I've got a Holley truck avenger 670cfm that's giving me problems with the fuel bowl vent tubes and can't seem to find any answers online. While the truck is running or even just starting up its spewing gas out of the vent tube and straight into the carb causing it to hard start and flood out. Don't know if it matters but the fuel is only shooting out of the secondary side of the vent tube. Any help or ideas would be appreciated
CK5
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Any Holley truck avenger experts out there?
- Thread starter 84bigblue
- Start date
This is most likely an issue with a stuck or bad float. The vent tube is just that, an air passage - no moving parts.
That's the general idea I was leaning to, mind if I ask the correct way to adjust the floats on a Holley (was always an edelbrock guy before I tried this Holley haha) I know that there's a sight hole and an adjustment up top. When I remove the plug for the sight hole however it shoots out a stream of gas, correct me if I'm wrong but that means the float is sitting to high? Was under the impression that it should only be a trickle of gas when the plug is removed
You are correct about the site hole.
Remove the set screw on top of the bowl and turn the large hex nut to raise / lower the float. The nut should turn by hand as the set screw is what locks it. This is usually done while the engine is running but you might want to turn the float down a fuzz before cranking it to control what's coming out of the site hole.
For giggles, try a few good taps around the bowl body to see if that changes how much fuel is coming out of the site hole. The float is simply stuck high rather than out of adjustment.
Remove the set screw on top of the bowl and turn the large hex nut to raise / lower the float. The nut should turn by hand as the set screw is what locks it. This is usually done while the engine is running but you might want to turn the float down a fuzz before cranking it to control what's coming out of the site hole.
For giggles, try a few good taps around the bowl body to see if that changes how much fuel is coming out of the site hole. The float is simply stuck high rather than out of adjustment.
If its a brass float,it might be sinking due to it filling with gas from a pinhole or leaky seam...foam ones can get soggy too and not shut the fuel flow off as it should..
Hmm it definitely shouldn't have a leak in the float or anything as the carb is only a couple of months old. But as they say anything's possible haha. Any who I went ahead and adjusted the secondary float and it seems to have done the trick and isn't shooting out fuel through the vent tube as of now so +1 for that hah. But it still seems to stall out, but the truck seems to be idling on the low and so I suppose I'll be playing around with that now 
I've sold rebuilt carbs in the past, that sat on warehouse shelves long enough to let the float corrode,or the accelerator pump dry up--they do have a shelf life..also some carbs with foam floats might not have had ones rated for ethanol put in them..
Maybe I'm just unlucky,but my experience with all Holley's excepting a few Holley Economaster carbs that performed great, is they are always in need of fiddling and adjusting endlessly,when they aren't flooding,stumbling on acceleration,etc...
It took me a month to get one "dialed in" with the correct accelerator pump and adjustments to cure an off idle "bog",and I had to try several different secondary opening diaphram springs before I got it to run good enough to satisfy me..then winter set in,and it started aggravating me again..
I spent hours and $$$ on parts and still wasn't that impressed..to me the Holley's seemed too sensitive to weather conditions,humidity and temparature..it'd run great one day,then sucky the next ,if it rained,or cooled off..in winter they liked to backfire and blow power valves if I opened the choke too soon..(I had a hand choke on them )..
No doubt they do make an engine run much better once dialed in right--but you may never find that sweet spot..
I prefer a stock carb like a Q-jet--rebuild it once,throw it on,adjust the mixture and choke--and drive it thousands of miles,trouble free..and they behave much better off road than a Holley by far..
Maybe I'm just unlucky,but my experience with all Holley's excepting a few Holley Economaster carbs that performed great, is they are always in need of fiddling and adjusting endlessly,when they aren't flooding,stumbling on acceleration,etc...
It took me a month to get one "dialed in" with the correct accelerator pump and adjustments to cure an off idle "bog",and I had to try several different secondary opening diaphram springs before I got it to run good enough to satisfy me..then winter set in,and it started aggravating me again..
I spent hours and $$$ on parts and still wasn't that impressed..to me the Holley's seemed too sensitive to weather conditions,humidity and temparature..it'd run great one day,then sucky the next ,if it rained,or cooled off..in winter they liked to backfire and blow power valves if I opened the choke too soon..(I had a hand choke on them )..
No doubt they do make an engine run much better once dialed in right--but you may never find that sweet spot..
I prefer a stock carb like a Q-jet--rebuild it once,throw it on,adjust the mixture and choke--and drive it thousands of miles,trouble free..and they behave much better off road than a Holley by far..
Iv always heard qjets make great off road carbs, have yet to be able to find one for a reasonable price to play around with however haha. But as far as the truck avenger goes besides this problem I'm currently having with it, it's been a night and day difference compared to my edelbrock. I do however know what you mean about the constant tweaking, as I did replace the discharge nozzle and accelerator cam and such right out of the box
