubes for downdrafts. None of them are optimized for the DCOE.

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Still tuning (like what's new...) but I've totally rid the car of the dead spot. Under acceleration the motor would bog down around 2,500 rpms. Using Keith Franck's advice has been awesome. I set the float levels at 25mm from the top of the carb and didn't worry about where the brass floats were in relation to the gasket. On mine the spec level was 8.5mm. Ended up more like 6.5mm. The transition is absolutely smooth. 

Edited by steve260z

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Anybody got updates?

We've gone a full year not touching the best thread here. I'm out of content since I've had the front suspension apart redoing the springs, struts, ball joints....In addition to oil leaks, misfires, dual mass flywheel, clutch, radiator, expansion tank, coolant routing hose, window tint crap, door lock actuator, HVAC blower motor, valve cover gasket, and thermostats issue with the 2 BMWs in the driveway.

Anybody want to buy a E90 335i?

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Weber designed all their emulsion tubes for downdrafts. None of them are optimized for the DCOE.

 

Nice! Well, not nice.... but nice to know! I was never very impressed with changing E tubes. Thought I was missing something. Probably still am.

 

 

Anybody got updates?

We've gone a full year not touching the best thread here.

Hard to believe, I remember we used to get 20 emails a week on this thread.

 

I have two updates, well, maybe they're sort of the same update:

  • I will be engine-dynoing my new, rebuilt, new-rebuilt race motor (third time's a charm!) this spring / summer. I will be comparing 40 DCOEs (36mm venturis) to 45 DCOEs (36mm venturis) on the same motor, same day (two Cannon manifolds port-matched respectively). I don't know of such a comparison on the internet or in a book for any application. The comparison isn't fair to the 40 DCOEs, as my head outflows what the carbs can deliver. This is the whole point of the unfair experiment... to compare the dyno plots of a restricted intake (past the Weber flowcharts) to a more appropriate intake (within the charts). Appropriate being relative, of course, because 45 DCOEs are still a top-end compromise for a full race motor, and this is a deliberate compromise to maintain low-RPM torque and throttle response (autocross).
  • This experiment is partly a result of painting myself into a corner in a discussion that came up on my engine thread, and partly out of my own curiosity and enjoyment of our mutual hobby. Weber debate begins here, which ultimately trails off with me citing a Weber chart and then saying I'll let the dyno settle the debate once and for all. My theory is that the draw of the pistons at a given RPM creates a given vacuum signal regardless of intake, drawing metered amounts of fuel set by the carburetor / jet combo. If under-carbureted, inadequate air matches fuel metered for adequate air, producing a rich condition. (The carburetor "feels" more airflow than is actually present.) This cannot be patched at high RPMs with air correctors, because what the engine needs is a more open intake, period. The thread has been pretty silent, not sure if I was too aggressive with my argument? Regardless, should be a fun experiment. We all expect HP and torque to rise... but what about the A/F graphs? What will those look like?

And no, I'm not trying to send the debate to this thread. I've already typed too much on the subject as it is! Just completing the circle and replying to Steve. He's right, it's been a long time coming.

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I'm now working on rebuilding a set of DCOE 40s I bought off a member on here. They were pretty nasty inside and the shop I dropped them off at for cleaning couldn't get the choke/starter circuit/enrichment cam brass tubes out in one piece. They're the little tubes that have a skinny portion in the middle. They don't do anything but activate the starter circuit as far as I can tell. Has anybody simply plugged these? Or maybe someone has a stash of the less common parts laying around they could sell? 

Any help rebuilding a set of DCOE 18s that were pretty far gone would be helpfull. Most of the info I've found on webers has been related to just tuning, not so much rebuilding.

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Most if not all folks here don't use the choke circuit. Since it's the cam piece I would make sure the parts that follow are in the off position and won't move on there own. I haven't recently looked at a diagram but I would think you are fine assuming it's in the off position. Pierce manifolds stocks all kind of parts. I would guess $15 bucks each for the broken parts.

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Just pulled my Fairlady out of winter hibernation.  This past winter I mated a 100k mile L28 stock block to an E31 head with mild port & polish work, new valve guides, 280z valves & an Isky 290/490 regrind cam.  Triple 45 DCOE 152 [spain] Webers that are pretty new [from Evilc] and a header/exhaust from Sean Dezart in France.

 

I welded in a bung for a wide band O2 sensor but haven't plumbed the gauge yet.

 

specs for my triples

145 Mains

155 air correction

36 chokes

F16 emulsion tubes

45 accelerator pump jets 

55F8 idle jets

4.50 auxillary venturis

 

Today while checking the above specs [hope I have ID'd correctly] I checked the idle mixture adjustment screws.  From L>R they were; 2.5, 2.25, 2.75, 2.75, 2.25, 2.25 turns out.  I only have a few miles on it but looking at the header coloring i have more blue in the middle cylinders than outboard.  Think that's lean?  When idling it sounds like it slightly missing [new plugs], pops when cruising along and pops under deceleration.  It really pulls nicely and sounds awesome under mid to full throttle, once it climbs above 3k rpm's.  My timing light is broken so I'm unable to check that and until I finish the wide band info is lacking.  Currently it prefers rapid but not stomp on it throttle input and if I provide too little input begins to die.  Ahh, the fun of sorting it all!

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