My car has decent brakes, but it's not like I spent 5k on them. After a tough street race this past weekend, when we were approaching the next stoplight, I let off the accellerator and hit the brakes hard. The car flooded and nearly died. It blew a rich cloud (black exhaust), which I found embarrasing. This has happened before when I'm on it, suddenly let off and hit the brakes. I think this is BS. The carb is a 750 double pumper. Any ideas? Is this a common problem?
I don't know the fix but I can tell you that my Buick will stall under heavy braking with my Holley and it did it with the Q-jet too.
Andy, do you have a dashpot installed on the intake? This will soften the abrupt throttle "let go" when you pull your foot off the pedal, and allow a slower deceleration, keeping the car from stalling. You could probably make a bracket to work with a stock one for the Holley.
flooding and rich If your floats are set high, fuel maybe exiting the vent tubes and running into the throttle bores. I have experienced this with a holley but not a qjet. Worth a try to lower floats and see if you still have a problem.
Try lowering the rear float level about 1/8" below the sight plug. Also make sure the rear metering block has the white plastic vent baffle installed in the top of the metering block. This will help with fuel sloshing out of the rear vent tube on hard braking. Sometimes you run into this problem with fuel dripping out of the rear boosters as well. Since the boosters sit lower than the vent tube the fuel can drip out of them as well. Unfortunately there is no good cure for this. :af: :af: Mike
I agree that it's worth a try. I'll do it this weekend. I know that the fuel just barely eeks out, so they are not super high. I have to do something, though. This is a street car, and sometimes it gets pushed hard. Nothing quite like hauling butt, then getting a stalled engine when you're trying to stop!
Makes me wonder what road racers / NASCAR does. There's no way that flooding the engine under hard braking would be acceptable....
I am suprised that your Q Jet did the same thing. I was hoping for better fuel control with that kind of carb design.
not to hi-jack,but sbbuick,Did you have to purchase anything to make your Holley work with the GM linkage?Im going to purchase a Holley 4160 #0-80457S. Thanks, Philip
You just have major fuel slosh in your float bowls. Like someone else said, get the white "whistle" that pins to the metering block and extends into the float bowl. It keeps fuel from sloshing out the vent. It's made by Holley and usually comes in the Master rebuild kit, or you can buy it seperately. Have fun.
The only thing I needed was a ball for the accellerator cable. It came with the carb. Good luck with it.
I know that it has one in the primary bowl, but I never checked the rear. Aren't these a standard issue part for Holley?
You're right, I don't know why I didn't think of it before( getting old). That is the purpose of the dashpot, to keep the RPM's up long enough to burn the extra fuel in the intake. I need to see if I have one somewhere. I'm guessing I didn't have it installed when I was running the q-jet.
Andrew, Did you get it fixed yet??? I can give you the P/N's you need for the vent baffle and daspot and bracket if you need it. :TU: Mike
Thanks, Mike. No, I haven't worked on it yet. Now the primary needle and seat appear to be sticking even though I replaced them just a couple of months ago. I found this out because I had raw gas driping on the Intake after the car was shut off. Unreal. I had that Holley since 1992, and it performed very well up until just a few months ago. Now, it's being a total PITA. I can't count how many times it's flooded me out.
Which carb are you running? Center or side hung floats? Are you using brass or nitrophyl floats? I had seen some intermittent flood issues with the brass floats over the years. I prefer the the nitrophyl. Send me a PM with your address and I can send you a goody bag with some new floats, needle and seats etc.... if you let me know which carb you have. :grin: Mike
My car does the same thing at the end of a drag run. I have a real old 1050 holley that had a power valve in both ends. After I removed the rear power valve and put in a plug and put in jets about 10 numbers bigger to make up for lack of power valve the flooding on braking got much worse. I also have jet extentions in the back. I have a piece of hose on the bowl vents. One end on the front bowl vent and it goes up and over to the rear bowl vent with a hole cut in the hose at the high spot for a vent. I don't think its flooding from the vent because the bigger the back jets are the worse it floods on hard braking. I brake with my left foot so at the end of a run I push on the gas pedal some to keep it from dying, and when it gets slowed down to a safe speed I put the trans in neutral and clean it out before the return road comes up and pop it back in gear to drive it back.
