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Discussion Starter #1 (Edited)
I have a 74 Spider with a HP SPICA pump from Wes, 10:1 pistons and 11.1mm cams. I've put on a little over 2k miles since the motor rebuild and am confident that its broken in well and ready to start adjusting for performance.

I have an Innovate LM-2 fuel meter and have been playing with the LogWorks software and taking runs up the hill behind my house. Its a nice straight road thats not too steep, but I can start a second gear pull at the bottom and get to 6K RPM before running out of pavement. Doing that and looking at the log results its pretty consistent.

Here is the graph I have for a couple WOT runs in second gear:

08291401_2ndGearPulls.jpg

My intuition is that this is a little rich with the min AFR of [email protected] and the max AFR of [email protected] - but I'm not sure (this is the first time I've done this kind of tuning).

What is the ideal AFR range I should be shooting for with WOT runs like this?

I'm also using a 123Ignition with the tunable curve, and these are the values I'm running now:

Alfa_Ignition_05.jpg
 

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Great post. I have an HP Ingram pump installed this summer, with 11mm intake and 10.2mm exhaust. I have a 123Ignition not yet installed and a Zeitronix Wideband not yet installed. Following with interest.
 

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Looks fat to me.

Thanks for posting.
 

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Discussion Starter #5 (Edited)
Thanks for the replies!

Yes, both the dyno run and my O2 sensor graph are at full throttle.

The instructions I got from Wes were to adjust the FCS to have it at between 12.5-13.0 @ 2500RPM (with no load) and thats where I started. I've suspected it was running a little rich but have been happy with that while breaking in the motor.

Driving it around and logging the data is a little hard to judge. At partial throttle and light load - it does get up in the low 14s now. But with more throttle and heavier load its definitely down in the 12s a lot of the time.

I'm going to experiment with leaning it out and doing some more runs to compare. The 123Ignition system also has a timer feature that I can use to clock how long it takes to get through various RPM ranges, so perhaps that can give me some more data on whether I'm getting more or less power.

I am a little scared of running too lean and overheating, burning valves or damaging something. How lean really is too lean?
 

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71 Berlina 74 GTV 17 Giulia Q4
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You really won't do permanent damage being to rich, it's best to err on that side rather than lean especially since you won't necessarily hear any detonation from being to lean, maybe just some engine vibration.
People tend to think of detonation and knock as being the same thing. Knock is when the fuel ignites before the spark plug fires, detonation is when the fuel ignites after the plug fires, typically at the edge of the piston and slams into the charge ignited by the plug. Hence the vibration, scuffed piston skirts, and broken ring lands. Knock is cumulative damage occuring over thousands of miles whereas detonation damage is typically instantaneous and catastrophic evidenced by massive blow by.
I've got Wes's delta 12mm intake cam, tried others but none I've tried beats that (for me) ported head, 11mm ex cam, 10:1 motronic pistons, headers, had a HP pump, I was running mid 10's wot on my Innovate with the initial mixture setting of the FCS running the motor no load at 3200 rpm by ear to the sweet spot. With the HP pump the 3200 seems be closer than his book of 2500 rpm. In the final analysis for me plug color has the final say.

38 degrees may be a bit much at 4 to 5000, I'd be interested in what others think? You might see some improvements if you backed off a couple of degrees?
 

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Discussion Starter #7
Thanks, that was a typo above - I meant to say I'm worried about running too LEAN and damaging things. I appreciate your explanation.

Do you know what AFR you are running at 3200 with no load?

I've had some other feedback offline and will experiment with 35-37 above 4k and also take out the decline above 5k.
 

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71 Berlina 74 GTV 17 Giulia Q4
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I don't recall what it was at 3200 and I switched to webs for the current motor otherwise I'd be happy to go look. It's interesting to compare your graph to the curves in the AFR weber tuning thread. I take it you are using the LM2 to log your runs? I am seriously considering one so I can log my data and would like to use a channel for vacuum. Where do you have your cam lobe centers timed, mine are 104 which seems to work well.
 

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Discussion Starter #9 (Edited)
Update...

Just to update this thread with some new info, its running a lot better now.

Here's a comparison between the way it is today overlayed with when I started the post. Its about a point leaner across the board, a little more or less in some places but definitely feels stronger across the whole range. This is a full throttle run in 2nd gear up a straight steep road behind my house.

