Car stalling question

[392cobra]

Originally Posted by wedgerton

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.

Anyone else experienced this problem?

Wayne Edgerton
Flower Mound, TX

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

[tomh440]

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

[wedgerton]

Originally Posted by 392cobra

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

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

[wedgerton]

Originally Posted by wedgerton

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.

Wayne E

[Mike Huddart]

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

It worked for us !

Mike

[wedgerton]

Originally Posted by Mike Huddart

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

[Mike Huddart]

Originally Posted by wedgerton

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

[wedgerton]

Originally Posted by Mike Huddart

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