Weber tuning with Lambda sensor - Page 12 - Alfa Romeo Bulletin Board & Forums
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post #166 of 201 (permalink) Old 08-30-2019, 09:24 AM
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200s are going in next and back off the timing to 35. Thoughts? Thanks
That is what I would do. Ignition timing should have little if any impact on AFR.

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 #167 of 201 (permalink) Old 08-30-2019, 12:03 PM
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Thanks Ed, always nice to have confirmation. I did back off to 35 max and brought it in with [email protected], [email protected], and [email protected] The 200's done good.
4th gear cruise [email protected] cruise
3rd gear [email protected]
2nd gear [email protected]
3rd gear progression
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Not as good as logging but stepping frame by frame in my editing program got me there. Now only if the guys at 123 or the afr folks would BlueTooth all this data and bring it into one unit we'd be sitting pretty. btw I got 10 Fine-Thread 18-8 Stainless Steel Thin Hex Nut, M10 x 1 mm Thread from McMaster for the windage tray and they worked great in lieu of the pal nuts on the main caps. Also got longer 7mm bolts for the oilpan to make up for the thickness of the tray and extra gasket. You saved me on 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 #168 of 201 (permalink) Old 08-30-2019, 01:05 PM
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That looks pretty good no 10's or 13's anywhere and 12.8 at the top.
Did you measure the CR?

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 #169 of 201 (permalink) Old 08-30-2019, 04:31 PM
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I did not measure the CR and have not done a compression check. I did take a sample of my first oil at 1000 miles and send it to Blackstone Labs for analysis. Mainly to check for the absence of any bronze from the oil pump drive gear. I'll post the results when I get them.

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 #170 of 201 (permalink) Old 08-30-2019, 08:00 PM
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This is interesting stuff. Mike, what size venturis are you using? What is the ambient temperature when you do your runs? Good numbers and impressive sound and acceleration.

Rich Hanning
'65 Sprint GT, '78 Spider, '88 Quad
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post #171 of 201 (permalink) Old 08-31-2019, 07:30 AM
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Thanks, I appreciate.
When I did those last runs yesterday afternoon it was 95 degrees. We had a mini front move through last night which brought lower temps. Normally the lows are 78 with high humidity. This morning it's 75 and low humidity. Really nice actually! I just got back from a couple of runs and got some 13s up top. I don't know if the temp had anything to do with it but I wanted to double check my numbers from yesterday. I'm glad I did.
As it stands now I'm at:
DCOE 32s
34 venturis
50f8 idle
f11 tubes
135 mains
200 ac
I'm not sure if I have any 195 ACs. If I do I'll try them first then go with a 140 main jet. 140 seems awful big though.

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 #172 of 201 (permalink) Old 08-31-2019, 08:22 AM
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AFRs

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At 6500 in 3rd I have 13.7 which is lean obviously and the advance is 37 degrees.
Actually 13.7 isn`t a "lean" mixture as such. 13- 13.8 is my target in the race cars for power.

I would attempt to lean the 11s a bit to get over the rich range for better power.

Typically your cruise AFRs should be in the mid 13s to 14. And idle (no load) is rich. Have you tried closing the idle mixture screws a quarter or half turn.

145 F8 idle jets?? Never had such small idle jets work in any Alfa.

Richard Jemison
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post #173 of 201 (permalink) Old 08-31-2019, 08:41 AM
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Thanks Richard. I'm since gone to 50f8 idle jets and adjusted for high 12s to 13 at idle. With the temp being 75 this morning as opposed to 95 yesterday in third gear @ 6300 the afr is 13.2
From reading the Weber book it appears to me the F11 tube is richer than a F9. fewer holes and smaller diameter, less air more fuel=richer. IF I'm reading correctly. So I'll stay with the F11.

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 #174 of 201 (permalink) Old 08-31-2019, 06:26 PM
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Thanks for the specs. Your ambient temperatures are very similar to mine. I am going to hold the current setup static for now but may try 34mm venturis in a few months.

At 3000 rpm in fifth gear, part throttle, AFRs are in the high 14s to mid 15s. At 4000 rpm in fifth, part throttle, the AFRs are in the mid 14s. Suspect there will be some jetting changes required after the temperatures cool down.

Rich Hanning
'65 Sprint GT, '78 Spider, '88 Quad
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post #175 of 201 (permalink) Old 09-01-2019, 01:35 AM
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Quote:
Originally Posted by gigem75 View Post
From reading the Weber book it appears to me the F11 tube is richer than a F9.
You're right, but F11 is more than just 1 step richer.

Order is, from rich to lean: F7 F8 F2 F11 F16 F15 F9.

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post #176 of 201 (permalink) Old 09-10-2019, 04:19 AM
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Stable RPM plot from ZT2

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Originally Posted by 65Sprint View Post
Hopefully it is appropriate to post some Dellorto tuning results here. If not, I trust the moderators will advise.

