Weber tuning with Lambda sensor - Page 5 - Alfa Romeo Bulletin Board & Forums
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post #61 of 188 (permalink) Old 11-09-2014, 08:28 AM
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Returning to my efforts to lean out my AFR below 5000 rpm. I exchanged a couple of PM's with eedneco and I may modify my emulsion tubes. I will wait until I have the exhaust modified and maybe install full radius horns as they may take me in the right direction. I think that drilling additional holes high on the tubes should lean the mixture at the lower end of the main circuit. It is a downside of emissions Webers that there are only 3 emulsion tubes available for them.

Ed Prytherch
79 Spider
76 Suzuki GT500
2011 Jaguar XKR

A little government and a little luck are necessary in life, but only a fool trusts either of them. - P.J. O'Rourke
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post #62 of 188 (permalink) Old 11-16-2014, 12:08 PM
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I retarded my timing to 32 max and it runs better than ever.
135 main
50 f8 idle
F9 emulsion tubes
200 AC
32 chokes
4.5 aux venturis

Even before I changed the ignition timing I noticed a very quick lean out begining at 6200. Right below that the afr showed mid 12's. Within the space of 100 or so rpms it jumped to the mid to high 13's. Kind of scary actually.
From what I've tried to soak in changing to a f11 emulsion tube should help. There is no "B" hole at the bottom so no braking action at high rpms = richer, Correct? Any comments, suggestions would be appreciated. I don't usually run up there but seeing that lean out got my attention. Head is ported similar to my "headwork" thread. HD valve springs, big intake valves, opened seats, exhaust valves are stock. Shankle headers.

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the ones that got away:
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post #63 of 188 (permalink) Old 11-16-2014, 01:38 PM
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I doubt that the emulsion tubes are affecting the top end. I would try 190 or 180 air correctors. I probably have some that I can lend you if you are not starting a jet collection.

32 advance is not much. I am at 34 with higher compression. I tried 32 on the dyno and lost power. Tried 36 and it was the same as 34.

Ed Prytherch
79 Spider
76 Suzuki GT500
2011 Jaguar XKR

A little government and a little luck are necessary in life, but only a fool trusts either of them. - P.J. O'Rourke
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post #64 of 188 (permalink) Old 11-16-2014, 02:16 PM
Richard Jemison
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AFM

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Even before I changed the ignition timing I noticed a very quick lean out begining at 6200. Right below that the afr showed mid 12's. Within the space of 100 or so rpms it jumped to the mid to high 13's. Kind of scary actually.
I suspect a quick reduction in AFR is due to inadequare fuel supply.

I would see if Ed`s smaller ACs work but my guess is it will lower the RPM that the leaning out starts, as I would expect richer mixtures at all RPM as a result.
Then go back to 200 ACs and put in 140 main jets.

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RJR Racing

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post #65 of 188 (permalink) Old 11-16-2014, 03:23 PM
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Thanks, if I may think out loud some theory...in Pat's book he talks about the emulsion tubes and the braking action of the air bubbles. The B hole on the bottom induces bubbles that affect top end mixture. The f11 tube has no B hole and therefore should not brake the gas and thus give a richer mixture at the top end. Everywhere else it's fine I only want to affect one specfic range. The AC's if I read the book correctly will add more air over the whole range even at the top which will advance or retard when the progression from idle jet to main jet occurs. If it doesn't work that way how does it? Don't get me wrong I appreciate being advised as to what to do but I want to understand why. Thanks

The passenger seat is 15 miles an hour faster than the drivers seat.

currently
2017 Giulia Q4
74 GTV restored daily driver
71 Berlina in 2L restored driver
the ones that got away:
1959 750 series Giulietta Spider Veloce
1962 Giulietta Spider normale
1965 Giulia Sprint normale
1972 GTV
1974 GTV
1974 GTV
1977 Spider
1974 Spider
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post #66 of 188 (permalink) Old 11-16-2014, 03:32 PM
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None of the mix is a true constant. It varies a bit (within limits) as vacuum increases or decreases. It is not nearly as difficult to set up a DCOE for a constant engine speed and load, be that 3,000 rpm or 7500. It's the changing vacuum at changing engine speeds with variable load that will always lead you to think of fuel-injection...


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post #67 of 188 (permalink) Old 11-24-2014, 05:47 PM
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My lean out at high revs was a myth. This is my redneck dyno and has if nothing else told me I'm not leaning out.


