gday,
I noticed today that the vent valve on my holley had fallen out and only the arm to open and close it was there. I took it to my holley tuner and he said if it runs ok with the hole plugged, then we'll just do that. So he plugged it and I took it for a run. Normally my car would splutter around 7grand in first (running a bit rich) but today it revved right passed 8grand to my delight. I don't understand how this little valve could of have made such a difference. Even the holley bloke was totally amazed. Anyone got ideas as to how this works? Also before today, it would rev to 8grand fine in 2nd, 3rd etc, but first would always have a splutter around 7grand. When tunning it a while ago, we first went a jet size bigger, and it was worse in first, (around 5 grand) 2nd was a bit worse as well and so on. So we figured it was definitly running too rich. We went smaller jets and the problem went away, except for first gear. I'm running a 465 holley on a bridgeport. I know this would normally be WAY too small, which is another thing I'm way confused about. Does it sound like its running too rich to you holley guys, or is it possible it could be something else? obviously I must have a small bridgeport for it too not want all that fuel right? And yes it is a full bridge. Sorry for the long post.

PS: Its the valve on the top of the float bowl, nearest the engine. The primaries float bowl I think? I think he said its called the vent valve.

cheers,
heb.

 

^

 

Is it realy a valve or just a vent tube that comes out of the bowl. If you turn a holley upsidedown gas just pours out of it. Many off roaders will extend these tubes up as high as posible inside the filter housing to avoide fuel sloshing. I wonder if you were accelerating hard enough in 1st gear to splash some fuel out of the vent?

 

kinda small for that engine aint it? u r aware that a 465 is for stock port engine, right? just imagine how fast it would be with the 650 that's recommended for a bp.

 

any pictures of this vent valve? i'm curious about it, too

 

I think he is talking about the tube in this pic that runs over the top linking the 2 float bowls together. This is holleys off road carb (I use it on my wheeling rig) the U-shaped vent is designed to keep fuel from spilling at extreem angles...it realy works.



EDIT: normal vent tubes just extend up an inch or so above the choke plate and don't link together.

 

I wonder if you are not emptying your float bowls and that is what is actually causing the sputter. 465 cfm on a bridge is way small. I was running a RB modified 600 cfm on my 13B and it was waaay to lean, even with larger jets, and it eventually got my motor. I am now running a 770cfm Holley with big jets to feed the supercharger and my porting (large street port on primaries and bridged secondaries). I think that would be overkill for a NA bridge but my fuel bowls don't empty any more. I could be way off on this, it is just a thought. A bridge requires more fuel, obviously, but you need more than just a bigger carb. You have to address the entire fuel system. It definately sounds like a larger carb would wake up the bridge in your case. Just my $.02.

JTB

 

if you need more fuel on a holley you could just get larger a larger needle and seat assembly. I run a 1.2 viton needle/seat.

I have no idea why it had that effect though...amazing.

Marques

 

Just ordered the Racing Beat street port holley for my car... waiting anxiously..

Dan

 

just be aware that the RB carb can take a few adjustments to run nicely. I think I have gotten it tuned alright, but its taken some playing around.

 

No no, its not that tube thing there. Theres a hole about 3cm in diameter on top of the float bowl closest to the engine. It had like a washer on top of it and a arm connected to that. The arm was linked to the throttle movement and would close this vent or hole on top of the float boat when about half WOT. I was told its there to add amospheric pressure to the float bowl for some reason. But its not all ways needed.

Before the 465 was on it, it had a 600. But my Tuner said they could hardly get the thing out of the driveway. My car goes pretty dam hard. I can beat 5.0 SS V8's. I'm sure its not running too lean, otherwise why would I need to go smaller jets to rectify my top end splutter? I'll try find a pic of what I mean.

cheers,
heb.

 

You can definitely get a bad studder from a lean condition, ever ran out of gas? My 465 holley 12a bucked and backfired and died. From my short experience, ever problem I have had comes from being lean, not rich. If its too rich, it might make less power and smoke, but it never stumbled for me.

 

yeah, i know the thing ur talking about. it was on the 465 i had but it's not on the 600 i'm using on my sp 13b. haven't got a clue as to what that thing was for.

 

Ok did you read my post? The stutter got worse the richer I went. And When taking off there is no surging or stuttering, its only at high rpm.

 

I've seen the little vent on Holleys before. I never really knew what it did other than move during throttling.