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Thread: Float Height Adjustment ?

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    Registered User 240Z240Z240Z's Avatar
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    Default Float Height Adjustment ?

    OK, I searched the archives and didn't find much that helped me, so I'm asking here in hopes ya'll can.

    I want to check and/or adjust my float levels on my 72. The three manuals I have are pretty much useless, since two of them skip the issue and the other has a useless measurement from the top of the gas in the bowl to the inside of the cap, with the float in and the cap screwed in place. How in the heck are you suppose to measure that ????

    In any case, I don't know if they are currently set correctly, but I do know that when I pulled the floats out of the bowls the level of the gas at the bottom of the bowls was around .95" - .98" deep.

    How does one go about adjusting the float heights properly ?

    Note : I have the carbs where the legs that hold the floats are shorter on the front carb than the rear one for some unknown reason.
    1972, White w/red, 4 speed, 77K, All original.

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    My first inclination is to ask why you feel they need to be adjusted. I talk to more guys who have hopelessly messed their carbs up because of the burning desire to "adjust their floats".

    Give me a call tomorrow and I'll be happy to walk you through it. 503-587-9800
    Bruce Palmer
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    Default Float Adjustment

    I know I put this up before but I couldn't find it by searching, so here it is again.
    Last edited by geezer; 02-14-2011 at 09:52 PM.

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    Laidback Purist moonpup's Avatar
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    Here's a tip I posted a while back. It always worked for me.

    Use any bolt that your 14mm wrench/socket will fit and with the float bowl lid upsidedown and level, place the head of the bolt sideways between the float lid and the float itself.

    Now as you lower the float on to the bolt head, at the point it just touches the bolt, the float tab should now be just touching the needle. If it doesn't, adjust the tab so that it does.
    1971 240Z Tenth Anniversary
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    Registered User 240Z240Z240Z's Avatar
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    Quote Originally Posted by Bruce Palmer View Post
    My first inclination is to ask why you feel they need to be adjusted. I talk to more guys who have hopelessly messed their carbs up because of the burning desire to "adjust their floats".

    Give me a call tomorrow and I'll be happy to walk you through it. 503-587-9800
    Because I'm having starting issues as well as some power/performance problems, so I'm going through several things to make sure they haven't been jacked around at some point in the last 36 years. Thanks for the offer, I may just call you.
    1972, White w/red, 4 speed, 77K, All original.

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    Semi-retired admin Arne's Avatar
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    EDIT - I took too long composing this, you replied that the car isn't running well while I was typing. But I'll leave this post here anyway, as it may be relevant to someone else.

    I'm with Bruce on this one. Why mess with them if they're working? The float level is the primary mixture adjustment. If the car is running reasonably well, and the nozzle adjusters on the bottom aren't either bottomed or topped out, there should be no need to do anything with the floats.

    In many years of working with SUs (both British and now Datsuns), I've seen lots of decent running cars well and truly messed up because someone felt they needed to "re-adjust" the carbs. Fact is, once set, you shouldn't need to change them unless you tear them apart.
    Last edited by Arne; 05-13-2008 at 09:21 PM.
    Arne - Former owner, HLS30-37705, 7/71, 905 Red
    Car blogs - 240Z - Porsche 911

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    Registered User 240Z240Z240Z's Avatar
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    Quote Originally Posted by moonpup View Post
    Here's a tip I posted a while back. It always worked for me.

    Use any bolt that your 14mm wrench/socket will fit and with the float bowl lid upsidedown and level, place the head of the bolt sideways between the float lid and the float itself.

    Now as you lower the float on to the bolt head, at the point it just touches the bolt, the float tab should now be just touching the needle. If it doesn't, adjust the tab so that it does.
    That may work for one of the carbs, but I have the float lids that have different length legs for holding the floats, so the dimensions would need to be different for the front and rear carbs. I may be able to adjust for that though. Thanks.
    1972, White w/red, 4 speed, 77K, All original.

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    Laidback Purist moonpup's Avatar
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    Trust me, it works the same for both.
    1971 240Z Tenth Anniversary
    1975 280 Zzzap
    1977 280 ZXR



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    Quote Originally Posted by moonpup View Post
    Trust me, it works the same for both.
    He has a 1972. The float levels are not the same for both carbs.

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    Laidback Purist moonpup's Avatar
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    Those damn 72's get me every time!
    1971 240Z Tenth Anniversary
    1975 280 Zzzap
    1977 280 ZXR



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    Registered User 240Z240Z240Z's Avatar
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    Quote Originally Posted by geezer View Post
    I know I put this up before but I couldn't find it by searching, so here it is again.


    This is just what I needed! I just need to figure out which carbs I have and then make some gauges. It even adjusts for the short and long float legs which I have. Thanks!!!
    1972, White w/red, 4 speed, 77K, All original.

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    beandip beandip's Avatar
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    use a 1/2'' drill for a spacer.
    I'd rather die while I am living than live while I am dieing. CZC 1887 IZCC 12602 Member of NorthWest Z Car Club

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    Registered User 240Z240Z240Z's Avatar
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    Quote Originally Posted by geezer View Post
    I know I put this up before but I couldn't find it by searching, so here it is again.
    I'm assuming that the dimensions shown in the chart works for the spring load type of needle valves I have and is not specific to the solid type (if Datsun ever used those) ????
    1972, White w/red, 4 speed, 77K, All original.

