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1972 Float Adjustment ...

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If you look around this forum, (it may have even been in this thread or posted by those I am replying to) the method I found for setting the proper float levels was...

1) Adjust your fuel nozzles all the way to the top, so the top of the nozzle is flush with the bushing in the carb housing. (If its not maybe there are pieces missing in the stackup of hardware, not sure.)

2) From there back the nozzles down a full 10 turns of the fuel adjustment. Its quite far. 

3) At this point you want the fuel level when the bowls are full to be at the exact top of the nozzles in their lowered position. If you shine a flashlight you can see the fluid kind of "doming" as it reaches the top but hasn't spilled over.  (I found it easier to actually go like 9-9.5 turns and have the fluid lower in the nozzle. Then as it turned it to 10 turns watched to see if the fluid changed or spilled over the top as I passed 10 turns.)

4) Once you have this fuel level set correctly your floats are done. You raise the nozzles up all the way to the top, and then back them down the 2.5 turns which is your "starting point" for tuning.  From there you can adjust to get maximum airflow and maximum RPM (richness/lean-ness)

I'm far from a carb expert, I'm only 34... but this is what my research on this exact forum showed as the most foolproof way to set the float levels especially given my inconsistent results with the Float to Bowl Lid gap method that Ztherapy's DVD calls for.

I could be totally off on all this, but my car runs pretty well and tuned as expected so I don't think I am way off base.

Edited by DaveR
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39 minutes ago, DaveR said:

If you look around this forum, (it may have even been in this thread or posted by those I am replying to) the method I found for setting the proper float levels was...

1) Adjust your fuel nozzles all the way to the top, so the top of the nozzle is flush with the bushing in the carb housing. (If its not maybe there are pieces missing in the stackup of hardware, not sure.)

2) From there back the nozzles down a full 10 turns of the fuel adjustment. Its quite far. 

3) At this point you want the fuel level when the bowls are full to be at the exact top of the nozzles in their lowered position. If you shine a flashlight you can see the fluid kind of "doming" as it reaches the top but hasn't spilled over.  (I found it easier to actually go like 9-9.5 turns and have the fluid lower in the nozzle. Then as it turned it to 10 turns watched to see if the fluid changed or spilled over the top as I passed 10 turns.)

4) Once you have this fuel level set correctly your floats are done. You raise the nozzles up all the way to the top, and then back them down the 2.5 turns which is your "starting point" for tuning.  From there you can adjust to get maximum airflow and maximum RPM (richness/lean-ness)

I'm far from a carb expert, I'm only 34... but this is what my research on this exact forum showed as the most foolproof way to set the float levels especially given my inconsistent results with the Float to Bowl Lid gap method that Ztherapy's DVD calls for.

I could be totally off on all this, but my car runs pretty well and tuned as expected so I don't think I am way off base.

Maybe i should try it later on when i become an expert. At the meantime ill keep up with Mark´s advice.

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1 hour ago, DaveR said:

For what its worth, with Ztherapy's new grose jets...

Not wishing to hijack this thread, but is there a new Grose Jet? They went NLA awhile back — just curious.

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The attached image is the method often called for to set it initially, including what ZTherapy's DVD shows. This is what did not work AT ALL for me, because the grose jets that Ztherapy sent me no longer can support the weight of the float and made the adjustment very different from what the original intention was. If you use original jets with stronger springs then you can probably still use the original method. 

----
For the Z therapy jets....technically what this image is illustrating is that at this height of the float, you want the grose jet to close and the fuel to shut off.  I tried to simulate this by running a hose to the inlet port and pressurizing it by blowing in to. As I moved down the float I noted when the grose jet closed, and at THAT point in the travel, the gap from the lid to the float should be the 9/16"

In actuality this didn't work and my levels were way off. So I did it the more cumbersome way by replacing the lid and float assembly each time I needed to adjust the tangs.
----

I even called Ztherapy to ask about this and was basically told that the adjustment method used in the video wasn't valid any more with the style of grose jets they use now. (I can't swear this applies to anyone else besides me, but that's what they said to me) I attached a picture of my float assembly which shows it being very droopy because the spring that forces the grose jet open wasn't strong enough to hold up the additional float weight so it just compressed. I had to bend my float bracket to such an extreme level to get the measurement that it didn't look right. If I recall correctly it made my fuel level way too low.

