Holley bowl/needle/float question
Thread Starter
Intermediate
Joined: Jan 2012
Posts: 46
Likes: 0
Holley bowl/needle/float question
So I was having problems with my carb... i think its related to the primary fuel bowl/float setup. With the car idling if i crack the lock screw or open the sight hole gas goes flying everywhere. So I tight back up and went around to shut off the car. After I shut it off i went back over and cracked the lock screw again. Gas flew everywhere until the pressure inside the bowl dropped. I decided to pull the bowl off just to have a look. It seems the float is a center hung float i guess it coudl have drained while i was pulling the bowl off but after it was off i shook it and felt no fluid in it. The needle however when I move the float up the needle moves up when I move it down the needle sticks up for a little bit then falls back down a couple seconds later. In my mind this would cause a lean senario not a over pressurized fuel bowl? How can I clean up this needle valve or can I? and Does this sound like my problem and I am seeing it wrong?
Last edited by Silenttrouble; Mar 9, 2012 at 03:39 PM.
Le Mans Master
Joined: Dec 2003
Posts: 5,727
Likes: 38
From: Fremont CA
You should post this in C3 tech part of the forum.
From what I gather, you are removing the float sight plug (should be a brass flat blade screw on the side of the bowl) and having fuel run out of it. You need to adjust the float height by using the float adjusting NUT at the top of the float bowl, there is a slotted screw which LOCKS the hex nut below it that performs the function of adjusting float needle height. With the float bowl removed, you can turn it upside down and perform a "quickee" adjustment by setting the top of the float (flat part closest to top of the float bowl adjusting nut in the normal position, now it is closest to the bottom with the bowl inverted.) Adjust the top of the float so it is just below the 2 flat bladed screws to the rear of the float bowl and this should be "in the ballpark" for the correct float setting. Make sure you place a wrench on the adjusting nut before trying to loosen the set screw or you risk the possibility of stripping the float bowl where the needle screws in.
If you decide to change the needle you will need to loosen the set screw then remove the needle by turning the float nut counterclockwise. If you do replace the needle, I like to lube the "O" rings with WD40 before installing them into the float bowl. Have fun.
From what I gather, you are removing the float sight plug (should be a brass flat blade screw on the side of the bowl) and having fuel run out of it. You need to adjust the float height by using the float adjusting NUT at the top of the float bowl, there is a slotted screw which LOCKS the hex nut below it that performs the function of adjusting float needle height. With the float bowl removed, you can turn it upside down and perform a "quickee" adjustment by setting the top of the float (flat part closest to top of the float bowl adjusting nut in the normal position, now it is closest to the bottom with the bowl inverted.) Adjust the top of the float so it is just below the 2 flat bladed screws to the rear of the float bowl and this should be "in the ballpark" for the correct float setting. Make sure you place a wrench on the adjusting nut before trying to loosen the set screw or you risk the possibility of stripping the float bowl where the needle screws in.
If you decide to change the needle you will need to loosen the set screw then remove the needle by turning the float nut counterclockwise. If you do replace the needle, I like to lube the "O" rings with WD40 before installing them into the float bowl. Have fun.
Thread Starter
Intermediate
Joined: Jan 2012
Posts: 46
Likes: 0
I have it all apart... gas was flying out of the lock screw hole in the top and/or out the sight glass... the needle seems to be sticking up when i move the float up and down... float doesnt have a hole in it i submerged it and checked for bubbles.
Race Director
Joined: May 2006
Posts: 18,729
Likes: 2,579
If the engine is running and you loosen the screw you will get gas squirting out. The needle may stick slightly but under pressure it will not. You have to remove the site plug determine whether you want to go up or down with the float level, turn off the engine and wait a few seconds for the pressure to drop and then loosen the screw and adjust the nut. Then restart the engine and check if the level is where you want it. Notice in the instructions below they make the adjustment with the engine off.
http://holley.com/data/TechService/T...Carburetor.pdf
http://holley.com/data/TechService/T...Carburetor.pdf
Last edited by MelWff; Mar 9, 2012 at 04:25 PM.
Le Mans Master
Joined: Apr 1999
Posts: 6,134
Likes: 46
From: Raleigh North Carolina
The bowl is not pressurized. The line leading from the fuel pump to the carb fuel inlet is pressurized while the engine is running, and can hold some residual pressure when the engine is first turned off.
Burning Brakes
Joined: Apr 2007
Posts: 1,039
Likes: 62
From: Kona Hawaii
Gave up!
Just plain gave up on my Holley,after spending many hours and $$ I sprung for a new carb and all the troubles went away!Got one of these:
[IMG]
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Carb review http://forums.corvetteforum.com/c3-t...or-review.html
Good luck.....
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[/IMG] Carb review http://forums.corvetteforum.com/c3-t...or-review.html
Good luck.....
Burning Brakes
Joined: Apr 2007
Posts: 1,039
Likes: 62
From: Kona Hawaii
Summit carb has been updated from the original Holley version.This carb is running great,very ez to setup.It's a very nice street carb.You can even get to the secondary butterfly adjustment without removing the carb.Don't care for the power valve location but it isn't that bad. Price is great,just over 2 benji's.Check out the review.....Just got tired of constantly fiddling with the Holley.Was thinking about EFI,but since the Vette is running so good now I'll hold off on that idea.2k will buy a few more gals of fuel..That's what this forum is all about,getting different views for things that affect our cars and suggest new idea's for the owners..
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Le Mans Master
Joined: Mar 2008
Posts: 5,948
Likes: 72
From: Oxford MA-----You just lost the game!!!!
Keep the shiny side up!
