Car stalling out during hard braking??

Hi, I put a new performance brake system on my car. I noticed when I was donig my "test" runs to try them out that the car is now stalling out if I haul it down quickly from just about any speed over 30 mph.

Am I just sloshing the fuel away from the primary jets? I do have jet extension on the rear, but don't think I should put them on the front as that would kill my quick acceleration runs :Brow: .

Is there a cure for this? What's wrong?

Phil

 

Put the drum brakes back on.
Problem solved.
I'll be glad to "dispose" of those disc brakes that are giving you all these problems too.
p
:laugh:

 

Phil,

sorry to tell you that mine has done that too, except I'm only running the stock disc brake setup. Sure hope you didn't pay too much for those high performance brakes when stock disc brakes would have killed your engine just fine. :laugh: :laugh:

 

You could be getting raw gas from the rear bowl coming out of the vent tube and going right down the carb. I've known several people who've fought with this problem at the strip. They will connect the vent tubes together with a piece of rubber hose that has a slot cut out at the top. I'm sure you've seen what I'm talking about. Good luck

 

Sorry but I haven't seen that. But I can picture it in my mind and maybe I'll give it a try.

My car came with factory front discs, I upgraded to ceramic pads and cross drilled/slotted rotors along with braided lines to replace the rubber ones.

 

I was following your other post and I think your brake upgrade is awsome. Sounds like your having a lot of fun with the testing also. :TU:

 

Yea, it's been fun. Been getting some interesting looks from folks driving past as I launch and then slam on the brakes about 7 seconds later and watch everything go up in smoke, tire smoke that is.

As for the cost, as I heard someone once say, "It's only money. You can always make more!"

 

All the extensions in the world arent going to help if your float levels arent correct! I had the same problem.
:Smarty:

 

Questions....

How's your in-gear idle speed? I assume you are running an automatic? Be sure it is set to the minimum. How about cam and ignition timing? What is your converter stall speed? Sometimes bigger cams with stock converters and low idle speed can do this. How about the overall tune on the car?

Of course, you should go through some of these other suggestions too..... :laugh:

Phil

 

Car idles at around 750-800, is an automatic, I have clear bowl screws to see the fuel level, ignition is 34 total, converter is a custom 3300 stall.

 

How hard is it to restart? Any smoke when you restart the car?

 

It's starts back up pretty easy. Not sure about the smoke as there is tire smoke all around, but possibly.

 

If there isn't a smell of gas or black smoke like the engine flooded and died, I doubt it's gas spilling over from the secondaries. This is an interesting problem as it seems like you have everything covered. If you have a good, strong ignition, idle is set high enough, timing is good, the converter isn't too tight for the cam and it runs good other wise, I only have one thing I can suggest. You may on track with uncovering the jets for the primaries.

You might try doing another stop, waiting for the smoke to clear and then restarting the car. Look for the smoke. o No:

 

Let's see, do another run down the street and slam on the brakes? Well, allright, if I have to................

 

Have your tried a brake test with the transmission in neutral? I doubt it is anything with the tranny but this would eliminate it as a possible problem.

 

I've never heard of that, but I can give it a try.

 

Is the carb a Q-jet? It's common to miss the phenolic spacer that holds down the fuel slosh. I had cut 1/4" off of my spacer and the new 12" brakes would stall out the car at first. I put in a regular spacer and it was fine.

 

Holley 950HP.

 

May just have to switch to an EFI system now, technology follows itself. Good luck and keep us posted. Kevin :3gears:

 

There are only 3 possible things happening. 1. too much fuel. 2. too little fuel. 3. A load is coming throught the transmission with your more powerful brakes in the rear (least likely with a torque converter.) Eliminate 2 of the 3 and you will know what the problem is (sure sounds good if it is not your problem :Smarty: )

I had the same type of problem with my ski boat doing a spin manauver. I could make the boat slide backward and load the prop (torque converter) up and stall the boat. All I had to do was kick the idle up a little to overcome the load. I have heard that Hollys are good for side to side G loads and Qjets are good for for and aft G loads due to the respective float designs.

I do know that Ford used a device on Hollys that would slow down the last bit of throttle closing. Just looked up the part it is called a dashpot. It is listed as an anti stalling device. National Parts Depot #9b550-3a. This is for a 428 with 735cfm Holly.

If you can do a plug read after a stall you should know what the fuel situation is.

As good as your car runs has to be very minor problem.