Sooty day’s...

[7173Vert]

No go on the Spring replacement... still too much fuel at idle... Keep at it...

We have tried everything to adjust the carb, absolutely no improvement. We then decidied to run the carb on his 289 engine to see how the engine/carb run (yeah, i know, a 289..., but it was more about confirmiong that my 429 engine is not adding to the problem...). It still ran rich on his engine which then eliminated any issues with my 429cj as being a possible source to the problem. Pressure tested the carb overnight, no apparent leaks. Tore the carb down again and re-checked the factory settings for the carb. Found an issue with the setting for the metering rods (at the base is a sealed plug area for these. Found it to be 0.020" to high, so this was readjusted. Reinstalled on the temporary 289 engine... and we were now able to see some good vacuum at idle and the idle mixture screws are wanting to adjust as they should (obviously super sensitive on the 289)... Will reinstall the carb on my engine on Sunday and hope that we have found the issue... 

 

[7173Vert]

Carburetor fixed. CO was eventually reduced to 4.5%... You would never guess the cause... Think aftermarket rebuild kits... Two year’s I struggled with this. 

 

[Hemikiller]

wrong base gasket included in the kit?

 

[Carolina_Mountain_Mustangs]

Great to hear you have made progress.

I was at my friends shop last week and ask his opinion on the issue. He right off said bad casting like another member had said. He said that 90% of them do the same thing. He also showed me the epoxy on the bottom side like yours has.

I told him that you had bench tested and the fuel did not run out. He is finishing up a 69 Pontiac Firebird HO that uses the same carburetor. He said it had same issue when he got engine together. He bench tested and no leak but he had learned in the past to take it outside and sit in the sun on a hot surface. When he did sure enough it leaked. The heat opens up the flaw in the casting and pours extra fuel in.

So it this happens again he suggests that you seal the inside with a good fuel resistant epoxy.

 

[7173Vert]

wrong base gasket included in the kit?

Bingo... You knew this and didn't tell me  :huh:  :whistling:  Anyway, there is a sealed factory adjustment that had to be opened up and readjusted to make up for the extra thick gasket that the rebuilder had used. With this completed, we were now able to finally see adjustment on the idle mixture screws for the first time, probably since the car was restored. At the end of the day, i now have a blue printed Q-Jet... 

Now, just as soon as this was rectified, I have a major ignition issue... I lost my Pertronix during the trials and tribulations with the carb fix the past couple weeks. Put points in temporarily and it seemed to run ok. We had swapped out the original yellow top coil as it was reading an infinite resistance, if i under stand this correctly. BTW, it appears to be getting 12v at the coil. Shoould be less? I thought there was a resistor in the wiring harness near the ignition switch, if my memory serves me well? I never tampered with the wiring in any way, when I put the Pertronix in (it is the first version Pertronix not the second or third) So, when we got the carb sorted we decided to try the original coil again. The car ran poorly..., fair enough, put the used coil that had worked five minutes prior back in and the car ran poorly again. Not fuel related..., thankfully, ignition. If I pull the coil wire out to the op of the distributor cap, the car seems to run fine. Push it all the way in, crap running... I know it can be a number of issues, coil, points, condenser, wires, etc. Anyone have an opinion off the top of their head? Hemikiller, appears you know these carbs well. i am much more in tune today also... Quite the learning curve for me. They are not a hard carb to work on, but if you don't have the right parts in the rebuild kit, bad news... For the money I paid for this carb in 2016, the guy/rebuilder in New Jersey should have known better...

 

[Hemikiller]

I had no idea about the gasket issue, but since your issue was in the idle circuit, and that's handled mostly in the baseplate, I took an "edumacated" guess. I'm no Q-Jet whiz, but I rebuilt a ton of them back in the 90's when I wrenched for a living. At the time they were mostly the feedback units, but it's still the same basic piece as yours. I used to have a thing for carburetors, probably owned over 100 at one point. I was really good at finding the $5 or $10 carbs at swap meets. Still have a half dozen random model Q-jets on a the shelf if the need strikes.