 

GaP.png

IMG_20160722_242116093.jpg

 

 

As for the grose jet... I don't know if the Nissan one went NLA... I used the Ztherapy ones.  

Edited by DaveR
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6 minutes ago, DaveR said:

The attached image is the method often called for to set it initially, including what ZTherapy's DVD shows. This is what did not work AT ALL for me, because the grose jets that Ztherapy sent me no longer can support the weight of the float and made the adjustment very different from what the original intention was. If you use original jets with stronger springs then you can probably still use the original method. 

----
For the Z therapy jets....technically what this image is illustrating is that at this height of the float, you want the grose jet to close and the fuel to shut off.  I tried to simulate this by running a hose to the inlet port and pressurizing it by blowing in to. As I moved down the float I noted when the grose jet closed, and at THAT point in the travel, the gap from the lid to the float should be the 9/16"

In actuality this didn't work and my levels were way off. So I did it the more cumbersome way by replacing the lid and float assembly each time I needed to adjust the tangs.
----

I even called Ztherapy to ask about this and was basically told that the adjustment method used in the video wasn't valid any more with the style of grose jets they use now. (I can't swear this applies to anyone else besides me, but that's what they said to me) I attached a picture of my float assembly which shows it being very droopy because the spring that forces the grose jet open wasn't strong enough to hold up the additional float weight so it just compressed. I had to bend my float bracket to such an extreme level to get the measurement that it didn't look right. If I recall correctly it made my fuel level way too low.

 

GaP.png

IMG_20160722_242116093.jpg

 

 

As for the grose jet... I don't know if the Nissan one went NLA... I used the Ztherapy ones.  

Well i tried to set mine to .55 inch barely touching the tip of the needle valve and its still lean. Ill guess ill need to bend the tang more.

20180220_192326.jpg

20180220_192259.jpg

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To de-clutter this thread a tad, the up-to-the-minute info from Z Therapy is that they have not offered Grose Jets in years. What's being discussed here is the older vs the current replacement version of the standard SU needle valve . The new one comes from a different source and is a little different in design. This photo compares the current version on the left to the OEM valve. Reference to Grose Jets in the ZTherapy video is outdated and should be treated as such. The Grose Jet is an entirely different critter.

suvalves.jpg

Edited by NVZEE
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I wonder why they won't put a piece of paper in with their rebuild kit explaining that? I set mine the way the dvd shows and my car ran like $^!# for a year until someone mentioned it in a post. 

 

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Until this moment nobody has come with a precise response regarding from where to where is the .55 inch, 9/16  or 14mm measured? Is the measurement taken with the tang barely touching the neddle pin or with its weight on.  I measure it with the tang barely touching the needle pin and the mixture at 2.5 turns clockwise is still lean. Please see my post #156 for pictures as reference. Am i still to lean? Should i lower it?

Edited by jalexquijano

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On 2/13/2018 at 3:29 PM, jalexquijano said:

Thats what i meant the measurement of the 0.55 inch gap is taken with the bracket just on top of the pin and not depressing it. You need to be clear. The dvd is not clear and asidea from that it refers to grose jets and not needle valve.

20180213_175036.jpg

And believe me I do apologize for this problem we seem to carry forward showing the lid/float turned upside down like this. This was shown by the original owner of ZTherapy using Grose Jets which we haven't been able to get for about 14 years. Can I get the video fixed to reflect how to do it with needles and seats? Not so far.....With needles and seats with the tiny spring inside, the weight of the float will over power the spring and your float level will be tits right out of the chute. Turn the damn thing over blow lightly into the fuel inlet tube while moving the float toward the lid. When the needle closes you should feel resistance to your breath. That's where your measurement should take place. Bend the tang on the float to get that gap from the top of the float to the bottom of the lid. Once you get both set the same, put your hands in your pockets and back away.

