Wideband Results

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First thing seal up the cold start valves.

Next, set LBI HOT.

There's nothing wrong with the 009 per se, but it may take more pump squirt to remove that lean spike you are seeing. SVDA attacks the same issue with more advance instead.
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[71sbeetle]

[rbp]

What does the other car idle at?

If I set for LBI and add 1/2 turn of fat I am in the low 11's for sure. I pressure tested the carbs and there are no leaks anywhere that I can find, I even changed the float ball valves to be sure.

Some use the JB weld to seal the chokes. Mine were factory sealed, can't blow air through any passage related to the chokes.

Not sure what my issue is but now I am just setting for LBI, adding just a bit of fat and sit in the mid to high 12's at idle.

[71sbeetle]

[rbp]

So both your cars are running at low 11 LBI?

[71sbeetle]

Yeah but the other one I need to reset idle set screw now that I have a vacuum gauge not sure if it'll make a difference or not
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Alte Schule Vintage and Performance VW club
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[RHough]

Lean hole swallowing my Ghia!

1967cc
w-120 cam
9:1 comp
L5 heads w/matched manifolds
CSP Python with 1 1/2" primaries and 1 5/8 collector cone
Petronix SVDA dist with full adv set 28°

IDF 40's
32mm Vents
1 5/8" Velocity stacks inside 2 1/2" tall filters.

Ghia - 2111 lbs with fuel and driver

3000 RPM cruise in 4th is about 100 kph (60 something)

It gets 11 MPG

I have been chasing this with idle jets from 47.5 to 52.5
LBI is:
47.5's 1 1/2 turns out
50's 1 - 1 1/4 out
52.5's 7/8 turn out

If I set idle screws to peak RPM I read 15-16:1 AFR. I back them out 1/16 - 1/8 from that. Backing them out a full 1/2 turn from LBI results in a hugely rich mixture from idle to flat spot. The throttle response is rotten when the mix is that rich.

Accel pumps backed off as far as possible without the nut falling off. Every time I try more pump stroke I get a rich stumble before the lean hole.

Tip in from idle gets 11:1 AFR

There is a HUGE lean spot at the end of transition from the low speed circuit to the mains.

With 28mm vents and 50 idles it went to 16.5-17:1 before going rich on the main circuit.

With 32mm vents and 50 idles it went to 18+

I rechecked float levels when I swapped the vents: 10mm

The vacuum signal is about 2" at cruise. It maxes at about 5" before dropping under heavier loads.

In an effort to get some sort of reasonable cruise mixture like 15-16:1 I tried this:
47.5 idles
135 mains
180 AC
F7 tubes

Result is still too rich at cruise loads, 20:1 undrivable lean spot, too rich on the main circuit.

I have F11 & F7 tubes, 180 & 200 AC's, 47.5/50.0/52.5 idles, 115 to 135 mains, 28 & 32mm vents to try. No combination of tubes and AC jets that I've tried eliminates the lean hole / too rich cruise condition.

I can get LBI with any of the idle jets. All of them are way too rich below the lean hole. The idle to hole response is best with the 47.5's and the hole is so lean the car is undrivable. The 47's,50's,&52's are *all* richer than 12.5:1 from off idle to the hole. The bigger the idle jet the richer the mixture and the smaller the hole.

Based on the vacuum advance port readings I have and the wideband data I'm seeing this is what I think is going on: Cruise loads are so low that the throttle plate is not open far enough to give full vacuum advance. The load is so low at cruise the only the low speed/idle circuit is in use.

I don't see a way to lean the cruise mixture without making the lean hole bigger.

Driveability with the 52.5s and the pumps backed off is okay. I'd hate to think that the engine/car combo is doomed to a life of 11:1 mixture just to mask that super lean transition.

With the stock DP 1600 and the 40 IDFs the car gave 25 MPG+ with the standard 28/200/F11/115/50 setup. This engine gets 12 MPG with the same carbs, same timing, and same exhaust.

What am I missing?

Thanks for reading through this.
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92x74-1967cc; 9:1; L5 Heads; W-120; 1 1/2" CSP Python; Weber IDF 40

[[email protected]]

"Full advance at 28", is this with the vacuum hose on or off?

Should be hose off, which is ~8BTDC at idle. At idle putting the hose on/off should NOT change the idle timing. If it does the carbs are improperly set up.

Post a picture looking down the carb throats, of both carbs.
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[RHough]

[[email protected]]

what is your ignition timing at idle? I was checking to see if the aux vents were in properly (they are), not upside down (a common problem).

Have you driven around yet for a week with the main/emulsion/air jets removed?

From what you are writing, the problem appears to be a late main tip in, and has nothing to do with the idle/progression. It's a common mistake to try to tune out this problem with the idle jets, when the issue is the main circuit timing.
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It's just advice, do whatever you want with it!

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[RHough]

[[email protected]]

read this thread starting from page 1 all the way through. Then do it another 2x, and you'll know what is going on.
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It's just advice, do whatever you want with it!

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[modok]

If you read the entire thread, and comprehend correctly, you should arrive at this conclusion

Change to
f-11 or f-15 tubes, 140 main, 220 air, 1 1/4 tall latest rage velocity stacks.
http://www.socalautoparts.com/product_info.php/lat...bs-p-16614

Before they arrive, just remove the ones you have. Too close to the lid.