KR_AFR_HILL_141107_comp.jpg

And here is the current ignition curve:

KR_123_141107.jpg

Looking more closely at the current data, here's a trimmed down graph of the pull and the channel statistics of the AFR. The numbers in the image are not as clear as I would have hoped - the average is 12.2 with a max of 13.0 and min of 11.6 (the previous Max was 11.9!).

KR_AFR_HILL_141107a.jpg

With the way it was setup, I couldn't just turn in the FCS to lean it out at WOT because it was already kind of lean at partial throttle and cruise.

There were two main things that changed - Wes suggested turning in the screw on the barometric compensator by between a half and full turn. Apparently that helps lean out the top RPM range without affecting the lower range as much.

The other breakthrough was going through the setup of my long/short rods and the throttle idle/wot stop screws. I know there are people who will say I should set them with the factory tool and then NEVER touch them. But I'm running bigger cams, higher compression pistons, programable ignition curve and a HP Spica pump, so it seems like experimenting with the linkage to find the best settings that work for my motor isn't crazy.

With the factory settings it was getting to max on the Spica input a little before the intake plates were fully open.

I did experiments with the extreme edge cases - longest possible short rod vs shortest short rod, setting the stop screws for fully closed and evenly open for each combination. What I realized was that the shorter the short rod was, the sooner it would reach its fully open position relative to how soon the long rod would get the Spica throttle input to reach its maximum.

For me, the best setting seems to be shifting things down with a shorter short rod. It does have the angle on the bell crank a little shallower than the factory tool would dictate, and from the way I understand the geometry of the linkages works out I'm getting more air in the intake sooner relative to the fuel input.

And indeed, my partial throttle and cruise numbers were much leaner. To compensate the FCS is now turned out by about half a turn from where it was to get those numbers back down - and now I'm also leaner (and stronger) at WOT.
 

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71 Berlina 74 GTV 17 Giulia Q4
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Nice work! What AFR are you shooting for at max rpm? I noticed my pump would lean out significantly above 6200 to mid to high13's. Sounds like we have similar motors. 12mm intake, 11mm ex, ported head, bla, bla, bla.
 

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I run a similar setup on my Alfetta ChumpCar. Ported head, 10:1, 11.5 cams, but a standard points type dizzy. We spent some money at the local dyno shop and found results similar to yours. Best power was made as near to 12.5 as possible at WOT, 5 degrees BTDC with a factory advance curve. We restrict ourselves to 6k RPM so no testing was done above that. Since a race car (unlike a street car) has a digital throttle, AFR at other throttle positions is pretty well irrelevant to us.

As with you our adjustments were carried out mainly with the baro compensator, but factory setting for the rods.

Prior to our testing we had experienced ring land failure due to detonation even though we were using 100 octane race gas. No further problems after fuel delivery was straightened out (surprise!).
 

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71 Berlina 74 GTV 17 Giulia Q4
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Schazam! Son of a gun! I also had two separate instances of ring land failure with motronic pistons due to detonation/fuel delivery. It was occuring at max torque not at high revs. After a hellva lot of blow by I finally got the fuel delivery sorted out. To be honest I was paying to much attention to what was happening at high revs and not at max torque.
 

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It's interesting to compare your graph to the curves in the AFR weber tuning thread.
Much of the data in the Weber thread is from my motor. This SPICA motor maintains a tighter control of AFR at WOT in the full power range. My target was 12 - 13 and not higher than 13.5 anywhere at WOT. From the dyno curves, I did not lose torque until the AFR dropped below 11 so running a little fat is fine as long as you are not trying to get better fuel consumption.

There is one thing about Mike's experience that I don't understand. Your detonation was at around peak torque but your fuel delivery problems were at higher rpm. Do you have a theory as to why that was the case?
 

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71 Berlina 74 GTV 17 Giulia Q4
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That is rather confusing. The top end situation was with webs and 130 mains. I noticed that above 6200 it leaned out to around 13.5, granted I don't drive it there much but that and the high 12's at wot on the way to 6200 convinced me to put the 135's back in.
The fuel delivery problems were with the HP pump at max torque, 4000 rpm, 5th, 410 rear end. There was a noticable vibration that only showed up there after the motor had warmed up. I was getting different answers from the same person as to afr and finally came to the conclusion after many consultations with several folks that trying to detect detonation with a afr is unreliable at best.
Sorry for the confusion, heck I confused myself talking about two different things.
 

