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Glad you are sorted. Yes that run looks nice but as you say 0.5 point leaner will be nicer.

Great solution! Another way to skin the cat would be to cut a reverse thread into the other end to make a turnbuckle-like adjustable solution and forego the welding.

I can put you in touch with a bilingual Z nut who keeps after me to sell #249. He even gave me this mega photo he took of it before it came my way. He looked at it but did not know how special it was and missed the opportunity. Seems like an OK guy.

Verify age http://www.cbc.ca/news/canada/montreal/used-car-lien-nightmare-1.4295456

Datsun Music: https://www.youtube.com/watch?v=wUVQBC-0GOo What I used in video(Japanese Singer) https://www.youtube.com/watch?v=WZZzxS_SGHY

This thread should be of interest. http://www.classiczcars.com/topic/41332-understanding-a-weber-side-draft-carburetor-through-a-fictional-supposition/ What size chokes are in your carbs?

Fuel height is an important parameter affecting the slow the off-idle transition to the mains as well as the fuel richness when cruising on the highway. 30mm down to 27mm down are optimal for Webers. It is a critical tuning parameter. It is important to balance the fuel height with a friendly sized idle jet to get the best performance for the off-idle transition and the air/fuel ratio at cruise. The number of turns on the idle enrichment screw are not important and come after finding the best idle jet and fuel level. here is a nice blurb on fuel height: http://www.classiczcars.com/topic/44512-setting-weber-dcoe-fuel-level-with-caliper/

What 40DCOE version do you have? The later 150/151's have finer thread and the turn out at idle is usually ~ 2 turns.

All is right and good in the world again!

Murphy's law. Glad the e-tubes arrived. We will have great data soon! No need to rush... snow is still far away

Great. Thanks for reporting the details, it helps to rule out variables. No worries about the free-air calibration. It should be close. Still it is difficult to understand the cause of these occasional strange jumps in behaviour. Why the recent run has the rise in the middle part of the run is baffling. The larger air jet should have leaned the top end like the 238 but not as much. Maybe it is atmospherics as SweatyBetty suggested. I guess more testing is needed. It sure is iterative. Hopefully the new E tubes on the way will have different shapes with no hump in the middle. We could be simply battling an"F16"... and not the type that flies.

btw are all tests run with air filters either in place or removed? A partially restrictive air filter will have a choke effect and draw more fuel so if they are in place for one run but not for another, a change in AF may occur,

Very strange. The middle hump raised. No flattening occurred, Try the 165 to add more fuel. Maybe a free-air recalibration is needed too.

Very strange. I wonder if we are battling manufacturing variance? Weber used to flow test every jet before stamping with values based on flow measured (not drill bit size). I doubt modern suppliers of jets do this or even change or measure their drill bits often enough.

Good! Something just does not seem right with such a defined transition.

Gone to a world of cheapies who use phones as internet portals..... to hell with computer screens. Next they will put small screens on guns or rip down the cinema big screens and put a cell phone in every chair next to the biggie gulp cola and extra fake buttery pop corn.... what a screwed up world.

They hit the suck button. Slower, less content, more scrolling, more crap. The internet continues to get worse.

Chris, I am sorry to see your loss. I am glad your are tracing (pun) the problem. For the photo below: 1,2,3 do look very lean, or they were simply not receiving the lubrication oil on the walls that burned naturally in 4,5,6 to colour them? Did you trace the oil passages to confirm the slipped shim could have put less oil in the from half of the motor vs the rear half and cause the burn pattern we see on the cylinder domes?

I checked specs and all 280zx distributors gives 17 degrees of mechanical advance. If you put 20 degrees of initial advance in then you are 37 total so it would be in the ball park. Too much advance under load at higher rpms will reduce power and may ping.

Yes, 20 at idle is most likely too high. It depends on what distributor you have. You need to buy a timing light (preferably one with advance) to measure your timing at different rpms. The max timing you want is ~ 36 to 38 at 3000 rpm or above.

plate should be as closed as possible. At first progression hole or closed even more is best.

Check this thread http://www.classiczcars.com/topic/56375-weber-selection-and-initial-jet-tuning/

There is a current thread on tuning DCOE's on L28. It may be helpful. Do you have 40's or 45's? Please measure your fuel height in all 3 carbs and make sure your linkage is synchronized.

I have digital crayon Actually it is just done by selecting a region then using a "colourize" feature to tint it. I use Paint-Shop Pro Version 5 from Windows 95 days. Works great for what I need.