THEN: You start tuning the carbs. First thing is THAT 2 1/2 TURN THING is ONLY a starting point. Steve sets our "out the door REMANS" at 2 1/2. Most any motor (or engine for you sticklers) will start at 2 1/2 turns down but almost assuredly will end up up or down from there BASED ON THE MOTOR. Set the mixture and balance and go use your butt dyno to make 'er run. Keep tweaking til it runs.

I do have to ask: who's lid is this in the photo? Don't even tell me the caps are left on the overflows for running.

I'm going to my room......

 

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  Bruce beat me to it. Thanks Bruce.

Let's try this. It may be an easy way to support the floats while checking the height. Remove the gasket from the float cover. You'll be using the lid surface for your float measurement reference point. Cut two strips of something flat (plastic, card stock, shim stock, etc,into strips about 3" long. One strip will be 9/16" wide, and the other 5/8" wide. With the float lid inverted, insert the 9/16" strip under the unsupported end of the float, resting on the lid gasket surface and blow thru the fuel inlet fitting.  The 9/16" strip, then the 5/8" strip. Adjust the float tangs until there is air flow past the needle and seat using the 5/8" strip but no air flow using the 9/16" strip. Hopefully the 5/8" and the 9/16" strips will act like a go, no go feeler gauge. This method should work for getting them close. We'll check the fuel level in the nozzles, when you get it reassembled, to be sure they're correct.

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4 hours ago, DaveR said:

2) From there back the nozzles down a full 10 turns of the fuel adjustment. Its quite far.

That's what I thought I remembered from a few years back. Not 2 1/2 turns down. Didn't want to post about it since I wasn't sure and haven't tried that method. I don't know where the fuel level in the bowls will end up. I know there's a Nissan tech. bulletin about float bowl fuel levels but I can't find my digital copy. IIRC it's 22 mm down from inside of lid to fuel level for the rear and 25 mm down for the front, please verify this. Page EF-25 of the '72 FSM says it's 23 mm down (for both carbs) ; the tech bulletin corrects this for the later carbs with different front and rear fuel levels. Hope someone posts that bulletin again or has a link to the original posting. Since there's no way to measure from underside of the lid to fuel level we need to use micrometer to measure from underside of lid to top of the bowl, which is easy to measure to.

Using the "same level of fuel in the nozzles" method will get the fuel lever difference between front and rear bowls correct if the car is on a level pavement, but it won't necessarily get the absolute level from the lid correct unless the "10 turns down" has been adjusted to work with revised fuel levels in the tech bulletin.

Maybe 2 1/2 turns down is correct for the nozzle method, but if you're wrong fuel level will be way too high and run out the carb and lid vents, so be ready to switch your engine off fast if it does. If you have the sightglasses, it might be better to use that for a ballpark setting, and then use the nozzle method to get them perfect. Since the nozzle method gets the front/rear difference correct, you only need to check the rear carb to verify correct fuel height. Mark's post a minute ago would also be OK for ballpark.

Edited by Stanley

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Thanks for joining in, Bruce. Adding this to the thread gives everyone a fresh reference on how to approach a persistent issue. You should come out of your room more often 😉

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 Someone correct me if I'm wrong. I'm assuming the 10 turn down method is viewed with the float cover removed and the 2 1/2 turn down method is with the floats installed. More assumption now, that would mean the installing the lids (floats) would raise the fuel level in the bowls about 7 1/2 turns. is this a correct assumption or am I missing something?

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40 minutes ago, Bruce Palmer said:

And believe me I do apologize for this problem we seem to carry forward showing the lid/float turned upside down like this. This was shown by the original owner of ZTherapy using Grose Jets which we haven't been able to get for about 14 years. Can I get the video fixed to reflect how to do it with needles and seats? Not so far.....With needles and seats with the tiny spring inside, the weight of the float will over power the spring and your float level will be tits right out of the chute. Turn the damn thing over blow lightly into the fuel inlet tube while moving the float toward the lid. When the needle closes you should feel resistance to your breath. That's where your measurement should take place. Bend the tang on the float to get that gap from the top of the float to the bottom of the lid. Once you get both set the same, put your hands in your pockets and back away.

