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Great. No need to rush! Good luck with the dyno tests.

I had deposits on my 77 EFI on plugs 3&4. It was due to cracks in head. The exhaust ports on 3&4 are the only two adjacent exhaust ports and heat builds there. Maybe exhaust valve lash is too tight on 3 & 4allowing reversion. Here is 3&4 exhibiting darker colour on cracked head (EFI):

F19 165/175 Range of 1.7 points. Note: this is close (but better) than the elusive June 28, 2017 plot that suddenly went too rich on subsequent runs. It was never repeated. The configuration then was (F16 165/215).... so the F19 runs leaner than the F16 and needs a smaller air corrector.

What you mean?

Two coats on the dining room and Janet is happy! The only thing left to play with is to mess with the acceleration circuit as you see fit. You can try to quench that common lean gasp at the start. You know the parts and what they do so I'll leave it to you now that you are a Weber Experten! ?

You know this thread started Oct 2016... two years of work, down time for the head problems, so many runs and Etube changes and we finally seem to have nailed the 45DCOE on larger L engines. Perseverance and finally a gift to the Z folks out there! F19 eTubes are the cat's meow! ?? Cheers and a big thanks for your hard work! YIPEEE YAAAAHOOOO

WOW THAT LOOKS SWEET 11.5 to 13.5... RIGHT where it should be. 13.0 +/- 0.5 for most of the run then dropping to 12.5 at the high end.... WOW WOW WOW. I am painting inside right now. I'll try to plot tomorrow. Hold there. it looks great!

If the tube is too rich ~ 3000-4000 then reducing main will lean across whole band. Reducing air should enrich across the whole band but less at 5000- 7000. Just trying to figure out how to deal with your findings. Lets wait to see a plot.

Smaller mains and smaller air will help. Sounds like a significant change! Great! Now to tame it ?

A racer in our club jumped on it. Sorry it is gone ?

Will do. It is buried in my garage. I've had it since ~ 2006.

Stroker Crank $1000

Sadly Janet and I have to bow out ? New job and we just bought 5 acres in the country for a new home so it is a busy time.

You could also lower the air corrector. It does seem strange for the large jump as the tube design seems to promote more air than fuel.

Vapour blasting peens the surface and slows some oxidation effects.

One member had a valve seat drop out of the head. This caused the loose lash pad.

Wow that is significant. Don't go too high in rpms if it starts to lean out.

An optimistic spin would be: the craters hold more oil ? You helped me with a problem with Delta ground cam and rockers that ate each other on Dr 240z's 240z

I never saw yellow zinc on a jan 71.

Great. This one is worth waiting for! It should hopefully shed light on the elusive E tube workings.

With a second look it seems the "intake" is a re-purposed 2 into 1 exhaust collector.... there may be a backwards turbo out of the shot.

That black valve cover made me look twice. S20-ish! Nice!!!

unique intake piping

Use a 165 main to be safe. That will give a ball park. If a/f starts to go over 14 then stop run and go bigger on main. Good luck! Fingers crossed this will change the shape!!

The advice on this forum will save you even much more when you start turning wrenches.