1972 Float Adjustment ...

[Mark Maras]

 The typical symptom of a leaking needle valve is over filling the float chamber. A little leakage will influence the performance, a lot of leakage and fuel would be running out of the over flow tubes and or the carb throats. Needle valves are pretty resilient. I don't think that you have a bad one but since you're in doubt and have new ones, put the new ones in.  The easiest method of checking the fuel level in the float chamber to see if a needle valve is leaking is by pulling the domes and pistons. The float level in the float chamber is the same as the fuel level in the nozzles. If the needle valve is leaking, the fuel level will probably be over the nozzle top.

 

[Johnny wick]

I am dumping the rest of the kit. I just bought it for the needle and seats which i hope are of good quality.

Anyway the car is still too lean at 3 turns clockwise. Engine starts responding better at 3.5 turns each carb. However i did noticed that if leave it warming up for more than 20 minutes number 4 spark plug starts to foul and causes a misfire when reving. I have cleaned all plugs and will test again.

[JLPurcell]

25 minutes ago, jalexquijano said:

I am dumping the rest of the kit. I just bought it for the needle and seats which i hope are of good quality.

Anyway the car is still too lean at 3 turns clockwise. Engine starts responding better at 3.5 turns each carb. However i did noticed that if leave it warming up for more than 20 minutes number 4 spark plug starts to foul and causes a misfire when reving. I have cleaned all plugs and will test again.

I tuned my carbs the normal way, but the addition of the "color tune" plug gave me a way to confirm the tune by being able to see the combustion color. Blue with a slight yellow pattern is preferred for performance according to the color tune guide. 

[Johnny wick]

Managed to clear up but at 4 turns clockwise.  Shouldnt this happen at 2.75 to 3 turns clockwise? 

Edited March 6, 2018 by jalexquijano

[Mark Maras]

 It's possible the floats are a bit low.

[Johnny wick]

what do you mean by low? it is set as post # 213. You mean lower than the 9/16 or .55 inch by bending the tang a Little more? smaller gap??

Edited March 6, 2018 by jalexquijano

[Mark Maras]

 Low is just a guess. take a look at the fuel height in the nozzles. That will tell you which way the fuel level needs to go.

[Johnny wick]

My reasoning is that if i have to turn the mixture knobs 4 turns clockwise when it was supposed to be 2.5 - 3 turns clockwise, the tang needs to be pushed a little bit more and the gap will be less than .55 inches.

[Mark Maras]

 That's correct.

[240260280]

SU's work fine with the top of the fuel at 23mm down from the inside roof of the fuel bowl.

This translates to ~20mm down from the margin where the lid rests on the fuel bowl

 

[David F]

1 hour ago, 240260280 said:

SU's work fine with the top of the fuel at 23mm down from the inside roof of the fuel bowl.

This translates to ~20mm down from the margin where the lid rests on the fuel bowl

 

Maybe, maybe not.  For me, not so much.  Worked fine and was spot on for the front carburetor (long valve), but was way off for rear carb (short valve).  The fuel level in the rear carb had to be set significantly higher on my engine for proper tuning.  Hard to say what has changed with the carbs over the years that make one method work or not work.  For instance the fuel bowl indexing bushing could be wrong for the position (front or rear carb) which could affect how fuel level in the bowl correlates to the level at the nozzle.  In the end, the fuel level at the nozzle is the only thing that matters so why not check the level where it matters and forget the other dubious methods.

Edited March 6, 2018 by David F

[Mark Maras]

 IMO there's too many variables associated with the float chamber to assume that a measurement is going to get a float level dead on correct. David summed it up. "In the end, the fuel level at the nozzle (2 1/2 turns) is the only thing that matters so why not check the level where it matters and forget the other dubious (grey area) methods."

 I'm going to repeat the caution used when adjusting choke cables. Be sure when the choke lever is off, both nozzles are all the way up. 1 mm difference in nozzle height (caused by an "it's close enough" choke cable adjustment) is the same as 1 full turn of a mixture adjustment screw.