holley 4175 setup
Dr. Detroit
Joined: Mar 2012
Posts: 10,097
Likes: 4,027
From: New Braunfels Texas
Have you put a small insulator gasket underneath?
It IS the float but now you have to figure out why.....if the fuel boils, the float will drop, causing the 6” shot out the top.....
Jebby
Le Mans Master
Joined: Mar 2004
Posts: 7,493
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From: Little Rock AR
Make sure the carb has a heat shield and consider blocking the heat riser passage in the intake manifold. The problem is heat related. Heat riser flap could also be sticking closed. Not uncommon. Those nasty open heat slot intakes are still out there on the road.
Thread Starter
Le Mans Master
Joined: Jun 2019
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From: Loveland
NEW,,,, Brass Holley float and seat. I haven't been able to find a heat shield for the 4175. Will the shield for the 4160 work? Where is the heat riser passage?
Last edited by kodpkd; Aug 1, 2019 at 09:55 AM.
Le Mans Master
Joined: Mar 2004
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From: Little Rock AR
Under the carb. Look for the dreaded slot with a hole at each end. The passage was concealed on later intakes but it is still there.
Race Director
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Heat Shield
When you installed the new float what exactly did you do to adjust the float level?
Have you ever done a fuel pressure test?
Does your car have a fuel return line that has been blocked off?
Last edited by MelWff; Aug 1, 2019 at 02:07 PM.
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so those Holley instructions stated almost parallel to the float bowl?
you didnt check the fuel pressure? A high pressure could be fine when running but blow the needle off the seat after you shut it off.
so did you look at the Quadrajet heat shields?
https://www.google.com/search?q=quad...w=1600&bih=757
you didnt check the fuel pressure? A high pressure could be fine when running but blow the needle off the seat after you shut it off.
so did you look at the Quadrajet heat shields?
https://www.google.com/search?q=quad...w=1600&bih=757
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Le Mans Master
Joined: Mar 2004
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From: Little Rock AR
You will need a thin stainless steel heat shield for a Quadrajet to lay down on the intake first and then a new Quadrajent carb gasket on top of that at the minimum. You could just toss the crappy intake and go back with a nice lightweight aluminum intake. You just cant run it the way it is now.
Drifting
Joined: Apr 2017
Posts: 1,377
Likes: 282
From: Bedford New York
I still firmly believe this is the problem. You probably have the 3919803 casting number intake manifold. It has an exposed heat riser passage across the front that ROASTS the front bowl on the spread bore carb on top of it. Pull the carb off and see the bottom for yourself. It will look like it was bolted to the top of a bar-b-que.
You will need a thin stainless steel heat shield for a Quadrajet to lay down on the intake first and then a new Quadrajent carb gasket on top of that at the minimum. You could just toss the crappy intake and go back with a nice lightweight aluminum intake. You just cant run it the way it is now.
You will need a thin stainless steel heat shield for a Quadrajet to lay down on the intake first and then a new Quadrajent carb gasket on top of that at the minimum. You could just toss the crappy intake and go back with a nice lightweight aluminum intake. You just cant run it the way it is now.
Asking because my heat shield is sandwiched between 2 gaskets. Rebuilding my QJet now, so this is a timely thread. Thanks.
Le Mans Master
Joined: Mar 2004
Posts: 7,493
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From: Little Rock AR
Never heard back from OP so....
I would toss the heat slot intake in the trash first. Gaskets and heat shields are just the cheap fix.
If you dont have the open slot manifold you can block the passage on the drivers side but be sure to eliminate the heat riser functionality first when you do that.
I would toss the heat slot intake in the trash first. Gaskets and heat shields are just the cheap fix.
If you dont have the open slot manifold you can block the passage on the drivers side but be sure to eliminate the heat riser functionality first when you do that.
Race Director
Joined: Apr 2003
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From: Tampa, Florida
Does the stainless shield sit directly onto the manifold carb mounting surface? Or, is there a need for a gasket to first sit on the intake manifold, under the stainless steel heat shield, then another gasket on top of the heat shield?
