Car stalling question
 

Hello,

I have a 347 Stroker Engine with street/race cam and a Holley 4 barrel 650. I have a problem which I don't know what's causing it. Under normal driving I have no problems, but if I do a very strong stop, hard braking, the engine dies. It sounds as though it's loading up. Here's the engine I have from Proformance Unlimited. 347 Sroker, 331 Crate Engines, Ford Stroker Engines, Ford Performance Engine
Anyone else experienced this problem? :confused:

Wayne Edgerton
Flower Mound, TX

I did this in the wrong sequence. Since I posted this I called Proformance Engines and he said I need to add slosh extenders to my carb, which is actually a 750 not a 650 like I posted. Apparently when I hard brake the gas sloshes forward and floods the car out.

Problem identified now I need to install slosh extenders.

Wayne Edgerton

Just in case one of you has the same problem and didn't know the answer to this, like me, here is what I ordered from AED Carburetion in Virginia.What I ordered is highlighted in red.

Virtually all single carbureted drag cars need rear jet extensions. During acceleration and high g-forces, fuel is pushed to the rear-most portion of the float bowl, uncovering the jets and creating a lean condition, which reduces performance. Our special bored stainless steel extensions have a special half-moon shape that assures plenty of fuel volume and clears the stock floats. Kit includes jet extensions, reusable gaskets, and reusable nylon bowl screw gaskets. Our new kit features machined float with custom jet extensions that gives you maximum float drop for high fuel demand applications.
We have two different Jet kits designed to meet all your jetting needs. These two kits contain (18) pairs of jets in a numbered reusable poly box for storage. That’s a total of 36 jets at a great price. Check "Billet" section for more options.


Part # Description Retail
5895 REAR JET EXTENSION KIT $16.95
5896 TRICK JET EXTENSIONS w/ MACHINED FLOAT "New" $34.95
6000 HOLLEY JET BOX(64-81)2 OF EACH $59.95
6010 HOLLEY JET BOX(82-99)2 OF EACH $59.95
* See "Billet Components" for Jet Plates & additional Jet Options

AED Performance Racing Carburetors, Holley Carburetors, and Performance Holley Carburetor Parts

Sounds like a good solution. 750 seems a bit big for that engine, but if it is running well with good response, more power to you! I hope the extensions fix the problem.

Very common thing, and easy solution, just do what the manufacter suggest and you'll cure the problem........

David

Wayne,
Pretty common problem.What they recommended would be vent baffles not jet extensions on the secondary.

Baffles help with prevent the fuel from sloshing thru the vent in the carb throat.Causing the stalling problem during hard braking.
The Jet Extensions help to prevent fuel starvation in the secondaries from the jet becoming uncovered on hard acceleration.

Example : Holley 26-89 - Holley Fuel Bowl Vent Baffle - Overview - SummitRacing.com

Lower the rear float level just a bit. Should work.

You are correct. When I originally called the engine builder I thought he told me jet extenders but when I called him back, after your post, he said yes it should be the vent baffles. He probably just mispoke the first time or I mis-listened %/

Thanks for the feed back on this it helped, I hope.

Wayne E

This answer wasn't the correct answer for me. When I took the float bowl off there already were baffle extenders on the metering body. I called the carburetor manufacturer, per the suggestion of the engine manufacturer Proformance Unlimited, and he told me to install rear jet extenders on the rear bowl jets and that will solve my problem. He explained it technically but to make it short, on hard stops the gas in the rear bowl flows forward creating a suction and allowing fuel to go into the carburetor through the jets thus flooding the engine. I'm going to install the jet extenders and if that solves the problem I'll post it, the technician was positive that would solve my problem. :confused:

Wayne E

Try putting the jet extenders on the primaries, that way the jets dont get uncovered under hard braking.

It worked for us !

Mike

What do you mean by primaries? There are two jets in the rear bowl and I will put an extender on each one.

Wayne E

Put the extenders on the two jets in the FRONT bowl.
Mike

I talked directly to the folks who built the Carb and they said they go on the rear to stop the gas from sloshing up against the jets when you hard brake. If you think about it, the gas will go forward in the bowl when you brake and in the front the gas would flow away from the jets where as in the rear it would flow up against the jet. He said the flow up against the rear jets causes a vacum of sort which draws fuel into the carb thus flooding it.


For those who like me didn't know how this works I took a couple photos. In the photos you can see the silver jet extenders installed. If you do this, the flat portion needs to point up. Also they go on very tight and you have to tap them on with a small hammer. The white plastic thing at the top of the photo is the baffle. Someone had mentioned I needed to add baffle extensions but in my case they were already installed from the factory so I didn't need to do anything with them. I also included a photo of the package the jet extenders came in, in case someone wants to order them.

I haven't driven the car yet, it's to early and I would wake up the neighbors, but if this doesn't work I'll make a post, but I feel comfortable this will fix my problem.

https://picasaweb.google.com/1166402...vK8Mmm1Y3MiwE#

Wayne E

Then how come the engine doesn't go rich or flood when you accelerate hard and the gas flows up against the primary jets ??

your barking up the wrong tree with your recommended fixes----seconary jet extensions are for acceration, and you already have the slosh baffles--your cure can be as simple as lowering the float levels to maybe even pushing in the clutch a micro second sooner when you come to a stop

He said that when your excelerating the gas is getting sucked into the carb so it's not the same issue :confused:

Wayne E

You're correct Jerry. What they told me was that the jet extenders are normally for acceleration but on other folks who've had the same problem as I'm experiencing they've put them on the rear bowl and it corrected the problem. I went out and tested it and it didn't correct my problem so I quess I'm up in the willow tree huh:rolleyes: The carb mfg told me that should have corrected the problem and he's going to get a couple of his folks together to see what they think my next move is. I think I'm going to give TomH440's idea a go and lower the float some.

I'll get this thing yet **)

Wayne E

You've got the extenders, why don't you just try them in the front bowl.
As I said , it worked for me.........several times.
Mike

jet extenders in the front bowl are a big no no!!!It will go lean as soon as you get on the trottle---

Ok I'm back, finally, and the problem has been fixed. I have been working with AED Performance who put together my carburetor for the guys who built my engine. AED Performance Racing Carburetors, Holley Carburetors, and Performance Holley Carburetor Parts These are some really nice folks who went out of their way to help me solve the problem and didn't charge me. I can’t say enough good things about them. But we went through several iterations to get there.

As I posted previously the first thing they had me do was put on rear jet extenders, which didn't solve the problem. They then decide to work with their engineers and fabricated me some parts to slide over the rear jets. Below is a link to the parts and what they looked like. They sent me a new smaller float so that their new part would work and two items to slide over the jets.

https://picasaweb.google.com/1166402...2G-bqros6C1gE#

I put them on and gave it a try and it still didn't work. They had me remove the carburetor and sent it to them. They said they found the spring was too tight on the new float, not my doing, and they made it not so tight. They then sent the carb back to me and I reinstalled it. It worked, but still was threatening to stall. They had me adjust the rear mixtures 1/4 turn leaner and had me lower the float 1/2 turn. They also had me raise the RPM up from 750 to 900.

That seemed to fix the problem. There's still a slight tendency to sound like it's going to stall out on a hard break but it quickly picks it back up. I can't get it to stall now. I'm not sure which one of those was the real hero but I guess it's working now so what the hey :D

Wayne Edgerton