THEN: You start tuning the carbs. First thing is THAT 2 1/2 TURN THING is ONLY a starting point. Steve sets our "out the door REMANS" at 2 1/2. Most any motor (or engine for you sticklers) will start at 2 1/2 turns down but almost assuredly will end up up or down from there BASED ON THE MOTOR. Set the mixture and balance and go use your butt dyno to make 'er run. Keep tweaking til it runs.

I do have to ask: who's lid is this in the photo? Don't even tell me the caps are left on the overflows for running.

I'm going to my room......

 

Print that and make a copy to go with each rebuild kit.  You would save everybody that buys the kit a lot of headache with those instructions.

"Put your hands in your pockets and walk away" that's classic and should be the last sentence on every set of instructions. LOL

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37 minutes ago, Mark Maras said:

 Someone correct me if I'm wrong. I'm assuming the 10 turn down method is viewed with the float cover removed and the 2 1/2 turn down method is with the floats installed. More assumption now, that would mean the installing the lids (floats) would raise the fuel level in the bowls about 7 1/2 turns. is this a correct assumption or am I missing something?

I think they're saying the extra 7.5 turns down is that 1/16th you are talking about at 2.5 turns down? 

This simple thing people have done since they came off the boat has gotten knee deep on this thread and he has 3 active now. I think it'd be easier to raise the plane ticket money and send Mark down there and have boots/wrenches on the ground. LOL

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Found it, posted couple years ago. I was wrong it's 4 mm difference not 3. Still not clear how this relates to the 23 mm down from the underside of the lid measurement. Fig. EF-47 in the FSM shows a dimension "H" = 14 to 15 mm, that's almost but not exactly like the measurement of 11.5 to 12.5 mm rear, and 15.5 to 16.5 mm front in the tech bulletin. Fig. EF-47 shows the dimension from the underside of the lid to the tang on the float, while the picture in the bulletin shows it from the lid to the outer surface of the float. No big deal I guess.

0.55 inch = 14 mm     15.5 mm = 0.61 inch      11.5 mm = 0.45 inch
So maybe make the plastic 0.61 for the front and 0.45 for the rear.

TechnicalSupportBulletin-TS73-10.PDF

I still think that method's iffy. Too dependent on fuel pressure and the action of the valve. Maybe the new valves with the skinny pins react different. BTW, the pins in the new valves are kind of wobbly and will stick open if the tang on the float isn't flat enough. Too much curve in the tang is bad. Maybe it's possible to substitute the pin with an old type pin, with the other parts new. Haven't tried, might not work.

Edited by Stanley
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3 hours ago, jalexquijano said:

Until this moment nobody has come with a precise response regarding from where to where is the .55 inch, 9/16  or 14mm measured? Is the measurement taken with the tang barely touching the neddle pin or with its weight on.  I measure it with the tang barely touching the needle pin and the mixture at 2.5 turns clockwise is still lean. Please see my post #156 for pictures as reference. Am i still to lean? Should i lower it?

There are solutions posted that don't require anything but an initial ballpark for the float position. This is what I had to do. I would suggest not even bothering with a measurement, and instead install it, fill the bowls and see how high they are. Then adjust the float up or down and repeat. This is the only way I could get mine properly set, and I well understood why my original measurements weren't working.

Bite the bullet and forget about the 14mm etc. I stand by the 10 turns approach and set as I detailed above. This didn't originate from me, but it did work well for me. 

Edited by DaveR
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2 hours ago, Mark Maras said:

 Someone correct me if I'm wrong. I'm assuming the 10 turn down method is viewed with the float cover removed and the 2 1/2 turn down method is with the floats installed. More assumption now, that would mean the installing the lids (floats) would raise the fuel level in the bowls about 7 1/2 turns. is this a correct assumption or am I missing something?

Fuel adjustment all the way up. 

Turn it down 10 turns with everything assembled except the domes and pistons. 

Let the fuel pump fill up the bowls without the car starting.

Check the fuel levels relation to the top of the nozzle by eye shining a flashlight in.

If it's above the top of the nozzle, remove the float lid, bend the Tang in correspondence with raising or lowering the fuel level, suck out some fuel so it's back below the nozzle top.

Reinstall float bowl top.

