Hi all.  Trying to set the float level on my stock '76, L-48.  First Question: The carb kit only gives one value for all 1976, Chevrolet 350's: 5/16".  I'm assuming that's correct?  Second, I've looked at several different web pages regarding where that 5/16" is measured from.  Some say right at the toe (edge furthest from the needle and pivot), others say 3/16" in from the toe, and one said at the back (edge nearest the pivot and needle).  Again, I'm assuming that the toe (or very close) is the correct reference point from top of float to top of bowl casting.  The weird thing is I had to adjust it quite a bit - maybe 3/16" or 1/4" - to make those assumptions work. 

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JB weld is perfect for the plugs on the bottom of the bowl. Be sure to not put too much, as that could cause the epoxy to hit on the base-plate when you put it back together, creating a whole NEW problem!(cracked base-plate)

Check out Ken's carb article here...click on "Ken's Projects", then "Quadrajet". It gives excellent advice on setting float levels, and has pics to show how.

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Joel Adams
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Mine is a 76 L-48 also and I just finished the 2nd rebuild of the Q-jet.  I did the first right after I got it a couple years ago so I could get a passing emission test.  However, the carb had some bigger issues like worn primary throttle bushings so I recently tore it down again and sent the throttle body out for replacement bushings.

The long and short of it is that both carb rebuild kits give the same value for the float adjustment which is slightly different from yours (9/32").  One of the kits listed specs by carb number (very helpful) rather than just by year of install and GM division. The first kit was a carquest, but the second kit was a much better TOMCO that I ordered from Zip.  This kit has more replacement parts and a substitute replacement fuel valve that replaces the needle and seat (higher flow and more positive function).  If you want to provide your carb number (drivers side, main body) I will let you know the float measurement from the instructions I have.

The advice in the Ken's link for setting up the float is good.  You must make sure the hinge in the float is held down with light pressure on the needle seat to measure the float (otherwise it will be off).  Measuring as close to the end of the float as possible (before it curves over).

Good luck

Thanks for the offer to look up the float setting for me.  The number on the carb is 17056207 (matches the number I have in the Corvette Black Book for 1976, 180 hp, manual trans).  Knowing the exact float setting could help me. 

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  I apologize for the delayed reply (haven't read the forum for a few days).  I have attached a scan of the carburetor setting (hopefully it is legible).  Your carb number is in the line immediately below the horizontal line (which has my carb number in it).  It looks like 9/32" is the float setting for both carbs.  There are bigger brains in the forum than mine who might help diagnose your problem, but if you are sure it is fuel related, my experience might help.  Shortly after I bought the car, it developed a serious fuel starvation problem (sometimes the car would die and other times, just barely run).  A visual test showed the carb had plenty of fuel when hand pumped and I ended up replacing the fuel pump (which showed slightly low pressure) and dropping the tank/cleaning.  The tank was pretty clean and the fuel pump was not the problem as the miss persisted.  I rebuilt the carb (kind of quick and dirty) because I had to get an emission test.  That solved the problem.  I have had some other related carb issues as previously mentioned (worn bushings which would never let the idle settle in properly) and decided to do a more thorough rebuild.  I currently have a 4175 holley on the car, but intend to put the rochester back in this spring because I think it will still run better with a thoroughly rebuilt rochester carb.  I located a copy (on the web) of Lars Grimsrud's article on "How to Tune a Q-jet (basic)".  This article was very helpful in understanding problems and fixes for Q-jets.  The Haynes Rochester Manual was helpful also.  I hope this helps you.

I have Lars Grimsrud's article on "How to Tune a Q-jet" as a MS Word doc, if anyone wants it...I'm not sure if it is e-mail friendly, but I'll sure give it a try.
It is VERY detailed, spec-wise, with no pics, but a lot of tuning tips.

btw, the best "quick test" for water in the fuel is to drain some out in a clear container, and let it sit. The water will separate, and settle to the bottom. It will be quite noticeable. Also, you can get a really bright flashlight, and look down into the fuel tank from the filler. If there is a lot of water in the tank, it will be visible at the bottom. (This is much easier to do on the pre-75 cars than the post-75 cars...)

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Joel Adams
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"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"

Thanks for the scan of the chart, Tom43xy. Do you mean both should be 13/32"? (9/32" looks like the measurement for the accelerator pump).   The 13/32" is 3/32" different from what I set mine at -- interesting how the two carb kits gave such different numbers. I'll try yours, though, since it actually references the carb number. Guess I'll have to pull the top off the carb again. I also have the Cliff Rugles book - very good book, but it's weak on the issue of the float settings.   






(email addy modified for your protection)Adams' Apple2008-01-28 06:29:13

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On it's way, Dave...

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Joel Adams
C3VR Lifetime Member #56    
My Link


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"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"

Daveo76:
You are correct.  I did misread the chart and the correct setting is 13/32".  I confirmed this is the same setting on the instructions from both carb kits I have used.  Sorry that I misquoted it.  Now I'm second guessing what setting I used on mine (I think I used the right measurement, but will probably pull off the top to double check).

As someone else noted, you can't really tell about water in the tanks with bladders.  The bladder is black in color (at least mine was), so you would need a lot of light and a bigger hole than you have through the fuel filler.

I also have the Lars Grimsrud article electronically and can e-mail it to you if you have any trouble getting it.

Thanks

Can I get one of you to send me the Lars Article on Tuning.  I had my carburator overhauled but the idle needs tweeking and the idle mixture is off.  I would have used him but he was down for a while so I had it done locally. 

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Mike & Marcia


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Comin at-choo, Mike!

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Joel Adams
C3VR Lifetime Member #56    
My Link


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"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"

hey joel could you send the article..my carb is in rebuild now and when i get it back saturday i will need some help if it needs tweeking.

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Done...I have converted this to a "zipped" file, to make it easier for me to e-mail.

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Joel Adams
C3VR Lifetime Member #56    
My Link


(click for Texas-sized view!)             NCRS

"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"

Got it. 

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Mike & Marcia


(Click for bigger look)

got it, thanks joel

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