Well, I just got my colortune in the mail and it confirms exactly what I already knew. I am rich, even with the adjustment knob all the way up on the front carb. Oh, this is on 3 screw 72 round tops

Last night I checked the valve lash while hot and only had to adjust a couple of valves from the cold setting. The float seems to be set right at 23 mm from the bottom of the lid. I also synced them at 1500 and 700 rpm.

This evening I tried tuning with the gunson and got the rear carb right where I want it. Even the lift the pin method is showing good on it.

The front carb is another story. Even though it is rich I can only get it to run good at 1.5 - 2 turns out. I can't get the color to hit blue no matter how tight i get the screw. However, fully tightened the car will barely get out of its own way and will lean pop. At eithet setting opening the throttle will net a blue flame and a quick opening will flash yellow.

Does this mean my needle/nozzle is toast? Would it make more since to fiddle with my floats again and lower the level a mm or so?

Edited September 7, 201014 yr by hogie

Try tuning them at the same time.

There is a balance tube for this reason, so make 'em both rich and then progressively lean them out together...at the same time. Don't finish with one and go to the next one...as you know, that doesn't work well.

Good luck mate.

I dont think I have ran into any guides saying to adjust them at the same time, but it is worth a shot.

Again, make sure that choke cable on the front carb is relaxed in the off position. Any time I see this "I can't adjust it out" that would be the first place I'd look. Either that or you have a grossly worn needle and nozzle or the float is high enough as to allow gas to pool up on top of the nozzle. You can check that by removing the dome and pistoon and look down at the top of the nozzle for pooled gas. You can also do the needle nozzle wear exam then too.

I will check both tonight and let you know how it goes.

I had to watch the little man last night so I didnt really get much done. However, I do know the choke mechanism was fully released as the nozzle was all the way up.

Would running 17 degrees advance change the way the car responds to the fuel mix? I am not getting any pinging under acceleration. And it wont run well at lower levels of advance.

Here is a great write up if you have not read it:

http://datsunzgarage.com/engine/index.htm

That where I found the method I used to find my float level. I will try to make sure the level matches the nozzle sometime tonight.

You are aware that on the 1972 cars the float heights are different. On a '72 you set the rear carb float height to 12mm and the front to 16mm. This is per Nissan TS73-10 dated February 9, 1973.

http://www.classiczcars.com/forums/showpost.php?p=255145&postcount=3

I was aware, but then forgot....so I guess the fuel level should be at the 19mm on the front? That seems way low, though I guess it wouldnt really be a one to one ratio in level change.

I have new valves, but haven't had much luck with setting them to the level specified against the float valve/lid.

16mm (not 19) on the front, which is just 2 more mm then the 70/71. Or looking at it from another perspective, two full turns on the mixture knob.

Sorry, I meant that as what the actual fuel level would be in the bowl as opposed to the float to lid setting?

Well I got the front float set to 16mm today and it does seem to run a little bit better. I am not sure what this equates to as far as level inside the float bowl, but it was a significant change from the last setting I had used.

It is still a bit hard to start after driving it for awhile. I just have to press the gas just a bit to get the engine to catch.

Both carbs now idle up slightly and then drop in revs after lifting the pins slightly so I am at least in the ball park. Too bad the colortune still shows rich.