Asking because my heat shield is sandwiched between 2 gaskets. Rebuilding my QJet now, so this is a timely thread. Thanks.
Asking because my heat shield is sandwiched between 2 gaskets. Rebuilding my QJet now, so this is a timely thread. Thanks.
Thread Starter
Le Mans Master
Joined: Jun 2019
Posts: 5,481
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From: Loveland
Never heard back from OP so....
I would toss the heat slot intake in the trash first. Gaskets and heat shields are just the cheap fix.
If you dont have the open slot manifold you can block the passage on the drivers side but be sure to eliminate the heat riser functionality first when you do that.
I would toss the heat slot intake in the trash first. Gaskets and heat shields are just the cheap fix.
If you dont have the open slot manifold you can block the passage on the drivers side but be sure to eliminate the heat riser functionality first when you do that.
I did check the gas cap. It is vented to allow air into the tank, when gas is used, air needs to go into the tank to not create vacumn. It isn't vented to release pressure when the tank get hot and pressurized.
Last edited by kodpkd; Jan 16, 2020 at 01:10 PM.
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Have you done a fuel pressure test?
Do you know exactly what fuel pump is on the car?
Your original 68 gas tank is not vented, all venting is supposed to be performed by the cap.
from the factory your car had a fuel return line which would have bled off fuel pressure after the engine was turned off.
Do you know exactly what fuel pump is on the car?
Your original 68 gas tank is not vented, all venting is supposed to be performed by the cap.
from the factory your car had a fuel return line which would have bled off fuel pressure after the engine was turned off.
Last edited by MelWff; Jan 16, 2020 at 03:40 PM.
Thread Starter
Le Mans Master
Joined: Jun 2019
Posts: 5,481
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From: Loveland
Have you done a fuel pressure test?
Do you know exactly what fuel pump is on the car?
Your original 68 gas tank is not vented, all venting is supposed to be performed by the cap.
from the factory your car had a fuel return line which would have bled off fuel pressure after the engine was turned off.
Do you know exactly what fuel pump is on the car?
Your original 68 gas tank is not vented, all venting is supposed to be performed by the cap.
from the factory your car had a fuel return line which would have bled off fuel pressure after the engine was turned off.
I believe the fuel pump is stock. I installed a fuel pressure regulator set at 4 psi, it didn't help the hot flooding issue. BUT,,,,,,,, I didn't realize the car HAD a fuel return line on it. It doesn't have one now. Maybe you broke the code. I'll see if I can find how to hook up my holley 4175 to a fuel return line. Thanks...
Thread Starter
Le Mans Master
Joined: Jun 2019
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From: Loveland
I have the GF-432 filter and the metal lines ordered. I am going to hook up the return line. I believe my flooded start problen is because of back pressure and no return line on my fuel feed. I want to use the fuel filter bracket. I have checked online,,, and the parts suppliers for how to bolt it to the engine. Even Keen parts diagram doesn't really show how to bolt it up. Does anybody have a pic of the stock 327 350 hp fuel filter bracket bolt position? Please. All I can figure is the intake manifold corner bolt.
Race Director
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Look at the image in this thread, appears to attach to air pump bracket
https://www.corvetteforum.com/forums...n-a-69-sb.html
https://www.corvetteforum.com/forums...n-a-69-sb.html
Last edited by MelWff; Jan 20, 2020 at 12:30 PM.
Thread Starter
Le Mans Master
Joined: Jun 2019
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From: Loveland
I recieved the "AC Delco GF432" fuel filter. My question: Is there supposed to be a restriction in the smaller 1/4 inch return line port? If I blow into the main fuel line inlet hole, air comes out the fuel output and the 1/4 inch holes the same, NO restrictions. I tested a different brand return line filter, if you blow into the intake, air comes out the output port, but is very restricted out the 1/4 inch return port. It doesn't make sense the 1/4 inch port isn't restricted, unless there is supposed to be a restriction in the return line. Maybe the ebay GF432 filters are cheap defective copies. Does anybody have a NOS GF432 filter they can blow into?
Last edited by kodpkd; Jan 23, 2020 at 07:55 PM.