Just for an FYI, what was the adjustment that needed to be done, maybe a pic or two?

 

[7173Vert]

I had no idea about the gasket issue, but since your issue was in the idle circuit, and that's handled mostly in the baseplate, I took an "edumacated" guess.  I'm no Q-Jet whiz, but I rebuilt a ton of them back in the 90's when I wrenched for a living. At the time they were mostly the feedback units, but it's still the same basic piece as yours. I used to have a thing for carburetors, probably owned over 100 at one point. I was really good at finding the $5 or $10 carbs at swap meets. Still have a half dozen random model Q-jets on a the shelf if the need strikes.

Just for an FYI, what was the adjustment that needed to be done, maybe a pic or two?

Well, you are elevated to Professor in my books... Even a guess like that takes some obvious knowledge of these carbs. I am fortunate to know a guy that like you, knows these carbs well. Even he was stumped for a while, but eventually, you run out of diagnostic possibilities. As an off the cuff remark, I said to him that the two main body gaskets were of a different thickness, why was this the case? That’s when he clued in on the possibility of fuel leaking by internal parts that should be seated. I don’t know the name off hand, but there is a very small adjustment screw in the middle of the base plate at the front of the carb, that normally is set at the factory and plugged. For the power valve seating adjustment? I’m going from memory here... A pic might be hard with the carb back on the engine, but I’ll see if I can get one of the area in question.

 

[TommyK]

I had no idea about the gasket issue, but since your issue was in the idle circuit, and that's handled mostly in the baseplate, I took an "edumacated" guess.  I'm no Q-Jet whiz, but I rebuilt a ton of them back in the 90's when I wrenched for a living. At the time they were mostly the feedback units, but it's still the same basic piece as yours. I used to have a thing for carburetors, probably owned over 100 at one point. I was really good at finding the $5 or $10 carbs at swap meets. Still have a half dozen random model Q-jets on a the shelf if the need strikes.

Just for an FYI, what was the adjustment that needed to be done, maybe a pic or two?

Well, you are elevated to Professor in my books... Even a guess like that takes some obvious knowledge of these carbs. I am fortunate to know a guy that like you, knows these carbs well. Even he was stumped for a while, but eventually, you run out of diagnostic possibilities. As an off the cuff remark, I said to him that the two main body gaskets were of a different thickness, why was this the case? That’s when he clued in on the possibility of fuel leaking by internal parts that should be seated. I don’t know the name off hand, but there is a very small adjustment screw in the middle of the base plate at the front of the carb, that normally is set at the factory and plugged. For the power valve seating adjustment? I’m going from memory here... A pic might be hard with the carb back on the engine, but I’ll see if I can get one of the area in question.

That is the Adjustable Part Throttle screw (APT). It controls how deep in the main jet the rod is set. By raising or lowering the rod in the jet there is a small range of adjustment for part throttle main jet air fuel mixture. It doesn't effect the idle circuit.

 

[7173Vert]

I had no idea about the gasket issue, but since your issue was in the idle circuit, and that's handled mostly in the baseplate, I took an "edumacated" guess.  I'm no Q-Jet whiz, but I rebuilt a ton of them back in the 90's when I wrenched for a living. At the time they were mostly the feedback units, but it's still the same basic piece as yours. I used to have a thing for carburetors, probably owned over 100 at one point. I was really good at finding the $5 or $10 carbs at swap meets. Still have a half dozen random model Q-jets on a the shelf if the need strikes.

Just for an FYI, what was the adjustment that needed to be done, maybe a pic or two?

Well, you are elevated to Professor in my books... Even a guess like that takes some obvious knowledge of these carbs. I am fortunate to know a guy that like you, knows these carbs well. Even he was stumped for a while, but eventually, you run out of diagnostic possibilities. As an off the cuff remark, I said to him that the two main body gaskets were of a different thickness, why was this the case? That’s when he clued in on the possibility of fuel leaking by internal parts that should be seated. I don’t know the name off hand, but there is a very small adjustment screw in the middle of the base plate at the front of the carb, that normally is set at the factory and plugged. For the power valve seating adjustment? I’m going from memory here... A pic might be hard with the carb back on the engine, but I’ll see if I can get one of the area in question.

