To start us off, here is the history of this diagnosis.

Here is the original thread, which had the initial story, symptoms, and early diagnosis. This thread let to me tearing apart the front end of the engine to get at the timing chain.
http://forums.corvetteforum.com/c3-t...stic-help.html

This is the second attempt at diagnosing the problem. I replaced the timing chain, which didn't fix things.
http://forums.corvetteforum.com/c3-t...post1583141739

That led to a divergent thread dealing with doing compression test, during which I diagnosed a dead battery being the cause of low compression results.
http://forums.corvetteforum.com/c3-g...ting-a-c3.html

Then back to the Diagnostics II thread, where I went through my entire ignition system.

So, so far in this attempt at fixing my car, I've learned how to replace a timing chain, including how to install and remove a harmonic balancer, oil pan, timing cover, and all the belts. I've removed valve covers and learned the relationship between the valves and the camshaft. I've looked up into the bottom end of the engine without the oilpan on and learned how the crankshaft moves the pistons. I've removed a distributor, disassembled it, and rebuilt it using a small parts kit, which taught me how the tach works, and how the timing related to the crankshaft. I've (sort of) learned the electronics behind a points ignition system. I've learned how to change spark plugs, check timing, change points and a condenser... I feel like I've taken an entire automotive course in the past couple months.

So now that we're caught up...

When trying to start the car once the ignition system was fixed and the timing was set, I couldn't get the car to start. It would crank and crank, and every once in a while a quiet chuff of haze would come out the top of the carburetor, but the engine wouldn't catch. I took a look at the carburetor, and the gasket appears to be wet - soaked through. I open the upper plates in the carb, and more haze comes out of the secondaries. I open the upper and lower throttle plates and shine a flashlight down into the carb, and I can see a puddle of gas sitting on the intake. The interior of the carb is also wet. Ok, so I'm majorly flooding. I undo all the linkages and take the carb off the car. I'm not very familiar with the quadrajet, or any carburetor, but I did partially disassemble it once before, so I work on memory and do the same thing again.

I get down to the float bowl, and I see this sitting down in the bowl:



Now, I could be wrong here , but I seem to recall that this piece is important, and does something, and should not be sitting down in the float bowl. Here is another shot of it once I fished it out:



Could it be? Could this tiny, tiny piece be the cause of all the problems I've been having? If so, I will be LMAO with all the headaches this has caused me. If not, well, let me know so I can get a full rebuild kit for this carburetor. Actually, I might just get one anyway.

 

that is supposed to connect the float to the needle valve, was there any fuel in the bowl when you took it back apart?

 

The bowl was full best I can tell. There was gas spilling out of the carb as I was flipping it my hands to disassemble it. By the time I got down to the float bowl there was only a 1/4" or so left in it.

 

that little clip connects the float to the needle, when the level in the bowl gets low, it pulls the needle valve open which allows fuel to refill the bowl, it's a good bet that you were starving the motor for gas. despite popular opinion, the pressure of the pump will not always push the needle open to refill the bowl

 

The wet carb and puddle of gas in the intake doesn't really lend itself to a diagnosis of fuel starvation. Maybe this clip wasn't the cause.

 

The thing would start without a carb as long as there is a puddle of gas in the intake. I wouldnt think that is the starting problem . Probably 180 out of time.

 

Put it back togather and try it.

 

I agree that part looks like the clip that keeps the needle on the float, but it seems to me that its more about keeping it together during assembly. If anything it would lift the needle when the float drops. Worst case scenario is that the needle wouldn't raise when the fuel goes down in the bowl and you would have a fuel starvation problem which clearly you don't have. I think you're looking at another problem. My best guess is you're not getting spark. Either not strong enough or not timed properly. Possibly the rotor is out of phase, or the wires aren't routed correctly, but I'm betting ignition problem. If you've got compression, and you obviously have fuel, its got to be spark.

 

First, you may be right about the distributor being off - it's not 180* out, but it appears to be 90* out, which may be a mistake I made when I rebuilt it. I'll investigate as soon as I have time.

