engine and drivetrain Need Help! Weber DCOEs Running Rich on Mains. Can't Lean Them Out

[Beach_Bum]

I've installed new DCOE 151 (plastic floats) and am having the absolute worst time trying to tune them. I finally got them to run properly on the idle jets (60 F8). I'm seeing A/F numbers from my WB02 in the 13-14.5 range. I even took the mains out and drove around on just the idles to confirm these numbers. The carbs are in sync and verified with a synchrometer.

 

The problem I'm having is that when they hit the mains, my A/F numbers go rich in the 9-11 range for anything over 1/4 throttle and more than 2,000 RPM. At WOT throttle I'm in the 12-12.3 range.

 

I've changed the jetting from 125 mains/160 airs to 115 mains/200 airs but it doesn't make a difference. I've played with the float level starting with the recommended DCOE plastic float specs (12.5mm closed/25mm at full drop). Nothing. I've lowered the level in the bowl from 29mm from top of the machined surface down to 30mm. Nothing.

 

After searching and reading GreenSwede's thread HERE, I thought maybe I better check my Pertronix to see if it's gapped properly. The gap was a bit large, so I brought it back to the recommended .030 and...Nothing! I even redid some of the wiring to the coil because it looked a little rough. Can you guess what happened? Nothing!

 

Here's my current setup:

1972 2002

Stock motor with IE stainless exhaust and shorty headers

Weber DCOE 151

Tii (002) distributor with new Pertronix

Timing is at 30 degrees at 2,000 RPM on the OT line

Pierburg (Bavaria) fuel pump

 

Jetting:

Choke 32

Main 115

Idle 60 F8

Em Tube F11

Air Corr 200

Pump Jet 40

Needle Valve 1.75

 

I'm running out of patience here. Someone please help I just want the car to run properly.

[downhillwolf]

I hope you have a friend to lend you f9 or f16 emulsion tubes and then try with 115 main and 200 air. but this should make sligth difference. My main concern is what air filter do you have installed? Any picture?

[Beach_Bum]

I hope you have a friend to lend you f9 or f16 emulsion tubes and then try with 115 main and 200 air. but this should make sligth difference. My main concern is what air filter do you have installed? Any picture?

Thanks for the reply. Unfortunately I don't have anyone to lend me different emulsion tubes.

Edit: according to my Weber book, F11 tubes are the leanest.

I'm using the Ramflo air filters. Here's a picture:

Edited March 22, 2015 by Beach_Bum

[downhillwolf]

Thanks for the reply. Unfortunately I don't have anyone to lend me different emulsion tubes.

Edit: according to my Weber book, F11 tubes are the leanest.

I'm using the Ramflo air filters. Here's a picture:

image.jpg

Well, im using F9 or F16 in my 02 and lots of other 02 guys i know they use F9 or F16 as well...

I'm pointing at filters... Because webers and almost all carburetors are vacuum regulated. So bigger the vacuum more fuel inside engine. At higher rews airfilters may block airflow and therefor bigger vacuum inside tube...means more fuel. Try to remove them and take a spin and report of your AFR numbers(dont take off plates too-you may lose your inserts of carb)..

You should be OK without filters, just dont drive it on tarmac...

 

Old unwritten rule from here (Europe) is, that with more throat systems volume of air between throttle bodies and airfilter should be at least 3 times the engine displacement for street engines and up to 5 times for race engine.

So you should have at least 3 litres of air between each carb and your air filter. Also air filters are much more effective with constant flow that with pulsational flow.

Edited March 22, 2015 by downhillwolf

[Hans]

do you have a fuel pressure regulator? Some folks say essential, others say makes no difference. My car won't run smoothly without one. Also, 30 deg adv at 2000 rpm seems a bit extreme - try full advance at 3000 rpm.

['76mintgrün'02]

Total noob question, but could the stock camshaft be 'part of the problem'?

 

The reason I ask is because I have a set of dual carbs I was playing with on an otherwise stock VW engine and I was told that it would be unable to make use of the additional fuel, without camshaft/valve 'alterations'.

[downhillwolf]

Total noob question, but could the stock camshaft be 'part of the problem'?

 

The reason I ask is because I have a set of dual carbs I was playing with on an otherwise stock VW engine and I was told that it would be unable to make use of the additional fuel, without camshaft/valve 'alterations'.

No, carbs are tuned individually with jets, also original 2002 with double dual carbs (2002ti) had stock camshaft as 1502-2002tii.

If you have bigger carbs, you don't use all their potential, to use it engine must be modified with ported head, camshafts etc.

Edited March 22, 2015 by downhillwolf

['76mintgrün'02]

Thank you for the explanation.