That is the Adjustable Part Throttle screw (APT). It controls how deep in the main jet the rod is set. By raising or lowering the rod in the jet there is a small range of adjustment for part throttle main jet air fuel mixture. It doesn't effect the idle circuit.

Interesting, I keep hearing that the issues I am having are not repairable via the idle circuit. Yet, the evidence I have seen warrants an investigation between the idle circuit and the throttle (off idle) coming on. Between these two areas, is where my running issues have been. As I am not an expert on these carbs, I certainly will not try and refute any experts opinions here. What I do know, is that the carb is running correctly for the first since I owned it and installed on my engine 2 years ago. Tricky business for sure and I needed another set of eyes to help me overcome the long standing issue with my car. Time will tell, if we are where we need to be with this carb. Thanks for the input.

 

[TommyK]

Well, you are elevated to Professor in my books... Even a guess like that takes some obvious knowledge of these carbs. I am fortunate to know a guy that like you, knows these carbs well. Even he was stumped for a while, but eventually, you run out of diagnostic possibilities. As an off the cuff remark, I said to him that the two main body gaskets were of a different thickness, why was this the case? That’s when he clued in on the possibility of fuel leaking by internal parts that should be seated. I don’t know the name off hand, but there is a very small adjustment screw in the middle of the base plate at the front of the carb, that normally is set at the factory and plugged. For the power valve seating adjustment? I’m going from memory here... A pic might be hard with the carb back on the engine, but I’ll see if I can get one of the area in question.

That is the Adjustable Part Throttle screw (APT). It controls how deep in the main jet the rod is set. By raising or lowering the rod in the jet there is a small range of adjustment for part throttle main jet air fuel mixture. It doesn't effect the idle circuit.

Interesting, I keep hearing that the issues I am having are not repairable via the idle circuit. Yet, the evidence I have seen warrants an investigation between the idle circuit and the throttle (off idle) coming on. Between these two areas, is where my running issues have been. As I am not an expert on these carbs, I certainly will not try and refute any experts opinions here. What I do know, is that the carb is running correctly for the first since I owned it and installed on my engine 2 years ago. Tricky business for sure and I needed another set of eyes to help me overcome the long standing issue with my car. Time will tell, if we are where we need to be with this carb. Thanks for the input.

I am no expert but I ran a Q-jet for several years mostly because I wanted to learn about them. One of the differences between a Q-jet and a Holley style carb is that the Q-jet idle and transition circuits have a much smaller range of influence on part throttle driving. This is because the Q-jet booster is much more sensitive than a Holley main booster and so becomes active earlier at much smaller throttle openings. So when I say that the APT adjustment has no effect on the idle circuit that doesn't mean it has no effect at small throttle openings that would typically be feed by the idle circuit on a Holley carb. Glad you got yours sorted out.

 

[7173Vert]

Oh well, can’t figure out how to get a video uploaded here off an iPhone, so next best thing...







As I had to get the car running properly in order to move out of our current home... and move 45 mins away to our temporary rental home.

After much researching, trial and error, I was able to solve the carburetor issue which allowed for a smooth move with time to spare. Moving this car was the last big piece to go. If anyone comes to Niagara Falls and are interested in seeing the car, look me up... It won’t get any closer to the USA border  It still has yet to be seen and enjoyed in the public eye. 

Well, not quite a totally true statement. As I was towing the car to its new home, a guy in a minivan was following me. Obviously, towing the car on an open trailer has me keeping a close eye on what was transpiring behind me... I could see through my mirrors, the minivan driver moving his one hand side to side and I thought maybe there was an issue with the car on the trailer, so I pulled over... He pulled up along side me and was excited... “Wow, just wow” were his first words... His hand waving in the minivan was simply his excitement at seeing the car. His wife just sat there shaking her head and smiling. Seeing his enjoyment at seeing the car, even on a trailer, reinforces my owning and restoring this car worthwhile