Jump to content
Dan222000

New to SU carbs, have a few questions

    Recommended Posts

    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

    IMG_9777 (2).jpg

    IMG_9778 (1).jpg

    Edited by Dan222000

    Share this post


    Link to post
    Share on other sites

     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.

    • Like 1

    Share this post


    Link to post
    Share on other sites

    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

    IMG_9777 (2).jpg

    IMG_9778 (1).jpg

    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.

    20190715_103016.jpg

    • Like 1

    Share this post


    Link to post
    Share on other sites

    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!

    • Like 3

    Share this post


    Link to post
    Share on other sites

    Create an account or sign in to comment

    You need to be a member in order to leave a comment

    Create an account

    Sign up for a new account in our community. It's easy!

    Register a new account

    Sign in

    Already have an account? Sign in here.

    Sign In Now

    ×
    ×
    • Create New...

    Important Information

    By using this site, you agree to our Terms of Use. We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.