Sorry for the distraction.

Carry on.  

[Stevenola]

Agree on air filters, take those off and see if any different.  Do you have any 34mm chokes to try as well?  I had ramflo's but now use trumpets and UNI foam filters, much less restriction.

[ray_]

Agree on air filters, take those off and see if any different.  Do you have any 34mm chokes to try as well?  I had ramflo's but now use trumpets and UNI foam filters, much less restriction.

 

Steve has so much less restriction that he had to add a third carb!

 

:D :D

[zinz]

Per the Haynes Manual, Ti ignition timing is 28-32 degrees BTDC @ 2000rpm.

I'm certainly not a fan of the RamFlo filters, but if you test without them and see a big difference, I would recommend the 6" angled UNI filters, like I have.

Have you checked your fuel level? You may try reducing the fuel level and check you AFR #s.

Sorry to hear you are struggling. I had hoped the bigger idle jets were going to be the end of your troubles.

Ed Z

[Beach_Bum]

I'm pointing at filters... Because webers and almost all carburetors are vacuum regulated. So bigger the vacuum more fuel inside engine. At higher rews airfilters may block airflow and therefor bigger vacuum inside tube...means more fuel. Try to remove them and take a spin and report of your AFR numbers(dont take off plates too-you may lose your inserts of carb).

Agree on air filters, take those off and see if any different.  Do you have any 34mm chokes to try as well?  I had ramflo's but now use trumpets and UNI foam filters, much less restriction.

Wow, filters huh? If that's what it ends up being I'm definitely not telling my wife that the countless hours spent in the garage last week could have been solved in 2 minutes At least I learned a lot about my carbs.

Unfortunately I broke one of my idle jet holders during my frustration, so running without the filters will have to wait. I will report back on Wednesday and let you know how it goes. Thanks for the advice! I don't think I ever would have thought my filters were the problem.

do you have a fuel pressure regulator? Some folks say essential, others say makes no difference. My car won't run smoothly without one. Also, 30 deg adv at 2000 rpm seems a bit extreme - try full advance at 3000 rpm.

I do not. A pressure gauge was most likely going to be my next step.

Per the Haynes Manual, Ti ignition timing is 28-32 degrees BTDC @ 2000rpm.

I'm certainly not a fan of the RamFlo filters, but if you test without them and see a big difference, I would recommend the 6" angled UNI filters, like I have.

Have you checked your fuel level? You may try reducing the fuel level and check you AFR #s.

Sorry to hear you are struggling. I had hoped the bigger idle jets were going to be the end of your troubles.

Ed Z

Thanks Ed. To be honest, I never liked the look of the RamFlos, but got talked into them by Steve at TEP. I was also worried about booster clearance and heard that these left a good amount of room. I like the UNIs and will probably switch to them if need be.

Yeah, I checked the fuel level. I've adjusted it up and down from 25mm-30mm and nothing changes in my AFR.

[Hans]

I believe the ti advance setting was based on having a ti distributor, and using the high octane leaded euro gas available at the time. Maximum advance for ti in Haynes is 39 deg, which is a lot today.I don't see how too much advance would cause these symptoms, but from what I've read of late, the idea is to get full advance of about 33 deg at about 3000.

Fuel pressure regulator should be about 2.5.

[73tiiguy]

Damn Bum, I have to admire your persistence for perfection.  I would have probably just let it go and just lived with it.  Luckily I don't have a wide band sensor, so I have no clue if my AF is even close to the magic number.  I suppose if my motor had performed worse after installing the twin 40's, I'd have gone down the same rabbit hole as you.

 

Try another 02 sensor maybe?

What do your plugs look like, which are you using?

[Beach_Bum]

Damn Bum, I have to admire your persistence for perfection.  I would have probably just let it go and just lived with it.  Luckily I don't have a wide band sensor, so I have no clue if my AF is even close to the magic number.  I suppose if my motor had performed worse after installing the twin 40's, I'd have gone down the same rabbit hole as you.

 

Try another 02 sensor maybe?

What do your plugs look like, which are you using?

 

Haha, you know, as I've been messing with all of this I got to thinking that maybe the WB02 is a blessing and a curse. I see those numbers taunting me from the dash and I just can't help myself to try and get them perfect. After I adjusted the linkage to get more throttle open the car felt pretty good, and if I didn't have the WB02 I probably would have left it alone.

 

I'm running the NGK BP6ES plugs. I haven't checked them yet...another thing on the list of to-dos.

 

I have an unknown coil as well. It came with the car and Google shows that it's a "universal" fit. It worked fine with my previous setup.

 

Edited March 23, 2015 by Beach_Bum