Quadrajet problems

nhramnl · 09-19-2017, 04:17 PM

I'm tending to support the "float too high" or "too much fuel pressure" suggestion. If the carb was fine but isn't now, your problem doesn't sound like a weather change issue. It sounds like a float that's too high (or the functional equivalent or that, too much fuel pressure) causing fuel to splash out of the bowl vent, into the primary venturis. If you leaned and richened it and the stumble wasn't affected, that would confirm that you have "uncontrolled" fuel entering the intake manifold. The car goes momentarily rich, stumbles and then gets on its way.

ss3011 · 09-19-2017, 09:16 PM

Quote:

Originally Posted by nhramnl

I'm tending to support the "float too high" or "too much fuel pressure" suggestion. If the carb was fine but isn't now, your problem doesn't sound like a weather change issue. It sounds like a float that's too high (or the functional equivalent or that, too much fuel pressure) causing fuel to splash out of the bowl vent, into the primary venturis. If you leaned and richened it and the stumble wasn't affected, that would confirm that you have "uncontrolled" fuel entering the intake manifold. The car goes momentarily rich, stumbles and then gets on its way.

Sometimes if the float is too high or too much fuel pressure , you can look down the primaries with the engine off , turn on the fuel pump and look to see if fuel is dribbling out the boosters . I had that problem , but could not fix it with a float level adjustment . I measured 7 psi fuel pressure . I did fix it by installing a new needle and seat . Edelbrock still sells the .145" needle and seat .

nhramnl · 09-20-2017, 09:42 AM

Interesting comment on the needle and seat, and definitely a possible contributor to the problem. I was having similar problems and called Dean Oliver, to discuss reasons why the car was so stinky, smoky rich. We confirmed the float setting and fuel pressure were right, and the next question he asked was "You're not using a .145 needle and seat, are you"? When I told him I was, his response was "Get it out of there; they flow so much fuel that they actually disrupt the fuel in the bowl". I went back to the next smaller needle and seat and the problem went away.

09-19-2017, 04:17 PM	#1
nhramnl Senior Member Join Date: Feb 2010 Posts: 507 Likes: 8 Liked 358 Times in 83 Posts	Re: Quadrajet problems I'm tending to support the "float too high" or "too much fuel pressure" suggestion. If the carb was fine but isn't now, your problem doesn't sound like a weather change issue. It sounds like a float that's too high (or the functional equivalent or that, too much fuel pressure) causing fuel to splash out of the bowl vent, into the primary venturis. If you leaned and richened it and the stumble wasn't affected, that would confirm that you have "uncontrolled" fuel entering the intake manifold. The car goes momentarily rich, stumbles and then gets on its way.

09-20-2017, 09:42 AM	#3
nhramnl Senior Member Join Date: Feb 2010 Posts: 507 Likes: 8 Liked 358 Times in 83 Posts	Re: Quadrajet problems Interesting comment on the needle and seat, and definitely a possible contributor to the problem. I was having similar problems and called Dean Oliver, to discuss reasons why the car was so stinky, smoky rich. We confirmed the float setting and fuel pressure were right, and the next question he asked was "You're not using a .145 needle and seat, are you"? When I told him I was, his response was "Get it out of there; they flow so much fuel that they actually disrupt the fuel in the bowl". I went back to the next smaller needle and seat and the problem went away.