Back to the carburetor, I think I may have found another piece to the puzzle. I decided to put the carburetor back together with the pin and see if magically that fixed things. The first piece I go to reassemble is the needle seat. I screw it in, but when I go to tighten it down it just spins around and around. I unscrew it, and this is what I find:



It looks like all the threads on the carb end of the fiting are stripped, and it looks like it's corrosion that did it. I took off the fuel filter nut and shone a light down in there, and this is what I found:



There appears to be corrosion of some sort in this end of the fuel path as well.

If the seat wasn't seating, and just spinning in place, that means there was no seal with the gasket, and plenty of room for fuel to be leaking past the threads, The needle wasn't doing anything, so fuel was constantly pouring into the bowl, and it was probably overfilling, which caused the flooding, correct?

Also, what could cause this, and more importantly, is there any way to fix it? I'm really hoping this doesn't spell the end of the carb, but I'm not seeing a way around it. The needle seat itself is in fine condition - looks almost new.

 

If the needle and seat are failing to control the fuel coming into the carb you should see fuel flowing freely down the throat of the primaries due to over filling. So yes if that is failing to seal then flooding would ensue.
Your carb is not necessarily toast. I think some epoxy might fix your problem. Marine tek, If memory serves, is the stuff to use. Lars would know for sure. Epoxy hole a bit, just fill the threads a little and run a tap in once it's dried to put some threads in. A little bubba but would probably work.

http://www.marinetex.com/marinetexepoxyputty.html

http://www.marinetex.com/Marine-Texf...r-Marine-44867

 

I found this product:



http://quadrajetparts.com/rochester-...ads-p-209.html

And am thinking of giving that a try, since I don't own a tap and die set, a heli coil installation kit, or have easy access to a machine shop. Have any of you had success or failure with these types of fixes?

 

Good find. Looks like it should do the job to me. Drill carefully it looks like a snug fit and a nice round hole may be important.

 

I DO have a drill press. It may be 60 years old, but it's solid. I'll line it all up straight and clamp it down.

 

Information directly from Lars on this issue:

I'm leaning towards sending the carb to Lars now to see if it can be saved.

 

For me it would depend on how much that repair would cost and how much I plan on using the car. A replacement used carb can be had on e-bay for $30-$50.
If it were mine I would probably try the marine tek first. Just dab some into the threads make sure you have a new seal and then screw a new seat in. It looks like some of the threads are still there. Don't try to go real tight just enough to contact the seal in the bottom. Should this fail then look to other options. I always try to go from easiest/cheapest but functional repair to hareder more expensive if needed. This is not a structural or safety related component so I would be willing to experiment.
That Q-jet will still run only so-so unless your willing to put some time into it anyhow.
I used this book to rebuild mine plus $100 for a performance rebuild kit from Cliff's web site. The results are phenomenal. You won't regret doing it and learning a bit about tuning that carb for best peformance.

http://www.amazon.com/Rebuild-Modify.../dp/1932494189

 

I was running the numbers, and with the book ($15) the rebuild kit ($80), the carb cleaning dip ($20), and the Marine-Tek ($60), I'm at $175 to have a carb in which I've permanently welded the needle seat, and might not run that great when I'm done. I also might need to buy a couple drill bits. If I mess it up, or it fails in the future, I need a new carb at another $30 minimum, and possibly another $80 for a rebuild kit to make it right. Total could be $285 to over $300.

With Lars I'm at $190 for a guaranteed rebuild, plus $50 for a permanent fix to the needle seat, and $30 for shipping. Total is $270.

Add to that the car has been sitting since early last summer, and once spring hits I'll have a property honey-do that's likely to take up most of my weekends - this route just seems like the best idea for now.

My uncle has half a dozen quadrajets sitting on his shelves at his house in CA. When I have the time to learn how carbs work, and want to rebuild one, I'll get one of those from him, and buy the books, and learn away. I really do want to know it myself, but now is not the time.

 

I can follow your logic. Sounds good.

 

Sent the carb off to Lars this morning for a rebuild. I'll let you know the results in a few weeks!

 

Given what I've heard of Lars's work, you won't regret that decision.