[Shiny]

Please help me diagnose and get this fixed efficiently (I'm wordy, so bear with me).

Since rebuilding my carb about 10 years ago, car has been run only intermittently while I worked on stuff at my slug pace. After sitting for maybe a year since last starting, it is now out of sorts.

Car is idling like caca and stinks, which it didn't do when I first put the carb in nor last few times I started it.

I guessed it was crazy rich, so after starting cold today, I noticed the tailpipes had pewed sooty water, which I think is consistent. I held the choke flap open and it ran better, another clue to me it was rich. After it warmed up I turned the idle adjusters in a half turn and got no reaction at all.

So then I looked down the primaries and it looked like the volunteer fire crew had opened the hoses. Check this:

link to video

Does this strategy make sense?

1. try to get it to idle in gear and get RPM down, check for improvement
2. remove mixture screws, blow air in

Any other obvious things to do before I open it up?

If these two things don't fix it, seems next would be:

3. check inlet seat and float level

If that doesn't yield anything obvious I guess it will be time to tear it down and set up again?



Carb is on the original 70 350, 71 manifold, Summit 2800, TH350, mechanical fuel pump.

Carb is:

69 Buick PN 29240MD 0699

Cliff kit
New shaft bushings
Threaded and glued plugs


Modified as:

Primary Jets 070
Primary Rods 041
Secondary rod CE
Drilled holes in secondary feed tubes
Drilled idle tube to 0.037”
Yellow spring

Idle mixture screws had control when I first installed, obviously not happy now.

My guess is inlet not closing.. I think I had a brass float but don't remember.

Thanks for any direction that will save me time.

[Half-Inch Stud]

Drilled Secondary feed tube holes not in my plans, but not the issue with Idle and pull away.

I built 3 Q-JETs a few years ago, and only now started sorting out the (lack of) tune into my low-vacuum 469. Surely we have a common Idle circuit problem. Timing ought be optimized & ruled out.


Observe idle set screw position: Primaries nearly closed, or is it idling on the Primaries?
Focus on idle, and 2000 RPM idle: what does tip-in test indicate?

[johnta1]

I'd say check the float setting?
Probably the float is sticking from sitting.
If it was stuck open it would flood over the vent stack and other things.
So, think it is kind of leaking past needle.
Maybe even just has some crud in it.


Take top off and take a look.

[MUSLCAH]

Send it to Cliff

[beertracker]

Carbs are hard to debug over the keyboard so many variables. A few thoughts.

Since it's spewing fuel out of the primary towers it's wants more air. First thing I would do is open the top and look for dirt\debris.

It may have sucked up tank sediment after sitting for a year. The same thing happened to my q-jet.

Good Luck,
bt

[Cliff R]

Rebuild ten years ago and has sat for a year without being used?

I'd start out by removing the carburetor and giving it a thorough cleaning, and upgrading the internals again, as we have upgraded many of the parts in recent years to hold up in this new fuel. We have a low cost "basic" rebuild kit for your exact scenario, containing new gaskets, high flow Viton N/S assembly and complete pump assembly with lifetime warranty seal on it.......Cliff

[Shiny]

Thanks all

I'll order a new kit and hope the inside hasn't corroded too bad to clean up.

[Shiny]

Kit ordered.

Cliff's High Performance is great to deal with. I called, was told they are working on it now and it will gbe in the mail today!

I get the best advice, best parts, and best service in one call.

Note to self: If you rebuild your carb, let it sit for 10 years, you get to do it again. Hopefully the new parts will get my carb back.

[P@blo]

The video is a little dark but this guy knows his stuff, especially tools. A new perspective sometimes goes a long way.

https://m.youtube.com/watch?v=G0gefXOr1_M#

[Shiny]

Teardown found some particle debris in the carb, but no sign of corrosion, so I'm relieved about the condition of the carb.



I don't have a smoking gun, so have to assume the float was stuck, although it wasn't obvious. I guess it's possible there was no fuel flowing through a clogged idle system and I had opened the primary blades to compensate, but the transition slots were no more than half-exposed. This doesn't make sense to me as the cause of the flooding, but I am ignorant.

I do see the filter got hit with some serious garbage, but it did act like a filter. This was on the filter inlet, but not on the carb side:



The plugs I put in the wells 10 years ago held fine. Bowl holds fuel, no leaks there. Thanks to Cliff's book for that one.

The pump plunger I got from Cliff 10 years ago looks good. Gaskets did not disintegrate. You can see some particulate debris but the blue elastomer looks good. After 10 years, I'd say this part alone is worth the price of the kit:



No obvious issue in the inlet seat or plunger. If there were chunks in there, they leaped out when I opened it up.





I speculate there is some crap flying around in the stale gas in the tank. If there is a rubber hose at the tank, then that may be falling apart.

My plan is to pump the old gas out of the tank, put the carb back together with the new kit, hope the filter and new gas bring the idle back.

I can't afford the time to replace the tank right now.

I might consider adding another filter, depending on what I pump out of the tank.

Does it make sense to crank the motor and let the mechanical pump flush a little before I put the carb back in?

[quizkid32]

Could those particles be charcoal from your vapor canister? Some one on this (or another) forum had that issue.

[Shiny]

Good thought.

Honestly, I don't think my car has a charcoal canister, but as I said, I'm ignorant.

If it did have one, wouldn't it be on a vapor line and not in the fuel line?

My carb has the filter inside the inlet housing. The paper towel was just shoved inside the filter opening and pulled out. I guess it's possible the gasket between the filter and the inlet fitting may have disintegrated. I'll check that.

On that note... as I understand the filter is pressed against the nut and gasket by a spring. If the filter is clogged, the pressure will compress the spring and allow fuel to bypass the filter (like a relief valve). Maybe this is part of the answer?

[TedRamAirII]

Rip the filter apart and see whats in the paper.

[Shiny]

The black stuff came from the paper.

I don't know what it is. Not likely anything related to gas getting old, nor does it look like corrosion products. My guess is a hose, seal, or gasket decided the new gas was too much to deal with.

I bought a cheap pump to empty the tank through the filler neck, but the hose was too short... tomorrow is another day.

[steve25]

Those little black particles are the car's original rubber fuel hoses ( like the one off the sender in the tank ) on the car coming apart due to today's Alky cut gas.
Many times they are small enough to get thru a filter and make for issues like wrong metering or jamming the needle open .

[Shiny]

Thanks Steve

That makes sense.

I don't have time to drop the tank, need the car running to move it until I can do it right.

Is the paper filter in the carb housing good enough for a short time or do I need a better inline filter? If so, what is recommended? I'd rather cut the line before the pump than after.

[SRR]

Wow, you take great pictures!

[Shiny]

Thanks, but it's not me.. the cell phone did it.

Unfortunately, none of the pictures explain exactly why my carb was flooding. I would have preferred to find plugged up tubes or giant chunks of the black stuff inside the carb. So far, all the tubes look clear.

As it is, I can just put it back together with the new kit and hope it works better this time with a new needle and seat, new float, and new filter.

[chiphead]

The red "bathtub ring" in the fuel bowl is rust. The fuel lines and fuel tank need cleaning or replacing. You get some of that hung up between the needle and seat, and you're gonna have a fountain of gas in no time.

[Shiny]

chiphead

yes, makes sense, thanks