Leaderboard

Yes, that is the correct spec for 1971. Not sure your issue is the same thing I've dealt with, but I've had issues with the floats in the past. I'm sure you've seen some of this? I started getting involved at around page 8: https://www.classiczcars.com/forums/topic/55190-float-level-advice-please/?page=8

I have rebuilt a booster. It takes some special tools which I had to build. I still haven't tried it to see if it works properly. If I were doing it again, I would have Harmon do it for just a few dollars more... https://harmonclassicbrakes.com/

Not finding needle valves readily available was probably a good thing. I probably would have ordered them, however, I went out to the garage and took the float cover off again and inspected everything again. This time I used about 10 psi of compressed air and checked to sealing. The float was turning quite a bit angled in order to get it to seal. That doesn't make sense to me. I don't get why the floats aren't more level at the point where the needle seals against the seat. In this case, the bottom edge of the float appeared to be crossing over where the side of the float bowl would be (if the cover was on the bowl). Perhaps the side of the float was interfering with the side of the float bowl and not able to rise more to seal the needle against the seat. Though I used the clear tube method to set float levels previously, I repeated that process tonight with this carburetor bowl, and again set the float level so gas came up to a mark I set at 20 mm from the bottom edge of the float cover. Is 20 mm from the bottom of the lid is correct? The needle and seat is working properly again now. I took the car for a another brief 3/4 mile drive. It was not fully warmed up, but it ran a bit better than before at 2.5 turns out on the mixture screws. Assuming I don't run into another issue, I will get it up to temp and try another brief road test tomorrow to see if I will be able to get the mixture close by backing out the mixture nuts a bit more. Perhaps I will need to switch to different needles. I don't know.

grannyknot's build car sold. Pretty good money but I thought it would get more. https://bringatrailer.com/listing/1972-datsun-240z-342/

I seem to remember oversize pistons being hard to find a year or two ago. Looks like the supply has been rebuilt. Good news for engine rebuilders.

Took another look at the carburetors tonight. Neither piston was dropping to a "clunk" in the carb bodies. The needles were touching the nozzles, and that was keeping the pistons from going to their correct locations when doing the "piston drop" test. I was wondering why my idle speed kept moving around! I loosened the nut holding jet bridge and centered it properly on the rear carburetor. Firing it up briefly, the idle is MUCH improved. I will do the same for the front carb and give it another little test drive.