Duffman

I don't have logging software to graph my results, unfortunately, but I did the same thing you did with consistent runs from 3000 to 5500 rpm on a flat road. I was getting solid readings on my gauge. Sent from my iPhone using Classic Zcar Club mobile

Phoenix, AZ, is about 1100 to 1200 ft above sea level.

I have finally got my triples dialed in on my 70 Z with rebuilt L28, stock cam and flat top pistons. Thanks, Blodi, for posting your experience, it helped me a lot! And a big thanks to 240260280 and Chickenman for all of their help over the last number of months, it helped make sense of these wonderful carbs! Weber DCOE 40 151 current specs: Venturis - 32 mm, auxiliary - 4.5 mm, float needle valve - 1.75 mm, idle jets - 50F9, main jets - 161 (drilled), air corrector jets - 200, pump jet - 50, pump exhaust - 00, emulsion tube - F16 I am running around 12.5 to 13.5 on acceleration, with 14.5 on highway cruise (with AFR gauge). Idles very smooth at 850, but could go lower if I wasn't running AC. Life is good ...

Oh, I had flat top pistons installed when engine rebuilt 10 years ago, so getting about 10 to 1 compression, if that makes any difference.

I have an N42 head/N42 bottom end engine that I added triple Webers to this last year. I am enjoying them immensely. I wanted to port match and unshroud the valves to get best air flow and enhance performance. I believe the N42 head is a good option for headwork, but am wondering if the FI notches on the intake ports will cause any issues on port matching? I wanted input from those of you that know about this much more than I! I appreciate your thoughts. Stephen

Original flattops?

Thanks, Blodi, makes sense.

How are you doing a repetitive test run to compare results on an apples vs apples basis?

I found out my AEM AFR meter (#30-4110) has the analog output capability for data logging, look forward to see how my numbers look in graph format! So much tweaking, so much fun!!

Thanks for the info, might have to look into getting one!

Gentlemen, stupid question, how are you putting these graphs together? Are you attaching something to your AFM? I don't know if you are just taking readings and putting the graphs together, or creating them directly from AFM. I want to create my own. Love the thread!

Thanks, Zup, will reach out to S30Driver and see what he did to resolve this issue!

I just acquired a set of Rota Shakotan 15x7 wheels. The center caps are not deep enough to leave room for the dust cap on the front wheels. Any ideas on finding a deep enough (1 1/2" clearance) cap that will fit in a 62 mm wheel opening? Thanks!

TechFlex F6 Woven Wrap 3/4" 10' Wiring Split Wire Covering F6W0.75BK https://www.amazon.com/dp/B00C1OOTDM/ref=cm_sw_r_cp_apip_vzFqjsjqiKik9 Sent from my iPhone using Classic Zcar Club mobile

Stanley, the split wrap is what I use, got it on Amazon. Great stuff! Sent from my iPhone using Classic Zcar Club mobile

Update, bought the fuel level tool Blue mentioned from Japan. Have all 3 carbs at 29 mm down, so now know for sure I have correct, uniform fuel levels! Put new washers in with the pump jets, but still getting fuel dripping on all 3 carb air horn bolts underneath. Fuel pressure has been dialed back to 2 to 2.25 psi, no difference. Car runs good, still need some jet adjustment per Chickenman and Blue, but close. Any more thoughts? Sent from my iPhone using Classic Zcar Club mobile

240260280, I am not measuring the fuel level from the lid, per your inference. I am measuring the float level, per instructions, 14 mm down from the lid and gasket. This is supposed to equate to an appropriate fuel level. The key, I believe, is Blue is stating the fuel should be 6 mm below the aux venturi opening in the side wall of the emulsion tube, or 6.5 mm to the center of the fuel level. I am measuring the fuel level from the top incorrectly. so I will focus on the distance below the aux venturi opening.

