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

[didier]

I'm still quite convinced the setup to have is Extrudabody ITBs with Electromotive ignition... You get what you pay for.

 

(I'm not made of money either, which is why this is on my wish list and not on my car. That said, when I finally move on from my DCOEs, I'm going to be moving UP!)

 

Extrudabody is a good product, Jenvey , too, but Electromotive ECU has nothing better than Mégasquirt2 or 3 .

If you really want the best without price consideration, go with MOTEC,world leader in racing .

[zredbaron]

If you really want the best without price consideration, go with MOTEC,world leader in racing .

 

I'll have to look into that, thanks.

[duragg]

This week my DCOEs are dialed in PERFECT!

Man they love the cold weather.  I checked all the airflows and they were perfect.

Tweaked a few idles and reset for 1000 RPM and the car is in heaven!

 

Summer bad...

Winter good...

[turbeau]

Here's my setup:

180 air corrector

F11 emulsion tubes

140 main jet

55 F8 idle jet

45 Venturi

34 choke

 

Does anyone is the San Diego area have a synchro meter I can barrow for a day?

[AZGhost623]

I have triple Weber DCOE45's. Here is my setup. Has yet to be tested, but came from Topendperformance.com based on engine setup.

 

36 chokes
145 mains
155 airs
55F8 idles
F16 Tubes
00 Pump Bleeds
45 Pump Jets

 

[turbeau]

2 posts above this I posted my jets. The car ran bad. Idle was very stable at 900 RPM but anything over 30% throttle would make it bog. There was a huge cough at the transition point between between 2-3k RPM. If I got through the bog at the start and all the coughing at the transition then it was a little more stable up to 6000, with an occasional hiccup. All these problems made the car very slow and no fun to drive, almost dangerous in traffic cause I was always bogging all the time.

 

Yesterday I went to a dyno day at a local shop. I knew I wouldn't be able to make a clean run because of how the engine was running, but I wanted to check the AFRs. I suspected it was very rich because the plugs were always black and sooty. Well the dyno said it was very rich at idle, about 10, and very lean for the rest, about 15-17. I moved the idle mixture screws in until the idle AFRs were closer to 12. Then it was time to do something about the rest of the range, luckily there is a buggy shop next door that sells Weber parts. They happen to have 6 145s mains that I buy and install. I assumed that this would richen up the the top end be a good start to making the car more driveable. I was expecting only a very small difference.

 

Well, switching to the 145s mains fixed everything, I swear. There was no bog at any throttle input, no nothing at the transition except clean pulling. I could not believe the difference. I wanted to find a weakness and I knew that a burnout was completely out of the question with the previous setup, it would seriously bog for 2-3 seconds.  So I came to a stop, brought up the revs and dropped the clutch. Whoa! Tires instantly lit up and spun all the way to second gear. 

 

I have been driving around town today and the car is almost boring. From a stop light in traffic I just give it a little gas and the car goes, shift at 3000 and keep going with no problems. Then when there are no cars in front of me Ill take it up to 6000 and the car just screams. 

 

Before the jet swap I was very dissatisfied with the carbs. I have heard far more stories of people having problems with bog and poor transitions than Webers that worked properly. So if you are like me from two days ago then take hope that even a small change, like one jet up or down a step, can change the character of the entire car. 

[Lazeum]

Good to hear that. I'm quite surprised with the output but if it works, everything is fine.

 

From my young Weber experience on L6, f8 idle jet are a little bit on the lean side. I had much better results with f9 that provides richer mixture. If it works for you now, don't change anything, I'm just saying.

 

Have you also sync your carbs? Since I've done mine carefully, the engine runs much smoother at idle & low loads.

Edited February 11, 2013 by Lazeum

[turbeau]

Now that it's running well I want to do another dyno pull then see if anything needs to be changed.

 

I have a sync tool but have not been successful using it.

Here is what i tried. I disconnect the linkage, use the idle speed screw to get the flow about the same. But each barrell of the carbs are reading different. Then when I connect the linkage rods they will not be the same length. The closest I could get the carbs is 4-5-7 on the sync tool. The idle mixture screws seem to have no affect on the flow, or the idle speed for this motor.

[duragg]

The idle "speed screw" sets the position of the butterfly and it really should be direclty under the progression port closest to the engine- RPM be damned, it will be what it needs to be.  This position allows best throttle tip-in response as the butter fly JUST moves, it begins to pull fuel from that prog port.  On some carbs this will make an unacceptably high or low rpm (>1200 / <700) in which case prog port modification can be done which I had to do.

 

Later carbs have a balancing screw so you can match one barrel of each carb, then match the other barrel with the balance screw by opening it a little.  So ideally one balance is always closed, other may be open just a touch.

 

And yes, as you tighten it down it all moves out of balance, so you start over (fresh cold beer about now) and you may have to "lead" the error to get it all locked down just right. 

