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Try drilling out the F11's and give it a go. Your fuel ~ 29mm should be ok.

I don't think fuel level or stock ETubes will make a difference as F2, F9, F16 were all tried and no big change in the dip.It is always there. Likewise Leon runs 25mm fuel depth and you run ~29mm and the dip is there. The only parameters not changed yet are the Aux Venturi and eTube modifications.

Nice to see good friends!

Done... I bought the CD. My content is free too. I still hate the way ads and the new Visually Impaired Giant Text For Phones wrecks websites. The tools listed above barely make the web usable.

You weren't drinking this suff? btw there is a Bee in Beer.

Aren't our hoods supposed to come in through the glass and cut off our heads?

https://www.ghostery.com/ https://www.ublock.org/ https://adblockplus.org/ You can use ublock to kill annoying space hogging crap on web pages too. Before After

I wish there were, then we could tease them about their wooden floor boards ?

What are ad's?

That interior!

What we learned: 1. It was hoped the rich dip at the start of the Main Circuit was due to the Accelerator Circuit's squirt but you proved it to be not the case: 2. Etubes were tried but the rich dip at the start of the Main Circuit remained: 3. Other Datsun engines of different sizes with 45DCOE's experienced the same rich dip at the start of the run Maybe enlarging holes near the mid-to-top of an Etube is needed to lean the start greatly? The F11 tubes look like an easy candidate for drilling. They have 4 0.1mm holes that are horizontal. It looks like you can drill straight through the body to enlarge two of these 4 holes at a time. If you are keen, you can consider the following: 1. Put F11 in and appropriate main and air to get a few baseline runs. 2. Cross drill on one axis to enlarge two of the 4X100 holes 3. Conduct a few measurement runs. 4. Analyze results. 5. Drill out more or solder as needed.

I did some checks and one Weber book has this: The 42DCOE Throat is "over-carbed" so a 3.5 is used. They also use the 3.5 on a 3 X45DCOE on a 3.8litre Jag so they go smaller Aux with larger Carb. But Passini states: " A small-bore nozzle is, on the whole, better from the economy aspect and, unless the pulse energy transmitted to the well at high revs is so weak as to demand a very rich setting that can spoil the lower range, it is better to try a small one first. Engines with fairly large cylinders and siamesed inlet ports normally prefer larger auxiliary venturis." His comments about being lean at high end and rich at the low end with smaller Aux Venturis seems to be the problem with the 45DCOE's and 4.5Aux. @Chickenman What are your thoughts on how to flatten the strange WOT A/F shape of 45DCOE's on Z's? Is the Aux Venturi a significant player?

I thought about this for an hour before falling asleep. It is troublesome. This same shape seems to be independent of E-tubes, choke size, jet size, fuel level (as I believe Leon runs 25mm and you are running ~29mm) and engine size. It happens on the 2.55litre Equivalent A15 and on >3.0litre Strokers! There has to be another parameter no one has addressed.. So I remembered something from Passini ... the Aux Venturi. I'll do more research and if it is a lead then I'll buy a set and ship to you.

The more one looks, the more one finds ? Here is fuel rail on HLS30-00249 in that area. Throttle shaft looks the same but the bracket is closer to the middle of the engine: HLS30-00013 looks the same as #249

Thanks for the high resolution! Here is another find. The inlet on the fuel pump is on the front and outlet is inboard. Also the exit hose the pump is light colour. I'll dig some more ? HLS30-00013 Fuel Routing.

Thanks! They all have the wonky shape. Even the Stroker with 38mm chokes! Super rich dip 3k to 4k then leaning on the top end. DCOE 45'S - (End of day settings at dyno shop - 38mm Choke | 145 MAIN | 160 AIR | 65F9 IDLE | F11 )

Possibly but it does not happen on 40's. Can you re-post the link above in post #305?

The A15 has 32mm chokes. You tested 34mm, 35mm and 36mm with the same shape of wot run so it seems independent of nearly every parameter. Hopefully higher fuel level will help.

No need to rush. They did not discuss the a/f on the site. It was a race site so I am surprised to see this wide range of leaner excursions to 14.

For information: Here is a WOT dyno run for a Datsun 4 Cylinder with A15 engine and dual 45DCOE with 32mm chokes. A/F ratio shape from start to 6000 seems similar to yours but with 4.5 point spread.

Good Eyes! Almost. Here is the original I used above c/o Kats: https://www.classiczcars.com/forums/topic/22141-my-clollection/?tab=comments#comment-323796 This is also the same car in the Maintenance Manual that Kats posted. You can see the light coloured fuel hose in this photo c/o Kats Here is another from Kats with better clarity. The fuels hoses are very light and the dist. cap is green. The strange 3rd hose from the fuel rail is there.

A comment on using only water. The pressure exerted by the water in the hose pushing down on the fuel needle to open it is 33% more than gasoline (assuming density of gas is 750kg/m^3) The pressure exerted by the fuel float pushing up to close the fuel needle valve is ~ 33% more in water than in gasoline. So using water is not very inaccurate as the two forces nearly cancel each other. The key point in using water is to use the table above to get ~3.4psi of head.

Good point. I recall a coolant hardline that wrapped around the back of the head for running coolant through later manifolds but did it terminate so high up where the fuel rail is and was it on early models?

Water Column Height (Head) to PSI at sea level. 240z pump output pressure is 3.4PSI so use ~7' 11" for Weber bowls or stock SU bowls. If you use an electric pump and external pressure regulator, dial the regulator to 3.5psi and use 8' If you use gas in the hose rather than water, multiply the psi in the table below by 0.75. You will need ~10.5' of gas head to get 3.4psi.

Hi Kats, Another mystery ? I re-coloured one of the red photos from the service manual. I hope you enjoy it. In doing so, I noticed two unusual features that did not make it to production. 1. The fuel rail to carb hoses are very light in colour (not black). 2. There seem to be three of these hoses coming from the rail rather than just two. ( 1 to the front fuel bowl, 1 to the rear fuel bowl, 1 that seems to go to the fuel bowl area [see second picture]) Any idea on what material the hoses are made and the purpose of the third hose?