Weber tuning with Lambda sensor - Page 11 - Alfa Romeo Bulletin Board & Forums
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post #151 of 198 (permalink) Old 12-24-2018, 11:31 AM
Richard Jemison
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Choosing LCs

Read the latest post on my Technical Questions or the Dynoed my 86 Spider thread today.

What others with cam designs totally different from any other doesn`t have any application to your engine.

What is your engine, induction lengths, use, cams installed, VVT or not, these are the factors that determine where to set cams.
As I posted Stock Alfa cams have excessive overlap at 102/102 if that`s what you have.

It`s X-mas -1 and I`m bored so here`s some info

Here`s the Best of Alfa`s production cams the 10548-01 and
Ed`s current cams in red Intake/exh

10548 03200 01" (Cam Data .401 Max Lift 10.2 mm lobe lift
Cam Lift Dur. at 0 lash. Factory LCs 99.5/99.5)
Ed`s cams
.018 286 (off the seat/lash, Paired overlap at 99.5 LCs is 76
.020 278 degrees, & way too much! at 104/104 = 56 degrees
.040 240
.050 230
.100 211
.200 173
.300 118
.350 83
.400 10

Eds intake & Exhaust cams currently RjR575 int 785 exh and next exhaust cam he`s going to install. (The new exh is an extreme power builder.)
Lobe lift Int,.503(12.8mm) Exh,.461"(11.7mm) New exh.495"
Intake RjR 575-----------------Exh RjR785-----------Exh RjRprivate
,010-304-OTS duration/lash-------------------------------276
.012--------------------------------287(lash/OTC---------------
.020-289---------------------------273---------------------264
.040-273---------------------------252---------------------252
.050-267---------------------------247---------------------246
.100-242---------------------------223---------------------228
.200-202---------------------------186---------------------194
.300-156---------------------------145---------------------156
.350-137---------------------------------------------------------
.400-120----------------------------89----------------------110
.450--81---------------------------125-----------------------65
.500---8---------------------------------------------------------
Overlap with cams set at 104LC each (add intake Overlap to Exhaust overlap for total overlap 105/105 LCs will reduce this overlap about 4 degrees total
27 degs.------------------------18.5 degs.-----------------26 degs.
Paired overlap-------------------45.5 degs.---------------- 53 degs.

Richard Jemison
RJR Racing

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Last edited by Alfar7; 12-24-2018 at 11:46 AM.
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post #152 of 198 (permalink) Old 08-13-2019, 06:41 PM
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I did my redneck data logging AFRs on my new motor with the higher compression Alfaholics pistons. My first runs were with 135 mains and 220 ACs. That was to lean.
Then with 135 mains and 210 ACs which gave me [email protected]
and then 130 mains and 200 ACs which was [email protected] I decided on the 135 and 210. The pull in 4th from 2000rpm was smoother with this as well.
The complete jetting is:
135 Mains
210 AC
f11 tubes
34 chokes
55f8 idle
Ed and anyone else, what do you think. Also posting on my new motor thread.

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
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post #153 of 198 (permalink) Old 08-14-2019, 07:51 AM
Richard Jemison
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AFRs

I did see 10s & 11s in your video, corresponding to "Tip in". AFRs under full power should be in the high 12s or low-mid 13s, other than the 2-3 seconds where the accelerator jets are spraying. Constant speed on level road about 14-14.5, and on "tip in" (accelerator jets spraying) drop to low 12s then leaner again as above.
Idle no load 14-5 -15 AFRs

Per Jim Steck there is measurabe power loss richer than in the mid 12s

Richard Jemison
RJR Racing

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post #154 of 198 (permalink) Old 08-14-2019, 05:48 PM
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Thanks Ed, Richard. There are two different runs with different jets and thus different numbers in the video. I can get 14-15 at idle but it spits back. Best smoothest idle is at mid 12s. 1st gear WOTs are a few points leaner than 3rd wots which are in the mid 13s with the 135 210 vs the 130 200 which is [email protected] in 1st.
It looks like my biggest deviation from the numbers are the cruise numbers @4000 which are high 12s to mid 13s. The ambient temp was 99 degrees and road was not perfectly level. I think I'm pretty close and will do some runs when it cools off. Also had the aircon on too, just to darn hot! It really is my best motor yet, imho.

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 #155 of 198 (permalink) Old 08-14-2019, 06:49 PM
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Idling is not influenced by anything in the emulsion tube stack. I have always ended up using the smallest MJ/AC combo that makes correct AFR at high power and does not go grossly lean anywhere else, but I have not used F11 tubes.
I did almost all of my testing in 3rd gear uphill. When I had found the best setup I did a final run in 4th. Sometimes it went a bit lean at the top and I had to drop a size or two in AC's.
You should do a test run in January to make sure that you are not tending lean.

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 #156 of 198 (permalink) Old 08-14-2019, 08:07 PM
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Roger that! I have to confess, I would have bet money I had as I stated 55f8 idle jets in there but come to find out they were 45f8s. That was a surprise. Anyway I tried 40f8s and could get a good idle, still not 14 though, but the no load cruising was a lot "choppier". I take it easy on the black top road to my house and driveability is a big deal so I went back to the 45f8s. I'm looking forward to the thicker air and no ac load here in 3 or 4 months.

