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Discussion Starter #22
We will be in Fort Collins from May 23 to June 4. How is your schedule?
 

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Discussion Starter #24
I played around with idle jets some more trying to go leaner. I thought that I was making progress until I found that 3 of the 4 cold start valves were leaking. The brass clips that hold the return springs had popped out. It has happened before. They now have a small amount of JB Weld on them to hopefully secure them. I had been running 55F8 and 55F11 but I am now back to 55F9.
 

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Discussion Starter #25
Bling

I visited Richard in Pensacola this weekend and he suggested that I take the Autocomponenti valve cover that was on Hayes Flynn's motor when it blew up. We called Jim and he gave the transaction his blessing. It must be worth at least another couple of HP :smile2:
 

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Discussion Starter #26 (Edited)
AFR curves

I sorted out the noise problems with the Zeitronix ZT2 and I did a couple of 3rd gear WOT runs today. They were on my old test strip up a 3% grade. The conditions were overcast, 70F, 30.1" pressure, 81% RH.
The purpose of the runs was to compare F!6 emulsion tubes, first old ones - presumably made by Weber and then new ones from the Czech Republic.
They were quite similar with the Czech tubes producing slightly less rich dip at 4700 rpm. Main jets are 150 and AC's are 190.

The third log is from November 2016 with the old motor - same exhaust system, same carbs but with 140 MJ and 170 AC, same intake cam but timed a little differently and similar exhaust cam timed the same. Different head, intake and pistons.
The time from 3500 to 6500 was 9.6 seconds with the old motor and 8.1 seconds with the new one and the old run was with cooler air and less humidity.

The bigger main jets which are needed for correct AFR at peak power are making a lower rich dip at 4700 with the new motor.
 

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I visited Richard in Pensacola this weekend and he suggested that I take the Autocomponenti valve cover that was on Hayes Flynn's motor when it blew up. We called Jim and he gave the transaction his blessing. It must be worth at least another couple of HP :smile2:
I see I'm not the only one that uses that spark plug wire marking protocol. Must be a "nuke" thing.....(grin)
 

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Discussion Starter #28
Yes. You only need to mark 2 & 3 as you would find it difficult to mix 1 & 4.
 

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Discussion Starter #29
Modified emulsion tubes

I drilled an extra pair of holes in the Czech F16's and did a WOT run today. The temp, pressure and RH were similar to yesterday. The effect is to flatten out the AFR curve and I am pleased with that. The holes are 1 mm and they are 3.3 mm below the land that lines up with the bottom of the air corrector.
 

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Now showing at a theater near you:

The Carb Whisperer
Starring Ed Prytherch

Nice work my friend!
 

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Discussion Starter #31
The question now is should I stick or twist?
I may transfer the AFR/rpm data to an Excel file so that I can make a better analysis of what I have done and maybe make another change. On the other hand it is pretty darn good for 45DCOE's any any more improvement is likely to be minor. It is the engineer vs the driver.
 

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The question now is should I stick or twist?
I may transfer the AFR/rpm data to an Excel file so that I can make a better analysis of what I have done and maybe make another change. On the other hand it is pretty darn good for 45DCOE's any any more improvement is likely to be minor. It is the engineer vs the driver.
I would wager you cant stop. I continue to push the envelope in everything I do. I surely admire and appreciate the work you do with your Alfa. I wish I had access to a dyno around here but I am not sure if there even is one in my backwoods county.... Got one for motorcycles at the local shop that I have made use of but the guy that operates it treats it more like a novelty than a tool....
 

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Discussion Starter #33
You can learn a lot without a dyno if you can find a nice test road and buy a data logging AFR meter, such as a Zeitronix ZT2.
 

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There is certainly no shortage of "test roads" in my neck of the woods! But living in CA limits any mods significantly....
 

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Discussion Starter #35
I can't help you with that problem. You have a great climate and a beautiful state, you got to give up something.
 

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So true. Tonight comes a wind storm, same kind that burned two towns to the ground last year. PG&E is turning off the power to 800,000 customers due to fire danger because of 55 mph winds and single digit humidity....
 

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Discussion Starter #37 (Edited)
Emulsion tubes

I drilled two more 1.0 mm holes in the new F16 tubes so there are now 4 holes at 3.3 mm from the top land and I did back to back WOT runs with the modified tubes and then stock F16 tubes. The significant change is centered around 4000 rpm where the extra holes have shifted the AFR from about 11.7 to 12.2.

The next step is either to fill in these 4 holes and drill 4 new ones a little lower down or leave them and just add 4 more. I need to think about this one.
 

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Discussion Starter #39
Here is my analysis. The 1 mm holes at 3.3 mm from the top have raised the AFR between 3200 rpm and 4600 rpm with the biggest difference at 3900 - 4000 rpm. So 1 mm is influencing a spread of 1400 rpm. I want to raise the center of influence to 4700 rpm, an 800 rpm shift so I should move the holes 800/1400 mm down which puts them at 3.9 mm.
 

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Discussion Starter #40
second modification

I soldered up the first set of 1 mm holes and I drilled another set at 3.9 from the top land - .5 mm lower than the first set. I manually read the data points from the Zeitronix logger and loaded them into Excel in order the make a clear comparison. My conclusion is that drilling the holes in the F16 tubes has not had much effect on the depth of the AFR dip at 4700 but it has raised the AFR on either side of the dip. The holes at 3.4 mm have had more effect below 4700 and the holes at 3.9 mm have had more effect above 4700 rpm.
 

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