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Float level dimensions

Discussion in '308/328' started by ltoth, Jul 26, 2012.

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  1. ltoth

    ltoth Rookie

    Nov 20, 2008
    43
    heidelberg,ont.
    Full Name:
    leslie toth
    #1 ltoth, Jul 26, 2012
    I had the engine out, so it made sense to reguild the carburators, setting the float levels at 48mm and 58mm, giving a 10 mm travel on all 4 carburators. Installing them was as follows: intake manifold, a 1.5 mm or so black gasket, the 4.75mm black plastic spacer/insulator, another black gasket and finally the carburator. Did the synchronizing, set the timing AF7 for both. The engine starts the moment the ignition key is turned and runs smoothly around 900 RPM up to 140F. as the temerature is climbing towards 170-180F, the RPM climbs to 2000 and stays on 2000. Also while running at 900 if i give a little gas it goes to 2000 and stays there. The return springs are fine an all 4 carbs. I thought there might be some leak between the carbs and the manifold so I tightened the nuts and while doing it I noticed gasoline leaking between the carb body and the manifold/spacer, but only the carb for cyl. 7 and 8. Removed that carb, I did not see anything wrong with the spacer( it was new), i also checked the float level (48 and 58), and the litlle valve-it moved freely. While doing this I also checked the Haynes Weber book, according to them 42 DCNF should be 48 and 56.5, all others 50 and 58.5. Anybody ? Any comments ? Thanx guys !
     
  2. ltoth

    ltoth Rookie

    Nov 20, 2008
    43
    heidelberg,ont.
    Full Name:
    leslie toth
    #2 ltoth, Jul 26, 2012
    Oh, the car is a 1978 308 GTS...
     
  3. Sledge4.2

    Sledge4.2 F1 Rookie

    Oct 19, 2007
    4,786
    Marin
    Full Name:
    Geno
    #3 Sledge4.2, Jul 26, 2012
    Did you screw the end caps on the likage rods down too tight? They should have some slop, which allows them to return smartyl. Sounds like you may be binding up
     
  4. pbat

    pbat Karting

    Aug 5, 2011
    59
    Qld Australia
    Full Name:
    Peter B
    #4 pbat, Jul 26, 2012
    Hi Leslie, first the webers should be 40 DCNF on that car not 42. When you check the float level make sure the 48mm is when the valve is just stopping the flow not with the extra spring on the needle. Another thing that will make it idle high is if the butterfly’s are not sitting properly against the side walls when closed. To check this you need to remove the carby and remove the choke inner sleeve that sits down the carby barrel. Then put the carby up to light so you came see if light passes the butterfly, loosening off the butterfly screws will adjust this. When you refit the carbies you can use some petroleum gasket glue on the base gaskets to make sure there is no vacuum leaks, especially if the carbies are a little warped on the base. Also when you have the carbies apart it is a good idea to remove the linkages and springs over the open bearings and put grease all over the open bearing, this will prevent air vacuum leak on the butterfly shafts. I didn’t ask if you did remove the butterfly’s, if you did you may have not refitted them properly.

    Peter
     
  5. pbat

    pbat Karting

    Aug 5, 2011
    59
    Qld Australia
    Full Name:
    Peter B
    #5 pbat, Jul 27, 2012
    Leslie, you didn’t say how many turns out you have the mixture screws? They need to be around 3 turns out, if you have it too lean then when you rev the car it will stay high revs.
     
  6. ltoth

    ltoth Rookie

    Nov 20, 2008
    43
    heidelberg,ont.
    Full Name:
    leslie toth
    #6 ltoth, Jul 28, 2012
    Hi Guys ! Thanx for the replies.
    -linkage rods move freely,turn easily up and down, but no free play fore and aft, and the 4 carb springs return the linkages to their original, low rpm position.
    - mixture screws were turned all the way in and turned 3 turns out, followed by turning out the ones whre the barrels were spitting (runnung lean) by 1/2 turn at the time. Air corrector jets one open one closed as needed.
    -yes, I know the 308 carbs are 40DCNF, I am just quoting what the Weber manual writes:"42DCNF should be 48-56.5 mm (I also have a 69Indy with 42DCNF), and all others,36DCNF, 40DCNF ! , 44DCNF should be 50-58.5 mm. Travel should be 8.5 mm. I did not remove the butterflies.I am getting one new plastic insulator from Trutlands, and to be on the safe side one from Pierce. In the meantime the plastic insulator I have on this carb is new, made new gaskets, bought a tube of petroleum gasket glue. On all 4 carbs the floats were set for Ferrari 48-58 numbers with the spring loaded balls not pushed in, but I will take out the new needle valve, even though it moves freely.Greasing the ball bearings is a good idea too. Still with all this done, if I have vacuum leak why not on the lower temperature, why does the engine speeds to 2000 rpm when it reaches operating temperature ?
     
  7. pbat

    pbat Karting

    Aug 5, 2011
    59
    Qld Australia
    Full Name:
    Peter B
    #7 pbat, Jul 29, 2012
    Last edited by a moderator: Sep 7, 2017
    It still sounds like a vacuum problem, like one of the butterflies is open a little. I have some brand new 40 DCNF original Italian Webers you can buy if you can’t fix these.
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