 

This may help:

[AZGhost623]

Since my car is road worthy now, and some drive testing and reading A LOT, I have convinced myself the venturis/chokes are too big. I have DCOE45's with the following setup on a big bore high compression engine (flat top 89mm pistons, .080 thousandths headshave, F54/P90A)

 

36 chokes
145 mains
155 airs
55F8 idles
F16 Tubes
00 Pump Bleeds
45 Pump Jets

 

Cold start is extremely hard by itself. Place hand over air intake horns to create bigger vacuum, and car starts immediately (or use starter spray with butterflys cracked and same result). Car LOVES high rpm (4000 rpm+) but sucks on the street. It idles great, and rev's great with quick blips just fine which is weird. But mash on the gas and there is a problem at low rpm with a load on the car. I think I should move to 34 or even 32 size Venturis. Can someone else confirm my sanity check on what im seeing? 

Edited April 1, 2013 by AZGhost623

[Leon]

Go to Sidedraft Central and read (and absorb) as much as you can. Rest. Read some more.

 

Otherwise you'll be chasing your tail, or as TJ shows above, herding cats...

[duragg]

I do think starting with a small and managable choke and working up from there is helpful.

But as we discussed by email, a change in choke changes everything else so you are switching Main, Air and possible idle and other jets.

[AZGhost623]

The more information the better I have to combat the situation is the way I look at it. After talking to TEP this morning who originally sold me this setup, he wants to change out the main jets and idle jets to something bigger to account for the more intake in air. Im not too sure this is the right way to go in my opinion, bigger is not always better. He still hasnt gotten back to me yet, and I may go look somewhere else. To me its not pulling enough vacuum on that large of an intake so the choke needs to be changed as well.

The hard part is I dont know how to calculate what my displacement is, or how much CFM im moving so trying to figure out the correct idles/mains is a bit challenging. The snail gauge shows me 7 across all carbs now, but Im not sure what exactly that means in a sense of trying to calculate CFM and displacement to get the proper sizing. Last thing I want to do is just randomly throw money at it, it can get expensive fast that way.

[Lazeum]

Before getting some conclusions about your carb setup regarding airflow based on simple test, I believe it could be worth it to check AFR & timing.

If the carbs are well setup the way they are now, very small difference between main & air jet are a sign something is not right. I have the opposite issue: too small chokes.

 

I do believe 36mm choke are however on the high side, especially on 45DCOE.

[AZGhost623]

I have an electromotive ignition, so no distributor. Im at 16 degrees at idle. 36 total advanced. its money on the idle. I have tried a few degrees higher, and a few degrees lower, and it really likes being at 16 degrees, its quite noticable with no studering and coughing/choking. The higher end, Im not too sure on, I have just heard 36 degrees at full advance is where its needed so I have set that. I havent messed with the timing on the upper limit at all. I can rev it up at idle and it sounds great. if I should be somewhere else, i can definately try it out. I have the AFM o2 wideband gauge so that has been helping me out a lot letting me know whats going on.

[duragg]

The Z engine calculator will get you close:

http://www.atlanticz.ca/zclub/techtips/calcs/engine%20builder/

If you have 89mm bores and standard rods you are somewhere around 2950cc?

 

Use the snail gauge only as a reference for comparing and setting all the bores to the same flow.

Those values go out the exhaust as soon as the butterflies move.

[Lazeum]

Ok, for timing. with your P90 quench head, some lower timing could help but only dyno time or trials on the street with something to measure performance would tell you if you're fine. Your problem isn't related to timing at high rpm anyway.

 

If you have a AFR sensor, what does it say when you're driving the car on the streets? Does it bounce around? do you see anything suspect such as too high AFR?

 

Your issue could be a too large choke but it could also be an idle jet not appropriate. It was with 40DCOE but a friend running xxf8 idle jet was running very poorly until we've switched to xxf9, which were providing much better mix during progression mode. With a wideband, you can see too high AFR when using little pedal throttle.

In your case, I would try 50f9 instead of 55f8.

 

Your emulsion tubes could also be a reason but I wouldn't mess with them; they cost a lot & F16 are known to be usually very fine for gasoline. For information, I'm running F11 tubes with success.

[Leon]

E-tubes are key, and pretty much all of them suck on the DCOE. Apparently, the F7 is most promising (after plugging top holes) but I'm using Keith's tubes on my 40s and will do the same with the 45s once those are on an engine. Throttle response is great all around.

 

When the car is back on the road this month, I'll have to shoot a video.

[AZGhost623]

AFR Sensor goes way up when its stumbling. Idle AFR varies a bit between 13.2 and 13.8 Here is a video I took over the weekend with a family member. 42 seconds in, you can see the surging, and 1:30 in there is some other weirdness. http://www.youtube.com/watch?v=SPAeR4dG1tw

 

But it rev's real good http://www.youtube.com/watch?v=RzU3wvpMpaI

 

Interesting on the emulsion tube. Ill have to read some more on that on why they are key?

 

I got some free parts coming from a friend of a friend who has DCOE 152's on his Porsche, so I cant complain. Ill swap it out with this stuff out later this week or this weekend and see what happens. He also agrees the 36 choke is way too big for this car. His opinion is that this setup is for a track car to have constant high rpm's, not street use. He thinks that this will make a good street tune. He has a large swath of parts I found out so Im free to use if needs be to find the right tune and then pay him on what I do decide to keep.

 

32mm chokes

140 main

165 air

Edited April 2, 2013 by AZGhost623

[Leon]

Like I said, go to Sidedraft Central and browse the "Files" section. At the very least, read the White Tuning Paper.

 

You're shooting in the dark otherwise.