[tzepesh]

Hello John, please give me your opinion on this issue: Engine specs: 1584cc engine, W100 cam, 4-in-1 exhaust, Megajolt ignition based on MAP, Dellorto DRLA36, 30 vents, 52 idles, 180 airs, 9164.2 emulsion tubes, 122 mains.
With #52 jets it is running well, but wideband shows too rich, around 10.
I switch to #50, is is running very bad, with backfire through the carbs, but it shows around 13-14.
If I install #48 jets, it is running ok, no backfire through the carbs, but it is very lean, around 18.

After that, I put back 52s even if it was too rich, but now it doesn't want to idle. It revs ok, but as soon as I let the pedal off, it dies. What would be a reason for this (I checked the jets for clogging and reset the idle mixture screws to 1 turn out, as in the first run when it was ok; also idle speed screws have no effect, no matter how open they are set)?

I expected it to run good on 50s, what would be the reason for such a bad behavior?

All jets are from Alfa1750 on Ebay, I dealt with him in the past and always got the parts I expected, very good quality.
_________________
'74 1303S, L98B Viperngrun (extra glitter), German Look
'64 1200, Sea Blue, under restoration

[TinCanFab]

[tzepesh]

Hey Roachdub, I am well aware of the tuning process, first time I did it was around 4 years ago, also with help and explanations from John, reading through all the ~25 pages at that time.
MAP is around 65 at idle, timing is set at max 32 degrees, advance curve is similar to 009 for start and only RPM dependant, not load. I can not install a distributor now, I am mising all the parts, but ignition is working flawlessly, also checked it with a timing light. Vacuum is taken from the intake runners, below the throttle plates, and the pipes go to an equalization chamber and then to MAP sensor.
I have dual carbs. I started with balanced carbs and adjusted idle screws, but I just wanted to tune it better (as I said, 52s show too rich, 48s too lean, and 50s show alsmost stoich but it pops). Whenever I switch the jets I also set the idle speed screws to 1 turn in. I checked the carbs on bench and with throttles fully closed they draw the same. Floats is set right (I just re-checked it, I did not have to alter the old setting). I can not measure the fuel pressure as I can not easily find a good gauge around here (in Romania tuning is pretty much wrongly understood and fine parts are hard to impossible to find, I usually order from Germany, USA...).
The 50s mostly pop at higher RPM than idle, but it also happens at idle. I was considering bad jets, but they are new and coming from a trustworthy source, and I could not find a jet sizing tool to check those intermediate holes, like 0.47mm or 0.49.

I'm even thinking to re-start the whole tuning procedure, running without main stacks and all...
_________________
'74 1303S, L98B Viperngrun (extra glitter), German Look
'64 1200, Sea Blue, under restoration

[TinCanFab]

[[email protected]]

Measure the jets. Sounds like 1 or more of them aren't sized as marked.

You are resetting LBI after each idle jet change, right?

I would think the proper size would be in the 50 range.

Your old timing map is not going to work with the smaller idle jet, you have to add light load timing off-idle.

Save your old map so you can go back if you stuff it up. Copy it, and change the low load values where you drive on progression. Add around 8-10 degrees, and then re-try the small idle jets after re-setting LBI

[c.ruber]

Much thanks to John C for all his advise with my IDAs. John has enlightened me regarding some mechanical issues besides tuning that was occurring with the carbs. I have addressed those issues, yet I'm chasing my tail with tuning these carbs. I have an Innovate MTXL that I'm using as a tuning tool. My engine is a 2275. The engine specifics are as follows... CR 9.6:1, Web 86B, A1 sidewinder exhaust 1 5/8", DRD stage 6 heads 42X37.5, Berg 1.45 rockers and a Bosch 010 with points. The IDAs are Italian which have had the third progression hole drilled. My current jetting is 37mm venturis, 100 idle air, 60 idle fuel, 180 air correction, F11 emulsion and 145 mains. the accelerator pump squirters are 50s. I cannot seem to be able to get away from the 100 idle air to save my life. The top of the idle circuit will run lean > 13.5:1 AFR if I install an idle air jet larger than the 100, and I've tried 110,120 and 130. If I install the 100 idle air and a 65 idle fuel, the overlap in progression loads up the plugs to the point of causing the engine to misfire. I can also see it on the wideband(9:1-10:1 AFR).
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...and progress is not intelligently planned...

[bugguy1967]

Hey all. I have a few questions as I just purchased a LM2; first, is the 18' oxygen sensor cable recommended to reach from the exhaust to the windshield mount? I have the 8' cable that comes with the deluxe kit, but I fear it may be a little short. Next, I wanted to play around with my basically bone stock 1600 until I have a Weber equipped engine to tune. Where should I weld the bung onto a stock pea-shooter exhaust? What's the best order of procedures to do when actually tuning with a PICT 34-3?

Also, I wanted to ask, does Innovative actually make their own window mount with their logo on it, or is it sourced from China or something. I ordered one on Ebay, and it says another brand on it. When looking up that part number, I could've gotten it for $22. When I search "camera windshield mount", I see similar ones for $10.