Scott
Burning Brakes
Joined: Apr 2007
Posts: 1,039
Likes: 62
From: Kona Hawaii
There must be a million Holley carbs that are running great out there.I tried and tried to get mine to work great too.No success, rebuilt it twice with all new parts even new billet metering blocks.Still not running right.
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Was thinking EFI already but not in the budget.So looked for a low cost option in the mean time and presto the Summit carb appeared and now the troubles are over! I will take the Vette up the coast tomorrow and see how the MPG's are.Stay tuned for my carb update in a day or two..Aloha's
[IMG]
[/IMG]Was thinking EFI already but not in the budget.So looked for a low cost option in the mean time and presto the Summit carb appeared and now the troubles are over! I will take the Vette up the coast tomorrow and see how the MPG's are.Stay tuned for my carb update in a day or two..Aloha's
Le Mans Master
Joined: Apr 1999
Posts: 6,134
Likes: 46
From: Raleigh North Carolina
Not getting personal here but you must have missed something. Don't toss the carb in the trash. Somebody with "Holley" skills (e.g.- me) could fix it. The throttle shaft bore is probably worn out.
Team Owner
Joined: Jul 2008
Posts: 23,419
Likes: 22
From: In limbo
St. Jude Donor '13-'15, '17 thru '22
The Holley double pumper carbs are prone to getting the needle valve stuck open. Having the bowl under pressure sounds to me like this could be your problem. I have been using one for 4 years, and have had to clean them out twice (the second time was yesterday). Capevettes has a similar set-up to mine, and reports the same issue. It only takes a 5/16" socket and about 15-20 minutes to clean them out, and then it runs like new again.
Burning Brakes
Joined: Apr 2007
Posts: 1,039
Likes: 62
From: Kona Hawaii
Holley was pushing way too much fuel in the motor.Plugs were always fouling .Idle mixture adjustment screws had no effect,turning in or out.New metering blocks,power valve, made no difference.Followed all the advice on the forum,and other Holley Tech papers.Heat soak was also a problem,tried heat shield and thicker base gaskets,helped but still fuel boil after shutdown.My best efforts netted a decent running motor but I still wasn't happy.Oh well try a new carb! Troubles have all gone away,wish I had made the change sooner and saved me some $$$.I'm really pleased with this new Summit carb,how it holds up in the long run remains to be seen.....Aloha's
Melting Slicks
Joined: Aug 2008
Posts: 2,200
Likes: 3
From: Lehigh county Pennsylvania
There are tiny passages in these carbs. Worst thing is to have this crap they call gasoline, dry inside them. Even carburetor cleaner won't remove it. So you end up throwing good $$$ after bad and solve nothing. Then buy another brand which has virgin passageways and condemn the Holley. But the dope who mistreated the Holley gets off scott free. No offense to scottyp99.
WOW, I've used my #4776 600cfm and #4779 750cfm double pumpers going on 30 years. I must be just plain lucky NOT to have suffered this seemingly common complaint. I wonder why?
The Holley double pumper carbs are prone to getting the needle valve stuck open.
Melting Slicks
Joined: Aug 2004
Posts: 2,220
Likes: 6
From: www.Z16.org North/West Pennsylvania
The Holley double pumper carbs are prone to getting the needle valve stuck open. Having the bowl under pressure sounds to me like this could be your problem. I have been using one for 4 years, and have had to clean them out twice (the second time was yesterday). Capevettes has a similar set-up to mine, and reports the same issue. It only takes a 5/16" socket and about 15-20 minutes to clean them out, and then it runs like new again.
Le Mans Master
Joined: Mar 2008
Posts: 5,948
Likes: 72
From: Oxford MA-----You just lost the game!!!!
There are tiny passages in these carbs. Worst thing is to have this crap they call gasoline, dry inside them. Even carburetor cleaner won't remove it. So you end up throwing good $$$ after bad and solve nothing. Then buy another brand which has virgin passageways and condemn the Holley. But the dope who mistreated the Holley gets off scott free. No offense to scottyp99.
WOW, I've used my #4776 600cfm and #4779 750cfm double pumpers going on 30 years. I must be just plain lucky NOT to have suffered this seemingly common complaint. I wonder why?
WOW, I've used my #4776 600cfm and #4779 750cfm double pumpers going on 30 years. I must be just plain lucky NOT to have suffered this seemingly common complaint. I wonder why?
Is there anything you can recommend for cleaning a carb that is in this condition? Or are they just a lost cause, and the trick is to not let a carb get into that kind of condition? If you've been using the same carbs for 30 years, what's your secret? When I change the strings on my guitar, I save the old strings, and use 'em to clean the tiny little passages in carbs, but there are some that ya just can't get at. You just can't get the guitar string to make the turn sometimes.
Keep the shiny side up!
Scott
Race Director
Joined: May 2006
Posts: 18,729
Likes: 2,579
Get a gallon bucket of carb clearner and leave the components in there for 1/2 hour. Then use compressed air to blow all the passages clean. Guess if you have really bad situation you can leave it in the bucket for another 1/2 hour.
Melting Slicks
Joined: Aug 2008
Posts: 2,200
Likes: 3
From: Lehigh county Pennsylvania
According to the owner of a small engine shop in my neck of the woods who deals with carburetors all the time, the penetrating qualities of carb cleaner will not overcome the capillary action or surface tension in those tiny passageways once the, lets just call it varnish for want of a better word, dries inside. It happened to me on carbs for an engine-driven welder, brushcutter and chainsaw. I wasted $$$ on rebuild kits to no avail.
Go ahead and bash Holley carbs to your heart's content. No skin off my nose. IMO, most of it is undeserved.
Go ahead and bash Holley carbs to your heart's content. No skin off my nose. IMO, most of it is undeserved.
