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  Topic Review (Newest First)
Today 06:51 PM
I thought Alfas were nimble?
It was on a narrow winding road with trees close to the road on both sides. Low light and driving briskly through tight turns and I barely saw it before I felt the bump.

I am not trying to make anything richer. My understanding is that holes make things leaner and high holes effect the low end and low holes affect the high end. I drilled holes 3.3 mm from the top and the weakening was centered at 3900. My rich dip is at 4700 so I relocated the holes a little lower. I filled the first set with solder and drilled a new set. I have a pin chuck that will grip very small drills and it is gripped in the chuck of my drill motor. Like this: Precise 3 Piece Pin Chuck Set - 3700-0501 - Penn Tool Co., Inc
Today 04:54 PM
gigem75 I thought Alfas were nimble?
I take it you are trying to lean out a specific rpm range? And are you using a dremmel to drill the holes? Maybe I'm getting something wrong but seeings how the F16 just has the holes around the bottom wouldn't the upper rpm range be richer? Which is what I'm trying to do. No braking and or emulsification of the fuel?
Today 12:14 PM
alfaparticle I modified my F16 tubes again - soldered up the holes that I had drilled and drilled a new set a little lower down. On the way to the test track I drove over some tree debris that took out my fuel pump. So it will be a few days before I can do the tests.
Today 06:46 AM
gigem75 Good information Ed, Thanks and I'm sure others do to. My mid range and low AFRs are good. It would really be good if I could log my data like you do and have a curve to look at but that would the only reason I have to get a laptop.
What I'm trying to do is get the AFRs down into the 12s and 13s at peak rpm in the upper gears. Everything else is good. It seemed better with the F16s but like I said it was a wet road and hard to keep any eye on both the road and the AFRs.
I have 200 ACs now and will order some smaller ones.

edit, I don't get it. I've talked with Innovate tech support a couple of times and I've or at least I thought I'd been told I needed a laptop to log data. I went to their site because I was thinking about getting a cheap used laptop so I could log. Lo and behold they have the pocket logger that writes to an SD card! No laptop required. It's also reasonably priced!
Yesterday 11:40 AM
alfaparticle Mike,
Here is my take on emulsion tubes.
F9, F11 and F15 are identical except for the number and location of high holes. The diameter of the tubes and the orientation of the low holes is the same. So if you have data from an F11 then you should able to estimate the effect of changing to an F9 or an F15. The extra holes that I drilled in my F16's are 3.3 mm from the top land and their effect seems to centered on 3900 rpm so that may be a data point for estimating which rpm ranges are being influenced by the holes in the F9 series. Higher holes lean the mixture at lower rpm.

F16's are different. They are larger diameter and the single row of low holes are at 90 degrees to the axis of the tube. The low holes in the F9 series are angled up. I don't understand the effect of that. Pat Braden tried to explain it in his Weber book but he was confused about which holes were angled and which were straight so I am not inclined to follow his explanation.

So I would look carefully at the drawings for the F11 series and compare the positioning of the holes with your AFR curve and decide where you would like to tune it. Just about every AFR curve that I have seen for a Nord motor has a rich dip at about 4700 and I will try to find the location of holes that correspond to that rpm. I expect that the location will be similar between F16 and F11. If you switch to F16 you will probably have to change main jets and/or air correctors to get your AFR correct at peak power rpm - most likely around 6200 with your motor. If the air correctors end up being 200 or more then you may be able to go down 5 on the main jet and about 30 on the AC to get the same AFR at 6200 but leaner at lower rpm. The size of the rich dip at 4700 seems to be bigger with larger main jets so finding the smallest main jet/AC combo should minimize the dip. After that you may want to start messing with emulsion tubes but I would definitely optimize MJ/AC first.
My other observation is that air horns exaggerate the rich dip to the degree that you may see a significant corresponding dip in the torque curve.

I will update this thread after my next emulsion tube tests
Yesterday 10:10 AM
gigem75 The F16s look promising. It's misting with light rain and all the oil has come up out of the pavement which makes it exciting. The tires break loose in 3rd when the torque hits and 4th is pretty fast on wet pavement but the AFRs appear to be lower at the upper revs but I was only looking with one eye with the other on the road.
Gordon got my cores Friday so I'll have a great oil pump soon.
Yesterday 08:27 AM
gigem75 I don't have a way to record except to video the AFRs with an electronic tach in the frame. I do have a set of F16s in addition to the F15s. The F16 has fewer holes and only at the low end which should make it richer than the 15s. I'll try the 16s.
Yesterday 07:59 AM

The other "factory" E-Tube used in Alfas was the F9. It has 2 more holes 3mm lower than the 2 Ed drilled in the F-16. As well it has 4 holes in the larger diameter area below the ones mentioned above.

I'm considering making a test set by soldering up the 4 holes in the
F-9`s middle area and and using the same main & AC jets to use while I have both cars at the Atlanta race in November.

I know the likely cause is reversion in the 4200-5000 rpm dip, but its worth a try.
Since I shortened the airhorns if just that improves the AFRs I`ll remove the 1" portions and see if that doesn`t help as well. With the large airboxes maybe the reversed Fuel/Air mix will be better dissipated.....

Addition.. Ed`s post was at the same time as mine. Maybe I will just drill 2 holes as Ed did originally on a set of F-16s.
Yesterday 07:59 AM
F16 tubes

I drilled two more 1.0 mm holes in my new F16 tubes at the same height as the first two and I did back to back WOT runs today. The AFR's at 4000 rpm are 12.4 for the modified tubes and 11.7 for the stock ones so the height that I selected for the holes corresponds to 4000. The next step is either to fill in the new holes and drill another set a bit lower or leave them and drill extra holes lower down. I think that the modified tubes run a bit leaner at part throttle but that is subjective.
Yesterday 07:53 AM
alfaparticle Can you post pictures of the AFR/RPM curves?
Yesterday 07:28 AM
gigem75 Since I ran current straight from the battery via a relay to the AFR and it has cooled off considerably my
AFR readings are different. Great everywhere except in 3rd and 4th @WOT. Beginning around 4500 the readings go lean into the high 13s and low 14s. Everywhere else is fine.
I have
50f8 idle
F11 tubes
200 AC
135 mains
34 venturies
I have checked the fuel pressure and it's 4 psi behind the carbs, the gauge was at the inlet of the second carb. Flow is good but I don't know an exact number.

What I have here now are 140 mains, F15 tubes, and 55f8 idle jets. No gottie 195 AC
As I understand it the F15 tube is richer than the F11 and the only one richer than the F11. I'm more than happy to be corrected on that.
Any suggestions on what to try first, main jet or tube? I plan on ordering more ACs = 195 and 190
10-08-2019 10:25 AM
gigem75 For the what it's worth department. I called the techs at Innovate because it seems like the heater light stayed on to long. He recommended pulling the + straight off the battery and trigger with a relay. What I didn't understand is the wires are like 30ga and don't seem like they could handle a lot of current but when I did what they said the sensor heats up faster and the readings seem to be more accurate. I don't know if the 12v is any cleaner but I suppose it could be.
10-08-2019 08:55 AM
alfaparticle See post #29 of for effect of extra holes in F16 emulsion tubes.
09-11-2019 05:42 PM
alfaparticle Yes, it cleaned it up and therefore I should not need to swap ZT2's.

Not sure what did the trick, changing component values or running a good ground from the bar on the rear of the cam cover to the ground point for the ZT2, or a bit of both.
09-11-2019 03:54 PM
65Sprint Ed, did the new interface clean up the tach signal compared to what you had? We can still swap ZT-2s sometime.
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