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Carburator Adjustment for Holley 4v 4160
#1
Need assistance with making adjustments to my carb (Holley 4 barrel 4160). I do have some images and text from the Internet on what to do. However, where do you hook up the vacuum gage to the carb for adjustment. I also read that the idle mixture adjustment is seated all the way in and backed out 1 turn. Is this a valid adjustment? Also the idle air adjusting screw not sure if my carb has that. See attachment


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#2
Attached is the Holley 4160 manual.
When making engine adjustments (carburetor or timing) with a vacuum gauge you need to use full manifold vacuum.
Setting idle mixtures adjustment screws to 1 to 1-1/2 turns out is a good starting point.
Idle air and idle mixture are the same screw, it adjusts the air/fuel mixture in the idle circuit.
I have also attached a theory of carb operation paper from Holley, which should help some.

.pdf   Holley 4160.pdf (Size: 1.12 MB / Downloads: 52)

.pdf   Holley Carburetor Tech Info.pdf (Size: 130.46 KB / Downloads: 39)



“If you can't explain it simply, you don't understand it well enough.”
--Albert Einstein
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#3
Much better documentation than what I have. Thanks.
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#4
on most carbs like holley full manifold vacuum will usually be on the base plate. make your float adjustment first with the engine running so that fuel just tries to barely creep out the hole you don't want it to be pouring out. make sure your on flat ground made that mistake once. make sure when you get the gauge on it that the needle doesn't move back and forth. you want it to be set so that it stays nice and steady. adjust mixture screws a little at a time. i usually set mine the same for both as far as turns. for the street its usually fine. but for racing sometimes they will be slightly different. when you screw them in to bottom and back out 1 1/2 for the baseline. make sure you don't crank down on them, just enough so they seat all the way in. the slots might not be the same and that's fine. the holly's are great for adjustment very easy. oh and one more thing check you accelerator pump adjustment as well after you get your initial tuning done. i have the same carb on my 68 f100 good luck she will prrrrrr in no time Smile
ryan
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#5
Don C;63269 Wrote:Attached is the Holley 4160 manual.
When making engine adjustments (carburetor or timing) with a vacuum gauge you need to use full manifold vacuum.
Setting idle mixtures adjustment screws to 1 to 1-1/2 turns out is a good starting point.
Idle air and idle mixture are the same screw, it adjusts the air/fuel mixture in the idle circuit.
I have also attached a theory of carb operation paper from Holley, which should help some.

What Don said is right on target. Just make sure that the screws are exactly the same ratio out.
Once you get it lined up with the smoothest idle, I always will run the screw all the way in and count the turns so I know where I'm at.
But before you do, notice the position or clocking of your screw, then count how many turns until it just bottoms out. Then back it out that same number to put it back where it was. Do the exact same with how ever many turns you did to the otherside. When your done, the screw slots will NOT be clocked in the same direction, that is how it should be.
Anymore then 2 1/2 turns out and you probably have another issue as that would be pretty fat.
Also, you didn't say if this was a new or rebuilt carb? If rebuilt, you should always check the cork idle screw gaskets to make sure that they are sealing properly. If they are torn or falling apart, change them.




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