I guess i am stumped then, Blue. I measured 14 mm down from the lid with gasket to the top of the float and all carbs have the same fuel location at 16 mm down. If I try to get to 29 mm down to the center of the fuel level, I am not sure I can bend the float tang enough to make that happen. Love the measuring tool, by the way, would be great to have!

Thanks, Blue, again great stuff! I agree, will try to best tune what I have and then change the chokes and emulsion tubes if necessary. I am comfortable that I have followed your list of "other" aspects that need to be in place to best tune my triples, Sorry, I was struggling with the 29 and 29.5 mm down the emulsion tube opening, my fuel level is 16 mm down from the top of the emulsion tube opening threads. So, I called Stephen at Pierce Manifolds (he is very helpful) and asked him where the fuel level should be in the emulsion tube or, more importantly, what I should visually see down the tube. He told me that the fuel should be 3 mm below the lower edge of the fuel opening on the side wall. Based upon what I was seeing and after remeasuring the float level, this made sense. So, I was more than 3 mm and I adjusted the float level accordingly, This made a difference on my trial runs, providing smoother transitions from low to high end. I love that DatsunZGarage article, have it saved. Keep in mind, he has a cam upgrade, whereas mine does not. Stephen

Chickenman, your time and thoughts are greatly appreciated! I realize that tuning triples is like putting together a massive puzzle, but with patience and input from people in the know, like yourself and Blue, it helps move towards an appropriate solution! My stock L28 engine was rebuilt about 8-10 years ago (10,000 mi on it), still shows 190 compressions across all 6 cylinders, have ZX distributor for electronic ignition, recurved distributor (needs no vacuum advance) and 6 to 1 coated headers, So, nothing too souped up, just a good running, stock Z! Appreciate your thoughts on specs, will look at incremental changes and see if the results steer me towards your suggestions! Blue, I apologize for taking over this wonderful post, don't want to take anything away from it!

Blue, disregard, was able to confirm the level of fuel I needed. Was told 3 mm below opening in side of tube wall by Pierce Manifold, that seems to make sense and I am still too low based on that description.

Still confused as to why it is running lean on acceleration, if I have so much fuel in bowl! Weird ...

Measured my float, per instructions, at 14 mm down from lid. Measured the level of fuel in aux venturi tunnel, and it is only 16.25 mm down. Can't believe it would be off so much! All 3 carbs measure the same. I used the zip tie approach, marked it at 29.5 mm and stuck it down the tube. I measured from the top, where the tube actually screws in, not the top of the carb lid.

Good stuff, Blue! My carbs are the 151 version of 40 DCOEs, on a stock, rebuilt L28. For clarification, dripping is not out the air horns, but underneath the horns, can feel some fuel on the bolts underneath the carbs that secure the air horns to carb. Have doubled up the mini crimp washers on the pump jet and, along with tightening them down further, this has stopped the dripping out of most of the barrels. Venturis seem to be seated correctly, will double check. Choke cables are not connected, don't need them in AZ! Appreciate your comments on the idle jet size (will play with that) and how to measure the correct fuel level, Will report back with results. Thanks, Duffman

Thanks, Blue, I have much to learn. My 40's are dripping off the pump jet in a number of the chambers, part due to the pump jet cover not being screwed down tight enough, but I need to confirm the fuel level to make sure this is not contributing to the problem. I am getting fuel dripping off the front of my air horns, in some cases. Also, goes very lean on hard acceleration, then richens as the main jets kick in. My specs: triple 40 DCOE carbs, 30 mm venturis, auxiliary 4.5, idle jets 50F9, main jet 125, air corrector 175, pump jet 45, pump exhaust valve 050, emulsion tube F11, float needle valve 1.75. Idles like a champ at 750, hard acceleration runs 15.5 to 16.5 on AFM, flutters and farts on deceleration (super lean), typical transition miss from idle to mains. Once I confirm (and correct, if needed) fuel level, will look at pump jet size and acceleeration pump performance to see if I am missing something there. Will try some of your ideas once I get the fuel level confirmed! Open to any other ideas or thoughts!