1 hour ago, dutchzcarguy said:

It needs to be just a little stripe of paint that indicates if a screw has come loose after some time..

No. It indicated that the fastener had been torqued to spec on assembly and checked. Nothing after that.

Yes, and you do this after you torqued that particular bolt.. not all at once on a sunny afternoon when you feel like painting them all at once haha..

But.. if you make a stripe, you can ALSO see what moved! 😉

1 minute ago, dutchzcarguy said:

But.. if you make a stripe, you can ALSO see what moved! 

But that's not what is being discussed here. The yellow marks were applied on the production line to show that a check had been performed, that's all. Nobody was checking them for movement anywhere after that. 

Tell-tale markings - as used on race cars, for example - are a different thing. Usually thin stripes or dot points on adjacent components that can be quickly checked by eye. Like this:

 

The yellow marks from the factory were applied pretty sloppy, like inline6 did. Here is a good reference of an original car, check out the under pictures

 

https://bringatrailer.com/listing/1971-datsun-240z-124/

Right, my understanding is that the yellow paint marks were applied at the factory to indicated the fastener had been torqued.  If you have a look at the paint markings on the 240z that sold on BringaTrailer for $310,000 US a few years ago, starting at about picture number 168, you will see that the paint was applied quite messily:  
https://bringatrailer.com/listing/1971-datsun-240z-124/
 

And, for what it is worth, I personally torqued all of these fasteners to spec! 

Edited February 19Feb 19 by inline6

This past weekend, I moved all of my project cars around to facilitate getting started on the "track car" - my 240Z with a prod date of 12/70:

      

 

    

I blew the motor up at Road Atlanta 9 years ago.  It took many of those years to get a replacement, but I have that sitting in the corner of the shop. 

While I had the project cars out of the "shop", I organized some things and put a bunch of parts away in boxes and on shelves.  Then I put them back in the garage.  My order of attack will be to bring this 240Z back to life, then repair my wrecked 2004 Honda S2000, and then build the 1970 510.  Unsure how long it will take, but going to guess 6 months or so on the Z.  Hopefully less than a year on the S2000.  And, I really don't know how long for the 510:

Probably several years.

But I still have some things to finish up with this restoration.  I removed my wide band O2 sensor from the track car yesterday and will be installing that in the newly restored 240Z soon to see what I have going on for air/fuel ratios. I'll be able to record some data with this and the wide band O2:

 

 

I got the LM-2 hooked up today and made one run to log some air fuel ratios. The situation right now is basically

• idle: around 10.5

• cruising at around 70 mph is about 16.5 to 16.8

• giving it a decent amount of throttle to accelerate: above 17

Of note, I have the front carb fuel level set by the "wet set" method and the back carb set by using a 14-15 mm length of a nail and blowing on the inlet (air will not flow with the specified length nail between the roof of the float chamber cover and the float).

Since it is rich at idle, I am going to redo the front carburetor float level to match how I set the rear one. I am hopeful that will lower the level in the front carb and consequently, lean out the ratio a bit at idle. Assuming I do get that result, I will then unscrew the mixture screws equal amounts to attempt to get lower AFR's at cruising and under throttle. If I recall correctly, they have been unscrewed exactly 2.5 turns as they sit now.

My rpms signal is not recording well. I need to try a couple of things in the LM-2 manual to see if I can get that registering correctly.

Edited Sunday at 01:08 AM3 days by inline6

I'm no carb expert, but I don't think a small change in float level is going to have much of an effect on the numbers.

Are you sure your dampers are damping? What oil are you running in the dampers? Maybe try something thicker?

15 hours ago, Captain Obvious said:

I'm no carb expert, but I don't think a small change in float level is going to have much of an effect on the numbers

I don't think so either, but am hoping :)

I am using SAE 20 - this one, actually:
https://www.acehardware.com/departments/automotive-rv-and-marine/fluids-and-lubrication/lubricants/10705

I carefully put it in and the level is registering on the high line of he SU "dip sticks".

Since the engine is not stock, I am thinking the stock needles may not work properly. The engine is over-bored and has .030" cast pistons, and it has an E31 head. It has this Isky cam: Grind No L-475

• Stage 1

• Intake 26-64

• Exhaust 64-26

• V. Lift 0.475

• V. Lash Cold 0.006/0.008

• Advertised Duration 270

• 0.050 Duration 222

Intake valves are 44 mm SI stainless, exhaust are SI stainless in the stock size
The exhaust system is not stock - I am using a Zstory header and exhaust pipes.

The carburetors have been completely rebuilt (by Paltech, who I don't think is in business anymore). They are in sync/balanced. And, I have confirmed timing and correct distributor advance functionality.

Now, I am off to change the float level...

Well first two things I would do would be to A) pull the needles to see what number they are, and B) try a thicker weight oil.

Paltech probably reused the original N-27 needles, or put in SM needles (because that's what many other people do). Pull em to see what you have? I'm not normally a fan of the SM's but with the number's your seeing, it might be just the thing. The SM's run leaner at idle and richer towards the top.

And for the oil, I've gone up as far as 20W-50 in one cer I've messed with. In theory, it won't do anything for steady state, but should help for hard acceleration and throttle blips.

And if you get totally convinced it's a needle problem and can't find something stock the fits the bill, let me know.

I've cut a few custom needles.

Thanks. If I recall correctly, the needles don't have any markings on them. Originally, I believe they had N-27 "silkscreened" on the portion that slips inside the piston, as were some replacements I was able to source new from a dealer in the 1990's.

Adjusting the float level on the front carb to match the rear carb, my idle AFR went from around 10.5-10.8 to 11.0 to 11.3.

I will proceed with something more than 2.5 turns on the mixture screws as an experiment to see how much is required to get more desirable AFRs during acceleration with load and steady state cruise. Anticipating that idle will be unacceptably rich when I attempt this. If so, I will likely look at other needle options.

Edited yesterday at 01:44 AM1 day by inline6