Quadrajet Boiling

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NicolasB
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Re: Quadrajet Boiling

Postby NicolasB » Fri Apr 02, 2021 8:19 am

Also does this look fine? I’m only using one gasket for the carb, but not sure if it’s a base gasket or heat insulator. Is that enough to absorb heat? I checked if others had the same issue and found this on Edelbrock’s website: https://www.edelblog.com/tech-tips/resolving-heat-soak. I keep bringing this up because my issue mainly has to do with heat.
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NicolasB
Posts: 261
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Re: Quadrajet Boiling

Postby NicolasB » Sun Apr 04, 2021 10:00 pm

Also just another thought: can this situation cause me to have a lower mpg? When I calculate highway driving I get about 11.8 mpg at 65-75 mph. For city it’s about 6 mpg. Replaced spark plugs and wires, coil, converted to dual exhaust, and rebuilt quadrajet a year ago.

I also ran out of gas today and got stuck on the freeway so that was fun :lol: I drove it about 180 miles on one tank.

I just saw where the plugs are located on a video and it seems like I’d have to open the carburetor. I’ve never worked with the insides of one and am afraid to do so since the car runs at the moment.

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Otto Skorzeny
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Re: Quadrajet Boiling

Postby Otto Skorzeny » Mon Apr 05, 2021 5:54 am

Your fuel economy numbers are typical.

Yes, a carburetor running rich at idle is going to burn more fuel. When the engine is hot and idling, look straight down the carb throat. If you see fuel dribbling off the two "bull's eyes" in the center, your mixture is too rich. If you see fuel pooled on the throttle plate at the bottom, the mixture is too rich.

If the carb hasn't been rebuilt, it would be a good idea to have it done. Call Tim Hewitt at Daytona Parts Co. He does an excellent, careful job. He's rebuilt at least a dozen carburetors for me and personal friends. All of them are done perfectly and run perfectly when installed.

He runs them all on a test engine before sending them back.

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Otto Skorzeny
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Re: Quadrajet Boiling

Postby Otto Skorzeny » Mon Apr 05, 2021 5:55 am

Your carb looks very clean. Has it been rebuilt recently? If so, call the rebuilder and ask him if he sealed those plugs.

NicolasB
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Re: Quadrajet Boiling

Postby NicolasB » Mon Apr 05, 2021 11:46 am

Yes, I had the carburetor rebuilt back in May or June of last year. I called the guy who did it and asked him about the plugs, but he said that he didn’t know what I was talking about. I said “well plugs” afterwords and he still didn’t know what that was. I’m starting to think that he doesn’t work with quadrajets that often (he also didn’t fix the choke issue so that was one thing that I had to do myself).

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Otto Skorzeny
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Re: Quadrajet Boiling

Postby Otto Skorzeny » Mon Apr 05, 2021 6:54 pm

How does anybody who professionally rebuilds a Q Jet not know about the leaky plugs? It's a well known, well documented problem that GM figured out back in the 1960s. Lots of Toronados burned with suspicious engine fires back in the old days.

Call Tim Hewitt at Daytona and talk to him aboutr your carb trouble. He can probably help you pinpoint the issue.

NicolasB
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Re: Quadrajet Boiling

Postby NicolasB » Mon Apr 05, 2021 7:09 pm

Otto Skorzeny wrote:Your fuel economy numbers are typical.

Yes, a carburetor running rich at idle is going to burn more fuel. When the engine is hot and idling, look straight down the carb throat. If you see fuel dribbling off the two "bull's eyes" in the center, your mixture is too rich. If you see fuel pooled on the throttle plate at the bottom, the mixture is too rich.

If the carb hasn't been rebuilt, it would be a good idea to have it done. Call Tim Hewitt at Daytona Parts Co. He does an excellent, careful job. He's rebuilt at least a dozen carburetors for me and personal friends. All of them are done perfectly and run perfectly when installed.

He runs them all on a test engine before sending them back.


So I checked down the carb and I don’t see any fuel going off the “bulls eye” or pooled fuel, so I’m assuming the mixture is fine. For sure, I’ll cal Tim when I get the chance to see what the problem could be.

NicolasB
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Re: Quadrajet Boiling

Postby NicolasB » Tue Apr 06, 2021 4:01 pm

Called Tim today, and he sure does know a lot! So the carb is running rich, but I think the float is set correctly. What is really causing the problem is the fuel pump. I replaced it last year when the old one stopped working on an incline, but didn’t see the amount of psi that the new one pushes. In the manual, it says that the pressure should be between 5-7 psi. However, the one that I purchased from my local Napa is rated around 9 psi! He told me that I have two options (but I noticed that I have three):
1) Adjust the float.
2) Install a fuel pressure regulator.
3) Install a lower psi fuel pump. (My thought)

I have never opened a quadrajet before and he mentioned that it’s quite difficult to get to the float, so I was planning on getting a deadhead pressure regulator so I can manually adjust the psi. I’d feel like option 3 would be a waste of money and resources since the pump works fine, just pushes too much fuel.

NicolasB
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Re: Quadrajet Boiling

Postby NicolasB » Tue Apr 06, 2021 11:05 pm

Okay so I bought a deadhead regulator and it didn’t work at all. Fuel spewed from almost every area of the fuel filter no matter how hard I tightened the clamps. It’s a Mr. Gasket fuel pressure regulator and it only supported up to 6.5 psi apparently. I’m going to see if I can return it and get a lower pressure fuel pump instead. To my knowledge, RockAuto is the only place that has the correct one and they have one left in stock, which worries me about future parts.

NicolasB
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Re: Quadrajet Boiling

Postby NicolasB » Sun Apr 11, 2021 10:42 pm

Another update: Turns out the glass filter couldn’t handle the pressure of the regulator, so I just swapped it for a clear plastic one. Works like a charm! The car no longer wants to stall when I brake hard and doesn’t want to stall in traffic. Throttle response is almost immediate too. For the boiling issue, it seems like it went down a little, but is still present (but flooding after turning it he car off when it’s warm occurs less often). A friend of my Dad’s who knows a lot about classic cars said that my exhaust crossover is probably causing the issue. It’s possibly clogged and causing two of the cylinders on the intake manifold (near center) to look red, which means I’ll have to take it out soon and clean it.
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