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When I was playing around with the AFR I concluded that main jets mainly affected the lower and middle part of main circuit and had little effect on the top end unless they were too small and in that case it went lean everywhere. So I would drop down on air correctors and maybe put the 130 mains back.

Apologies for hijacking this SPICA thread.
 

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Discussion Starter #16 (Edited)
What AFR are you shooting for at max rpm?
Initially I was hoping to get into the low 13's, but after doing some more reading and experiments with what my motor really does I'm happy with it in the 12's across as much of the range as possible. Dipping into the 11s in the low RPMs doesn't seem that bad.

Here is a WOT run through the first four gears. I stopped at about 85mph in fourth more because of running out of the strip of road rather than anything that was happening with the car, it was still happily accelerating. Its feeling like it pulls really strong - and I like how flat and even the third gear pull is (the blue line is 12.6).

KR_AFR_ACCEL_141109a.jpg

I've gotten some good information from Jeff Hartman's books, particularly How To Tune And Modify Engine Management Systems. None of it is about Alfas, and certainly not 40 year old mechanical Spica fuel injection systems - but there is still good stuff about tuning for power and economy that seems applicable.

Here are the targets that he lists:

11.5 AFR - Best Rich Torque at Wide Open Throttle
12.2 AFR - Safe Best Power at Wide Open Throttle
13.3 AFR - Lean Best Torque
14.6 AFR - Stoichiometric AFR (Stoich)
15.5 AFR - Lean Cruise
16.5 AFR - Usual Best Economy


The way my pump is dialed in right now seems like a good compromise. It pulls strong at WOT, if maybe a little rich in the lower RPM ranges but gets to the mid 12's for most of the power range. On the freeway at cruise its in the 14-15.5 range with momentary spikes into the low 16s. Partial throttle and moderate acceleration is in the 13's and feels good.
 

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71 Berlina 74 GTV 17 Giulia Q4
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Super info and very well presented, something there for everyone.
 

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Yes. Neat information. Thanks.

I added a wide band AFR gauge to my autocross Spider. It seemed to be very sensitive, and I used the information when talking with Wes after he did his latest upgrade to my HP pump. But, right at the end of the season, the gauge broke - or locked up - or something, and doesn't respond other than +/-.1 from idling to driving at WOT. The car is put away for the winter, so I have time to explore if the trouble is the oxygen sensor or the gauge itself. Then, back to the chassis dyno in the spring.

Regarding the previous posts, Wes also warned me to monitor WOT AFR at max torque as well as max RPM.

Super info and very well presented, something there for everyone.
 

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I agree, excellent data that is well presented. I have one question - what is the file format for the charts? I created Excel files for my Weber AFR data and they were too big to upload and I had to take pictures of the computer monitor.
 

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Discussion Starter #20 (Edited)
I really like the logging feature in the LM-2. The software they provide for the PC is called Logworks and its available to download from their site:
Support :: Innovate Motorsports

The hand held LM-2 unit has several display modes while its running, and you can put an SD card in it to log the data. When you copy the files to the PC they are in a .d32 format. I find that once I modify stuff the software wants to save them as .log files. Looking at both in a text/hex editor the format is not obvious (its not just xml, csv or other direct encoding). But the files are very small (driving around for an hour or so is only a few hundred KB) and the software has some nice features for selecting, overlaying, marking and such.

For the pictures I've posted here, I've just been simply doing screen captures of the graphs from the application.

Here is the product info on the LM-2 itself. I've been very happy with it.
LM-2 Wideband O2 Digital Air/fuel Ratio Meter


Right now I have the RPM data from an inductive clamp on the distributor wire and the AFR comes from the O2 sensor, but it also supports a couple analog inputs and I'm working on getting a throttle position sensor hooked up as my next project. After that maybe manifold air pressure and possibly even hooking up and adjusting the vacuum advance feature on the 123Ignition. Pretty amazing stuff for a 40 year old car in my garage at home...
 
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