New to SU carbs, have a few questions

[Dan222000 5]

Hello,

I am fairly new to SU carbs and have a few quick questions.  I have a 1973 Datsun 240z with 3 hole SU carbs.  I was driving the car the other day and noticed that I was loosing power at WOT.  I got the car home and it was idling low and died out on me in the driveway.  I popped the hood open and noticed that the rear carb was leaking from the lower nozzle head or hose onto my header (I don't want to burn my car down).  I also noticed that the float bowl was loose (loose meaning I can take my hand and rock it back and forth)and some fuel was coming out of the top float nipple.  Sound like I have a couple of issues here with the float and/or lower jet nozzle/nozzle hose.  Below are a few newbie questions I have.

 

1. Should the float bowl be loose?  I can take my hand and rock it back and forth.

2.  Should the overflow nozzles have a hose to direct the fuel away from the header?   

3. Are the nozzle hoses hard to come by?  I did a quick search and couldn't find anything online.  Where I can get some replacement hoses?

4. How hard is it to remove the jet and is there a seal or gasket that can be replaced here?  

5. How hard is it to completely remove the carb from the car?

 

Thanks,

Dan

Edited July 15, 2019 by Dan222000

[Mark Maras 977]

 Yeah, one can rock and or twist the bowls. Ztherapy.com is a good source for parts, an excellent DVD and rebuilds, should the need arise. The lower nozzle hoses come with the rebuild kit. Don't try to substitute another type of hose. These hoses are super floppy to prevent the nozzles from binding.

  I'd start by pulling the bowl cover, the floats, and the needle and seat. Clean the crud out of everything and reassemble. Oops, two things. It might be a good idea to check the float height (per the shop manual or DVD) and when you remove the bowl covers, wrap the gasket in aluminum foil and press it flat in a book. They will dry out in just a few minutes and curl up into a Pringle if left exposed to the air. Anyone, It's been a while since I looked at the float bowl vent hoses but as I recall they plumbed into the air filter base. Hope that's right. If it's not, it would still be a good place for them.

 I'd get the rebuild kits and the DVD or at the least a shop manual. There's nothing complex about the refresh. Cleanliness is the key. I haven't checked but there's probably lots of videos on YouTube.

 The carbs are easy to remove. The base nuts are a bit fiddly and one has to take extra care when reinstalling (adjusting) the choke cables.

[240260280 1,907 1 Vehicles]

If you dig in, the photos in this thread may be helpful:

https://www.classiczcars.com/forums/topic/40425-su-reassembly-step-by-step-part-1-tear-down-torn-n-tattered-worse-for-wear-n-tear/

 

 

[siteunseen 2,909 5 Vehicles]

13 hours ago, Dan222000 said:

Hello,

I am fairly new to SU carbs and have a few quick questions.  I have a 1973 Datsun 240z with 3 hole SU carbs.  I was driving the car the other day and noticed that I was loosing power at WOT.  I got the car home and it was idling low and died out on me in the driveway.  I popped the hood open and noticed that the rear carb was leaking from the lower nozzle head or hose onto my header (I don't want to burn my car down).  I also noticed that the float bowl was loose (loose meaning I can take my hand and rock it back and forth)and some fuel was coming out of the top float nipple.  Sound like I have a couple of issues here with the float and/or lower jet nozzle/nozzle hose.  Below are a few newbie questions I have.

 

1. Should the float bowl be loose?  I can take my hand and rock it back and forth.

2.  Should the overflow nozzles have a hose to direct the fuel away from the header?   

3. Are the nozzle hoses hard to come by?  I did a quick search and couldn't find anything online.  Where I can get some replacement hoses?

4. How hard is it to remove the jet and is there a seal or gasket that can be replaced here?  

5. How hard is it to completely remove the carb from the car?

 

Thanks,

Dan

Nissan has them. Bought these a year or so ago. Call and give them these numbers and they can tell you if they're still available.

[Dan222000 5]

Guys,

Thanks for all the help.  Looks like I'm going to give it a crack and clean/ freshen up my SU carbs. 

 

Thanks again!