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    Registered User 240Z240Z240Z's Avatar
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    Quote Originally Posted by beandip View Post
    use a 1/2'' drill for a spacer.
    .5" equals 12.70 mm, which isn't used according to the chart ???

    I think I need use 12mm (R) and 16mm (F).
    1972, White w/red, 4 speed, 77K, All original.

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    Well actually a bit more than that - the measurement is taken across a small lip, which would raise the gauge a mm or so... If you put a bolt head between the top and the float it won't be sitting on the lip...

    Make a gauge out of aluminum stock - it will be easier to hold and more accurate...

    FWIW,
    Carl B.

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    Quote Originally Posted by Carl Beck View Post
    Well actually a bit more than that - the measurement is taken across a small lip, which would raise the gauge a mm or so... If you put a bolt head between the top and the float it won't be sitting on the lip...

    Make a gauge out of aluminum stock - it will be easier to hold and more accurate...

    FWIW,
    Carl B.
    hmmm, looks like the dimension(s) and gauge take the cap lip into account. Thanks.
    1972, White w/red, 4 speed, 77K, All original.

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    Quote Originally Posted by 240Z240Z240Z View Post
    I'm assuming that the dimensions shown in the chart works for the spring load type of needle valves I have and is not specific to the solid type (if Datsun ever used those) ????


    I'm assuming your assumption is correct. This is not a spec that would be subject to change without notice.

    Carl - By measuring the way shown in the illustration in the TSB, wouldn't you think any 1mm lip would have been taken into account before specifying a measurement? Probably not critical because they allow 1mm of leeway in the spec parimeters and that would bring you to the smaller value if you started with the larger number. I do not see any 1mm lip on the set I'm looking at. But then again there are not any identification numbers on the float bowls of these either.

    Edit - 240Z240Z240Z - Looks like you figured that out. I didn't see your last post before this post.
    Last edited by geezer; 05-14-2008 at 01:15 PM. Reason: explanation

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    Be thankful you don't have Webers. They need to be adjusted for both up and down.
    72 240-- stock motor and drivetrain, 50,500 orig. miles

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    Registered User 240Z240Z240Z's Avatar
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    Quote Originally Posted by george71z View Post
    Be thankful you don't have Webers. They need to be adjusted for both up and down.
    I don't have webbers, but I do have these....

    http://rides.webshots.com/photo/1192...59523625rsnBCY
    1972, White w/red, 4 speed, 77K, All original.

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    Default Thanks for the info.

    Quote Originally Posted by geezer View Post
    I know I put this up before but I couldn't find it by searching, so here it is again.
    You have no idea how much searching I've done to find this. Thanks.

    Soon to be running well...........

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    Registered User Gary in NJ's Avatar
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    I'm resurrecting an older thread here (and something that has been discussed)...

    I note above in TS73-10 (dated 2/9/73) posted by Geezer that it shows different float heights for the '72 model year (~ 16mm front & ~ 12mm rear) yet the FSM indicates 14-15mm in figure EF-46.

    Which is correct? Why the different heights? If it has to do with the emissions system, and I have it disabled, should I stick with 14mm?
    Gary
    Guardian of HLS30-91415
    Previous Owner of a 10/70 240Z ('83-'85)

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    Gary, from what I can see there were several changes made in the FSM during the 1972 model year. There were enough changes that it was neccesary to publish a second manual to replace the earlier one that was issued for 1972. There were changes made in the carburetor section, the exhaust emission control system, as well as the engine electrical section. The technical bulletins were issued to the service & parts departments as changes were made and then entered in the new replacement manual which is meant to replace the earlier manual. Unfortunately, I don't have either of these manuals but I do have the TSB's that noted the changes. What is the publication date of your FSM? The replacement FSM was issued after July 3, 1972, and the last TSB relating to float adjustments for the 1972 models year was issued Feb 9, 1973. That is the one I would refer to, unless someone has more recent, relevent information.
    Last edited by geezer; 07-02-2010 at 08:11 PM.

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    Registered User Gary in NJ's Avatar
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    Ron,

    The manual that I have is the Service Manual (red cover) that is available for download. While the model year is noted, there is no revision date or number.

    I guess I'll add a float adjustment to my winter maintenance. The different values would explain why my mixture setting are different by more then a full turn.
    Gary
    Guardian of HLS30-91415
    Previous Owner of a 10/70 240Z ('83-'85)

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    Here is what worked for me.
    I made a gauge out of a piecs of aluminum. Then I flipped over the Carburetor and stated bending the float arm. Darn if those needle valves had a little spring in them. I could not get the level right. So I placed a piece of plywood in my bench vice and bolted the carb to it in a horizontal position, same as it would be in my Z. Now I figured that Fuel is a fluid and so is air. I took a length of fuel line and blew into it as I adjusted the lever arm. When the air flow stopped the needle was closed. Sure enough I got the gauge to where the float was where it was supposed to be. Bolted them up to my manifold and have enjoyed them ever since.
    As usual thanks Bruce for the Z therapy video and the help you have given me along the way.

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