Run the fuel pump again. Check. Repeat until done. You want the fuel level right at the top of the nozzle hole and right on the verge of flooding the top on the nozzle which is now 10 turns down into the bushing. You want the fuel to remain down inside the nozzle but right the the top.

I unplug the dizzy and use my starter motor and battery to cycle the fuel pump and check what it fills to.

After you are happy with the level... Reassemble everything. Undo all 10 turns so the fuel adjustment is at the top. Then go down 2.5 turns and use that as starting fuel level for tuning.

Edited by DaveR
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2 hours ago, siteunseen said:

Turn the damn thing over blow lightly into the fuel inlet tube while moving the float toward the lid. When the needle closes you should feel resistance to your breath. That's where your measurement should take place. Bend the tang on the float to get that gap from the top of the float to the bottom of the lid. Once you get both set the same, put your hands in your pockets and back away.

For what it's worth I tried this before my above method and it wasn't as accurate as I liked... But it was better than a blind guess. I still prefer the check and adjust with the nozzle 10 turns down

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22 minutes ago, DaveR said:

For what it's worth I tried this before my above method and it wasn't as accurate as I liked... But it was better than a blind guess. I still prefer the check and adjust with the nozzle 10 turns down

Front and rear fuel levels after adjusting tang.

20180223_190816.jpg

20180223_191737.jpg

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I see you hooked up the sightglasses. Just bend the plastic hose and hold it vertical right against the side of the float bowl. Get a pencil and draw a horizontal line on the float bowl that lines up with the fuel level. Then do the same with the other carb. Get your micrometer and measure the millimeters from the bottom of the lid (or the top of the bowl plus the gasket) and write it down. Then check the other one and write it down. It should be about 25 mm down for the front one and 21 mm down from the lid for the rear.

If it's close then you're ready to fine-tune it with the "nozzle" method. If it's Within 1 mm it's close enough since the fuel level goes up and down that much when the engine is running, as the float valve opens and closes. If you watch the sightglasses carefully with the engine running you can see that happening. Use the nozzle method for the last stage since it's the most accurate. Also with the nozzle method you don't need to think about the fuel in the front bowl being lower than the rear. They should both be the same level in the nozzles.

If you check it 10 down in the nozzle and they're both very close to right, then you're done. Don't get carried away getting it perfect. You can get almost perfect, adjust the tang very slightly, and just make it worse. In fact the process can be described as "make it better, make it worse, make it better, call it good". Just make sure you "call it good" after making it better, not after making it worse.

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14 hours ago, Stanley said:

Found it, posted couple years ago. I was wrong it's 4 mm difference not 3. Still not clear how this relates to the 23 mm down from the underside of the lid measurement. Fig. EF-47 in the FSM shows a dimension "H" = 14 to 15 mm, that's almost but not exactly like the measurement of 11.5 to 12.5 mm rear, and 15.5 to 16.5 mm front in the tech bulletin. Fig. EF-47 shows the dimension from the underside of the lid to the tang on the float, while the picture in the bulletin shows it from the lid to the outer surface of the float. No big deal I guess.

0.55 inch = 14 mm     15.5 mm = 0.61 inch      11.5 mm = 0.45 inch
So maybe make the plastic 0.61 for the front and 0.45 for the rear.

TechnicalSupportBulletin-TS73-10.PDF

I still think that method's iffy. Too dependent on fuel pressure and the action of the valve. Maybe the new valves with the skinny pins react different. BTW, the pins in the new valves are kind of wobbly and will stick open if the tang on the float isn't flat enough. Too much curve in the tang is bad. Maybe it's possible to substitute the pin with an old type pin, with the other parts new. Haven't tried, might not work.

Just noticed that the fuel  pressure even with the new pump is 3 psi when the former one when installed Brand new measured 4.2 psi. Something must  be limiting the fuel pressure even though you argue that 3 psi is enough. Another thing i have noticed is that the engine does crank at 2.5 turns clockwise but  will not hold it for many seconds if i dont open them to 3 turns clockwise on both. I thought that if the engine does not keep up to 2.5 turns without the choke on, something is wrong.  

Edited by jalexquijano

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