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Discussion Starter · #1 ·
Ever since break in on my 406 I have been fighting an over-rich condition with my holley. First I changed powervalves because mine was blown, I have a 6.5 in it now. I then noticed a vacuum leak at the base plate of the carb, the 'footprint' of the carb was larger than the gasked and leaked vacuum like a mother. I also put 70 primary jets in it, I had to take those out and put the original, very small 65's in just so it wouldn't smoke like crazy at idle. I have a fuel drip at the secondary diaphragm, it slowly drips onto the intake manifold, causing a puddle of fuel next to one of my intake runners. (edelbrock torker) Today, I was looking straight down the carb while it was idling and I noticed fuel dripping down from the secondary boosters (the things that stick out into the middle of the barrel, above the butterfly). They were both dripping at the rate of about 1 per second. Why in the world would they do this? And why the secondaries? Is my float level too high? This is a 4010 model 600 cfm holley. My plugs are brownish/tan color except for the outer edge of the metal electrode, it is still black - I can smell the fuel at idle, so I know it's running way too rich. There's gotta be something wrong with the carb if I run 65 jets to keep it from smoking with a 600 cfm on a 406!

Any ideas?

Thanks!


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1971 Chevelle Malibu - 406 sbc TH350

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The floats in your secondary circuit are either sticking or improperly set. I would check the float level and adjust as necessary. If that does not work, change out the needle and seat on that side as there may be trash causing the condition. Once you fix the problems with the secondaries you may have to revisit the jetting in your primary side as those 65's will probably be too small for that motor.. Watch your plugs.
 

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Adam..I'm not sure about your series of carb ..but on other vacuum secondary holleys there is an adjustment screw that will set the static opening on the secondaries at idle...check to see if your carb has this and that its not set too far open ....

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You can sleep in your car,but you cant drive your house.
Tony. H . 406 powered , Mohave Gold , 72'Malibu
 

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I saw that 4010 on your video when Steve showed it to me 2 weeks ago. You guys sure love your starter fluid


that carb needs to be rebuilt.....I had one of those laying around for a while and when i put it on my truck, it did EXACTLY what you are describing.

My solution..I through it out and bought an E-brock
 

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Discussion Starter · #5 ·

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Hoffbug, I think you are thinking about the double pumper mechanical secondaries, not vacuum. To my knowledge vacuum secondaries don't have that screw that your referring too, but I know that mechanical secondaries do.



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Chris Dagenais
Saskatchewan
'71 Malibu with a home built 454!
"Because of my velle, i'm broke, cut, bruised, tired, dirty, sweaty, and loving EVERY minute of it"
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Plus, main jet size has no effect on idle quality. At idle, the engine its fuel from the carb through the idle circuit in the carb. Somethings definitely wrong for it to be dripping at the booster venturis. Either the secondary throttle blade is open too far, or the primary is open too far and causing the engine to idle through the main jets, which as you know, would cause it to idle extremely rich. This carb may need a rebuild, just to get everything adjusted properly again.
It wouldn't hurt to look at the float levels and make sure they're set right.
 

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What is your idle speed to high i bet like the abouve post says.To set it up each blade should just be showing the transfer slot any more and the main jets are exsposed causing an over rich mixture.

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Don Pell 66 396Beaumont.
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<BLOCKQUOTE>quote:</font><HR>Originally posted by Gandalf80:
Hoffbug, I think you are thinking about the double pumper mechanical secondaries, not vacuum. To my knowledge vacuum secondaries don't have that screw that your referring too, but I know that mechanical secondaries do.
<HR></BLOCKQUOTE>

Chris..I'm not sure about the series of carb that Adam has(he will have to look if the other stuff is OK)... but my Holley 750 vacuum secondary carb model #3310 has this little set screw that adjusts how far the throttle plates can close on the secondaries...Its very small and the screw head is on the underside of the base plate... Again I'm not shure about the other series of Holley vacuum secondary carbs..

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Tony. H . 406 powered , Mohave Gold , 72'Malibu
 

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Adamlym

Your secondary float is not adjusted correctly or you have some junk stuck in the needle and seat.

I have had the same problem and it is easily fixed. Pull out the needle and seat and make sure its clean, you may even want to replace it. Then stick it back in and ajust the float level until fuel just starts to run out the sight window. Problem should be solved.

A stuck secondary float on the 4010 will cause fuel to drip from the vacume actuator. Fuel will also spill into the secondary venturies and you should have alot of black smoke and wet black marks on your garage floor near the exhaust. Been there done that.

Clark
 

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Discussion Starter · #11 ·
<BLOCKQUOTE>quote:</font><HR>A stuck secondary float on the 4010 will cause fuel to drip from the vacume actuator. Fuel will also spill into the secondary venturies and you should have alot of black smoke and wet black marks on your garage floor near the exhaust. Been there done that.<HR></BLOCKQUOTE>

Exactly the problems I am having - Thank you so much! I'm going out to work on it now. I wondered why I was getting black marks on the floor. Thanks again everyone!

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1971 Chevelle Malibu - 406 sbc TH350

Pic of my car
another picture of my car
Picture of my 406
Picture of my and my buddy's '65 4-4-2
My site
 
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