Checking correct fuel level at Round Top 3 screw SU CARBS Float bowls

[jalexquijano]

19 hours ago, Stanley said:

Yes, use the long valve in the front bowl and put the float back in the original holes like Nissan intended. The fuel level needs to be lower in the front bowl and that makes it easy. What happened with the ztherapy plastic sightglasses in the first post ? That's what I use. Or the ones by Randalla. Or use the "both nozzles at same height, same fuel level in the nozzle" method. If you can use either of those methods why bother measuring .55 inch or whatever ? That method is a little iffy, even if it's in the FSM.

Make sure the car's sitting level, not on a sloping  driveway while setting the floats.

What if i decide and fasten the long needle valve on the front float lid and move upper to the original ear holes and then fasten the pair of tubes to the drain holes on both carbs? How high should the fuel be in both carbs?

[Mark Maras]

 It sounds like you're taking it back to original design. I believe that you're shooting for 23 mm in the front bowl and 21 mm in the rear. Someone, anyone, correct me if I'm wrong. Opinions vary on these measurements. Most seem to like the 21 mm in the rear and if the difference in pivot point height is 2 mm, 23 mm in the front would be a good starting point. BUT you'll never truly know if the floats are correct until you pull the domes, pistons and look at the fuel level in the nozzles, 2 1/2 turns down. Then and only then will you know for sure if they're right. 

[jalexquijano]

any pictures so i can guide myself after removing both drain plugs and installing the sight clear plastic tubes i bought from ztherapy in order to set the correct level on both carbs? i hope i can dial both su carbs at 2.5 turns clockwise equally.

[jalexquijano]

On ‎05‎/‎15‎/‎2017 at 7:50 PM, Randalla said:

Bruce and Z Therapy don't have them. I'm the manufacturer and sell them on Ebay for $69.95. I had the same issue as many others so I designed this product. The nice thing about them is that you can check fuel levels with the running or not

Are you still selling this float synch tool? I have tried setting the 23mm with the hoses and clips i purchased from Bruce but its becoming a complete nightmare and i want to move further with this float adjustment.

[jalexquijano]

On ‎02‎/‎18‎/‎2018 at 7:32 PM, Mark Maras said:

 It sounds like you're taking it back to original design. I believe that you're shooting for 23 mm in the front bowl and 21 mm in the rear. Someone, anyone, correct me if I'm wrong. Opinions vary on these measurements. Most seem to like the 21 mm in the rear and if the difference in pivot point height is 2 mm, 23 mm in the front would be a good starting point. BUT you'll never truly know if the floats are correct until you pull the domes, pistons and look at the fuel level in the nozzles, 2 1/2 turns down. Then and only then will you know for sure if they're right. 

Can you explain the 10 turns method more precisely? Should i warm the car for 2 minutes and then proceed with the 10 turns clockwise or should i just open both float lids and measure the fuel height with caliper stick?

[Mark Maras]

1 hour ago, jalexquijano said:

Can you explain the 10 turns method more precisely? Should i warm the car for 2 minutes and then proceed with the 10 turns clockwise or should i just open both float lids and measure the fuel height with caliper stick?

 No need to run the car for two minutes. In reality you just need to fill the float bowls to the new setting. if you're lowering the float setting be sure to remove some fuel from the bowls so they can refill to the new level. If you haven't readjusted the floats just pull the lids and measure with a caliper and readjust. 

 I've not used the 10 turns down previously but here's my understanding of the 10 turns vs the 2 1/2 turns. 10 turns down should be an accurate method of setting the fuel height. My assumption is when the floats are reinstalled they displace the fuel raising the level to 2 1/2 turns down. Now for the big IF. If all floats displace the same amount of fuel, the fuel level will rise to 2 1/2 turns down in all float chambers. I doubt if all floats are equal, especially 45+ year old floats. The final goal,  after using whatever method one chooses, is to visually check the fuel heights in the nozzles at 2 1/2 turns down.

[jalexquijano]

49 minutes ago, Mark Maras said:

 No need to run the car for two minutes. In reality you just need to fill the float bowls to the new setting. if you're lowering the float setting be sure to remove some fuel from the bowls so they can refill to the new level. If you haven't readjusted the floats just pull the lids and measure with a caliper and readjust. 

 I've not used the 10 turns down previously but here's my understanding of the 10 turns vs the 2 1/2 turns. 10 turns down should be an accurate method of setting the fuel height. My assumption is when the floats are reinstalled they displace the fuel raising the level to 2 1/2 turns down. Now for the big IF. If all floats displace the same amount of fuel, the fuel level will rise to 2 1/2 turns down in all float chambers. I doubt if all floats are equal, especially 45+ year old floats. The final goal,  after using whatever method one chooses, is to visually check the fuel heights in the nozzles at 2 1/2 turns down.

These carbs were remanufactured by Ztherapy in 2014. Its the first time we open the float chamber to try to adjust them as the car was presenting issues when i drove during long idle traffic jams. Maybe they got banged during shipping. I am trying to sort this adjustment of the floats but the digital caliper is not helping.

[siteunseen]

First time since Ztherapy? 

[Mark Maras]

33 minutes ago, jalexquijano said:

These carbs were remanufactured by Ztherapy in 2014. Its the first time we open the float chamber to try to adjust them as the car was presenting issues when i drove during long idle traffic jams. Maybe they got banged during shipping. I am trying to sort this adjustment of the floats but the digital caliper is not helping.

 Step 1, Read post, # 31.

 Step 2, Put the calipers down.

 Step 3 , Floats installed, Remove the domes and pistons.

 Step 4, Using a flashlight, visually determine the fuel level in the nozzles.

 Step 5, Adjust the float tangs up or down until the fuel levels in the nozzles are 1/16" below the nozzle tops. Nozzles are 2 1/2 turns down during this procedure.

 Also, after each adjustment, move the floats up and down to ensure smooth operation, remove a little fuel from the bowls, reinstall the floats, crank the engine over or start it up for a few seconds to fill the float bowls to the new level. Recheck the fuel level in the nozzles.

 

 

[siteunseen]

17 hours ago, jalexquijano said:

Maybe they got banged during shipping. 

Don't try to blame your problems on Ztherapy or the shipping company, they didn't arrive in this shape.  

 

[psdenno]

As much as I've enjoyed watching this journey for the last few years, I think there are a few buggered up issues to sort out and it might be a good idea to start fresh by checking all possible causes of the exhibited symptoms before making any more carb adjustments.  Below are the troubleshooting steps from the factory manual.  Each item should be checked before moving on to carb adjustment. 

According to the manual, fuel pressure can be in the range of 3.41 to 4.27 psi.  More, or less, will cause less than optimal operation.  Fuel capacity is another issue.  Delivery should be 1600 cc (3 3/8 quarts) per minute (static test).  At this point, I'm leaning toward "operator error" rather than "mechanical failure".  In 47 years I haven't had that much of a problem with fuel delivery or carb adjustment with mine just following the factory manual and using a uni-syn and a Colortune.  Good luck!

Dennis

[jalexquijano]

Well last night a found a .55 inch wooden stick and adjusted the gap between the bottom of the float to the lid by blowing throught the gasoline hole. Lets do a test drive and see what happens.