Stall out question

[Loadmaster]

OK, I have a little 302-fuel problem. Car has less than 600 miles on her. Carb is an Edelbrock 650 atop a RPM Performer manifold. All new parts. Start up, idle, acceleration, are all-fine. When I come hard on the brakes the engine stalls. She starts right back up, but I'm going out on a limb here and guessing its not supposed to die. Any ideas would be great

Load Clear

[Aussie Mike]

Don't know if this will help but fuel slosh from the float bowl vent tubes might be your problem. I'm not familiar with Edelbrock carbs but on Holley carbs under hard braking or acceleration fuel rushes forward/backward in the float bowls and sloshes up out of the vent tubes. These are 2 tubes with slash cut ends that stick out of the top of the carb into the aircleaner area. The fuel that sloshes up falls down into the intake and floods the engine.

It's easy fixed on a Holley, get a 6" to 8" piece of rubber hose that will fit over the vent tube. connect each end of the hose to the 2 float bowl vents making a u shape. Cut a hole in the tube at the peak of the bend that faces upward. This will still allow your float bowls to vent but if fuel sloshes up the vent it has to travel all the way up the tube. If it makes it to the top it will just run down into the other float bowl.

This is an old drag racers trick. The fuel sloshing under hard acceleration fuel would richen up and bog down the cars on the line.

Cheers

[Pete C]

Load,

Holley makes a "whistle" that fits into the vent slit and prevents "fuel slosh", engine flooding under hard braking. This little device is essential with the dual quad set up since they are generally mounted backwards. Perhaps the Edelbrock folks have a similar solution.

Cheers, Pete C

[rdorman]

There is also foam that can be put in the fuel bowl that helps control fuel slosh. Check your float level, it may be to high.
Rick

[Hal Copple]

I have thought this thru, and have a different opinion. First, assuming you have your float levels set right, if you have an aggressive, hot cam, and have a fairly low engine idle speed, at low rpm, idle, when you are braking, you are only running off the front primary side. The fuel flows to the front of the bowl, and depends on engine vacuum to pull it back thru the jets and into the boosters, and down into the intake.

I just think an aggressive cam allows enough vacuum at low rpm to do this. It just can't pull gas back and into the engine, hence the stall at low speed braking. On my car, if i make a slow speed sharp turn, like into a neighborhood street, the same thing happens, the gas flows to the side and my engine can't pull the gas back into the jets.

Long ago, i just started rocking my right foot over onto the throttle, just a bit, to keep my idle rpm up just a bit when i come to a stop or make a sharp turn at low speeds, i am no longer aware of doing it, i just have scuff marks on all my right foot shoes.

By the way, i have the vent whistles, and properly set floats, it is just in my opinion the above cause.

[Loadmaster]

Thanks for all the input. you guys are a wealth of knowledge.

Load clear

[RallySnake]

Loadmaster,

I hear you and I HATE this problem. Particullarly, surging in high g-force turns.

With the Carter-type carb (read Edlebrock) the only thing that will help is more fuel pressure. If you kick it up to about 10 psi with a high performance fuel pump it will really help the problem, but your fuel mileage will be worse. With my Quadrajet (same thing), I run two electric pumps, one stock and one 7 psi Carter. Switch on BOTH for autocross.

I'll let you in on the real racing solution for this problem. It can be completely solved on a Holley with the use of jet extensions. They are little tubes that you solder onto your jets to reach the far side of the float bowl. They act like minature reservoirs that keep the fuel where you need it. There are also screw-on jet extensions that move the jet outwards. These require notched floats for clearance. For autocross, I ran a Holley 650 DP with soldered-on jet extensions on all four jets and it never stalled in any rapid speed changes or high g-force turns. Try it, you'll LIKE it!

Paul

[agro1]

Mine only does it when I am in netural coming to a (hard) stop. If you keep the revs up it shouldn't happen.

[RedBarchetta]

Originally posted by Hal Copple


.... the gas flows to the side and my engine can't pull the gas back into the jets.

Hal, have you ever looked into jet slosh tubes? You can epoxy them onto the end of the jets and they create "extentions" to pull fuel from the front of the primary fuel bowl.

[Doug Axelrod]

The motor-impaired among us (and I may be alone, here), want pictures !

[MidOHasp]

I notice the problem when I mash the brakes and clutch from speed. Was doing some braking tests recently and stalled it every time. Also noticed it around corners. This is some good advice!!

[flipper35]

Holley or BG if you have the money. Don't know if the off road kit will help with the jake brake issue, but with the Eddy and autocross the fuel will slosh from the bowl on one side to the other. Though I like the Weber based carbs on the street with the good low end resonse compared to the Holley I had, I am thinking of switching back. May get a 4-corner idle one at that and be done with it.