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 #157 of 198 (permalink) Old 08-25-2019, 09:16 AM
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Dellortos - Not Weber

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?
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'65 Sprint GT, '78 Spider, '88 Quad
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post #158 of 198 (permalink) Old 08-25-2019, 11:04 AM
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I would go a little larger on the air correctors. It should not be a problem if AFR hits 13.5 at 5200 so long as it gradually lowers towards peak HP rpm, probably around 6200. Then do a test run, print out the logged curve and draw a horizontal line at 12.8 AFR. Is there more area above or below the curve. If above then go back down on the AC's.

I am jealous of your nice clean rpm signal and I wonder if there is a problem with my Zeitronix ZT2. Maybe we could put my box in your car and see if the rpm log is still clean?

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 #159 of 198 (permalink) Old 08-25-2019, 11:46 AM
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Thanks Ed. I have a log using 210 ACs giving maximum AFRs of 13.3 between 5200 and 5600 rpm. The thought was to keep things just a smidgen rich but sounds like that is not necessary. I will compare areas above and below 12.8.

We can certainly swap your Zeitronix and see if there is a difference.

Rich Hanning
'65 Sprint GT, '78 Spider, '88 Quad
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post #160 of 198 (permalink) Old 08-26-2019, 08:19 PM
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Here are a couple of graphics showing logged AFR curves in reference to a horizontal line drawn at 12.8:1. The first curve was captured while using 195 air correctors and the second was captured using 210s. Looking at the acceleration runs for third gear (in the middle of the graphs) and ignoring the initial variability after the shift, the area below the reference line is clearly greater than the area above the line using the 195 ACs. Using 210 ACs, the areas above and below the reference line even out slightly, which confirms Ed's advice above.
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Rich Hanning
'65 Sprint GT, '78 Spider, '88 Quad

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post #161 of 198 (permalink) Old 08-27-2019, 06:25 AM
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I would use the 195's because of the rising AFR at high rpm with the 210's in 4th gear. My tests have always been up to about 7000 rpm and I have always seen a falling AFR above peak HP with Webers with reasonably correct jetting.

It is interesting that you are much leaner in 4th gear than in 3rd. I have seen that but not as pronounced and it is the reason that I after doing a lot of tuning runs in 3rd gear I do one in 4th to make sure that I do not have a high rpm lean situation. Are you using a high capacity fuel pump and regulator?

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 #162 of 198 (permalink) Old 08-27-2019, 07:06 AM
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Following with interest. Just to clarify, one needs a laptop in the car to log. Correct?

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 #163 of 198 (permalink) Old 08-27-2019, 07:45 AM
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The shape of the curve with the 210s mimics the shape of the curve with the 195s. The second (210) graph above is misleading for the fourth gear run as I had to let off at about 5600. If the run had continued, the slope would have become negative above 5700 or so.

Quote:
Originally Posted by alfaparticle View Post
My tests have always been up to about 7000 rpm and I have always seen a falling AFR above peak HP with Webers with reasonably correct jetting.
Good to know that the behavior of the Dellortos is similar to Webers. Maybe this engine with 32mm venturis and small exhaust makes peak HP around 5600? Lower than I expected, if that is the case.

Quote:
Originally Posted by alfaparticle View Post
It is interesting that you are much leaner in 4th gear than in 3rd. I have seen that but not as pronounced and it is the reason that I after doing a lot of tuning runs in 3rd gear I do one in 4th to make sure that I do not have a high rpm lean situation. Are you using a high capacity fuel pump and regulator?
The curves in fourth gear are certainly flatter than third. A possible, partial explanation is that I have not be able to run the engine to 6500+ in fourth. I expect the AFR would continue to decrease at engine speeds above 6200.

The pump is rated for 30 gph. I confirmed fuel volume output when it was installed two years ago. Last week, the rear fuel filter and the front filter-regulator were replaced to address an intermittent fuel starvation issue. The new filter-regulator is a Filter King with the 67mm bowl and is set for 3psi. There have been no starvation symptoms since those changes however it has not been 95 degrees over the past several days so vapor lock is still a possibility. I don't think fuel delivery issues are currently impacting AFRs.

Rich Hanning
'65 Sprint GT, '78 Spider, '88 Quad

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post #164 of 198 (permalink) Old 08-27-2019, 07:55 AM
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Quote:
Originally Posted by gigem75 View Post
Following with interest. Just to clarify, one needs a laptop in the car to log. Correct?
Yes, I use a laptop with the ZT-2. I think you can buy a dedicated data collector for it.

Rich Hanning
'65 Sprint GT, '78 Spider, '88 Quad

Last edited by 65Sprint; 08-27-2019 at 08:01 AM.
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post #165 of 198 (permalink) Old 08-30-2019, 08:44 AM
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Hope it's ok if I join in....
I can't log data but I can get it. I recorded my screen of the 123 during my runs and recorded the afr's with a tach. Pretty southern but cheaper than a laptop.
At 6500 in 3rd I have 13.7 which is lean obviously and the advance is 37 degrees. If I backed it off to 35 which I think I should do anyway will that change the afr numbers? !'m running 135 mains, 50f8 idle, and 210 AC.
200s are going in next and back off the timing to 35. Thoughts? 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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