I have been setting up a pair of DHLA 40Ls (emissions carbs) in the '78 Spider with a modified 2L. The engine came from Ed Prytherch and is essentially the same as the first engine Ed describes in his "79 Spider on the Dyno" thread. That is, it has Venolia pistons, 10.6:1 compression, a Richard Jemison head, and Richard's 575 intake cam and 785 exhaust cam. I thought it might be useful to post the jetting specs and results and solicit comments.

The original jetting was, as far as I can determine, stock for a 2L Alfa.

148 Main Jets
57 Idle Jets
210 Air Correctors
32mm Vents
7848.3 Aux Vents
41 Pump Jets
7772.1 Emulsion Tubes
8.5g Float

After a fair amount of experimentation, the current jetting is:

140 Mains
60 Idles
195 Air Correctors.

The following graphic shows AFR by RPM in 2nd through 4th gear. These Dellortos seem to go a little rich after about 5700 rpm. Larger air correctors can keep the AFR in an acceptable range but if too large, the AFRs are too lean around 5400. Of course a larger main jet can be used along with larger air correctors but the same "rich" trend occurs at slightly different engine speeds. The current setup seems to be a reasonable compromise. Comments?
Hi. Nice stable logging output you have there! I also have a ZT2 and am really struggling to get *any* rpm signal, notwithstanding the issues discussed previously with respect to taking a noisy analogue signal from the -ve terminal of the coil....

Can I ask how you connected your ZT2 and what source you are using for the RPM input?

I contacted Zeitronix about the 99999 rpm I am currently seeing and they suggested I have a "ground loop" issue and that I should "connect the brown wire to the coil". The brown wire in their documentation is shown as the sensor ground - the RPM signal is not coming from a sensor though? Where on the coil would folks suggest I connect the brown ground wire to? Is it preferable to just connect this straight to the battery negative terminal?

At the weekend I observed 10 and 11s as the AFR when accelerating WOT in 3rd, which gradually leaned out as the rpm rose. For reference I'm using a ported 2 litre nord with stock valves, Richards cams (RJ 785 intake) and 40 DCOE 28s where the venturis have been profiled correctly and are now 33m diameter.

MJ 130
AC 180
IJ 55F8

I was running 55F9 and a 135 MJ, so switching to the combo above has given me a bit more urgency in the mid range, as I'm not running as rich. Without being able to log RPM, I'm having to glance over at the laptop every few seconds, which is sub optimal from a safety perspective, even on rural UK roads!

Thanks in advance.
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post #177 of 201 (permalink) Old 09-10-2019, 06:06 AM
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Hi. Nice stable logging output you have there! I also have a ZT2 and am really struggling to get *any* rpm signal, notwithstanding the issues discussed previously with respect to taking a noisy analogue signal from the -ve terminal of the coil....

Can I ask how you connected your ZT2 and what source you are using for the RPM input?

I contacted Zeitronix about the 99999 rpm I am currently seeing and they suggested I have a "ground loop" issue and that I should "connect the brown wire to the coil". The brown wire in their documentation is shown as the sensor ground - the RPM signal is not coming from a sensor though? Where on the coil would folks suggest I connect the brown ground wire to? Is it preferable to just connect this straight to the battery negative terminal?
I am using a Marelli-Plex ignition on the '78 Spider and use -ve on the coil for the tach input. Ed Prytherch (alfaparticle) built an interface to protect the ZT-2 from voltage spikes so the wiring for tach input is -ve on the coil to the interface, output from the interface to the green input wire for the ZT-2, and ground wire on the interface to chassis ground. All other connections are per the ZT-2 instructions with a common ground to the chassis. I don't understand the advice to connect the brown wire to the coil to solve a ground loop. Ed may be able to shine some light on this issue.

Rich Hanning
'65 Sprint GT, '78 Spider, '88 Quad
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post #178 of 201 (permalink) Old 09-10-2019, 07:23 AM
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I spoke with Mark Robinson yesterday and he is also using the same interface circuit with a Pertronix distributor and a ZT2 and he has good rpm plots. I think that I posted the circuit on the ABB.
Make sure that the ground wire to the ZT2 is a very good one. "ground loops" are often associated with high resistance in that circuit.

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 #179 of 201 (permalink) Old 09-10-2019, 07:41 AM
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Here is the protection circuit https://www.alfabb.com/bb/forums/car...ml#post7066409

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 #180 of 201 (permalink) Old 09-10-2019, 07:52 AM
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Thank you Mr. Hunt. I guess that keeping out of the 13s AFR @wot with an F11, 135 mains, and 34 venturis means my headwork must be doing something right. btw I ran a compression check yesterday and got 195 psi +- 5 psi on all four. I don't recall exactly without looking it up but my LCs are 104 on each cam. 472 intake and 785 exhaust.
I don't know if anyone has used the Track Addict app but it is pretty slick. It gives you 0-60 times, 1/8th, 1/4 mile times in the drag mode and in the track mode it records times, accel, braking, etc. I'd been using the free version and just plunked down my $8.99 for the pro version so I can record more than three sessions. I got a 5.3 second 0-60 time in my Giulia and I'll give the GTV a try next. finger's crossed

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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