The passenger seat is 15 miles an hour faster than the drivers seat.

currently
2017 Giulia Q4
74 GTV restored daily driver
71 Berlina in 2L restored driver
the ones that got away:
1959 750 series Giulietta Spider Veloce
1962 Giulietta Spider normale
1965 Giulia Sprint normale
1972 GTV
1974 GTV
1974 GTV
1977 Spider
1974 Spider
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post #68 of 188 (permalink) Old 11-24-2014, 06:01 PM
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If anything (and assuming I'm seeing the numbers right) it looks like you're a tad rich at lower RPM WOT, looks good at the high end. If the car's running well not sure I'd mess with it: you can drive yourself crazy with Webers and an AFR meter!

Tom

1963 Giulia Spider (1750 engine)
1974 GTV
1991 Spider
Former: 1987 Milano Gold
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post #69 of 188 (permalink) Old 11-24-2014, 06:16 PM
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I should have some more to post in a few days. My Spider now has a 2.25" exhaust with a single straight through Borla muffler. It is a bit loud but not as bad as the resonator/stinger combination that I tried. It will be interesting to see if it causes the AFR to lean out anywhere.

Ed Prytherch
79 Spider
76 Suzuki GT500
2011 Jaguar XKR

A little government and a little luck are necessary in life, but only a fool trusts either of them. - P.J. O'Rourke
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post #70 of 188 (permalink) Old 11-25-2014, 04:40 AM
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I'd like to hear that! Seriously, I'd like to hear that.

The passenger seat is 15 miles an hour faster than the drivers seat.

currently
2017 Giulia Q4
74 GTV restored daily driver
71 Berlina in 2L restored driver
the ones that got away:
1959 750 series Giulietta Spider Veloce
1962 Giulietta Spider normale
1965 Giulia Sprint normale
1972 GTV
1974 GTV
1974 GTV
1977 Spider
1974 Spider
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post #71 of 188 (permalink) Old 11-25-2014, 01:34 PM
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Noise!

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I'd like to hear that! Seriously, I'd like to hear that.
Hey Mike - just for you I read the camera manual and figured out how to do it. You had better appreciate it.


Ed Prytherch
79 Spider
76 Suzuki GT500
2011 Jaguar XKR

A little government and a little luck are necessary in life, but only a fool trusts either of them. - P.J. O'Rourke
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post #72 of 188 (permalink) Old 11-25-2014, 01:59 PM
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This is the new exhaust. The Shankle collector was cut off "upstream" of the original 2" pipe so that there was no diameter reduction before the new 2.25" pipe. The muffler cost about $65 from Summit Racing.
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Ed Prytherch
79 Spider
76 Suzuki GT500
2011 Jaguar XKR

A little government and a little luck are necessary in life, but only a fool trusts either of them. - P.J. O'Rourke
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post #73 of 188 (permalink) Old 11-25-2014, 05:30 PM
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Sweet!!

The passenger seat is 15 miles an hour faster than the drivers seat.

currently
2017 Giulia Q4
74 GTV restored daily driver
71 Berlina in 2L restored driver
the ones that got away:
1959 750 series Giulietta Spider Veloce
1962 Giulietta Spider normale
1965 Giulia Sprint normale
1972 GTV
1974 GTV
1974 GTV
1977 Spider
1974 Spider
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post #74 of 188 (permalink) Old 11-27-2014, 01:58 PM
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I have posted AFR data here http://www.alfabb.com/bb/forums/spid...ml#post5897649

Ed Prytherch
79 Spider
76 Suzuki GT500
2011 Jaguar XKR

A little government and a little luck are necessary in life, but only a fool trusts either of them. - P.J. O'Rourke
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post #75 of 188 (permalink) Old 11-28-2014, 03:17 PM
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A perfect weather day for some good runs.
Will do 130's tomorrow, same run


The passenger seat is 15 miles an hour faster than the drivers seat.

currently
2017 Giulia Q4
74 GTV restored daily driver
71 Berlina in 2L restored driver
the ones that got away:
1959 750 series Giulietta Spider Veloce
1962 Giulietta Spider normale
1965 Giulia Sprint normale
1972 GTV
1974 GTV
1974 GTV
1977 Spider
1974 Spider

Last edited by gigem75; 11-28-2014 at 04:17 PM.
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