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882993md

Gasoline dripping out of air intake ports

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Hi everyone,

I got the exhaust finally installed and started the car up for the first time in a year. I removed the air filter so it was easier to work and I noticed that both air intakes were dripping gasoline. 

 Upon closer inspection the backside of the orange air filter housing also had gasoline being deposited on it. Where you see my finger touching is the location the gasoline was dripping down on both from both carbs. I’m guessing the gasoline could be penetrating the gasket on the intake to the orange housing? 

 I checked all the connections and rubber hoses and there were no leaks, however when I wiggled the float bowls they had some movement (I don’t know if that’s normal). 

 I have to tune the carburetors so if the settings are way off, and it’s running rich, would a rich setting account for the abundance of gasoline exiting the intakes?

This is my first experience with carburetor so I really don’t have a knowledge baseline to draw. Any help is appreciated. Thank you.

Howard

1974 260z

 

426CC6F2-EBE8-448B-9D99-BAD97A12A2CC.jpeg

 

Edited by 882993md
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I would guess you've got at least one, maybe two stuck float valves. When a float valve is stuck open, it feeds gas into the air cleaner housing.....just like your picture:wacko:  It's normal for the float chambers to move.

Edited by Diseazd

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 @882993md A rich setting won't account for the fuel in the air filter.  Another possibility is the float levels being set way too high allowing fuel to pool on top of the nozzles. I suggest this because you did start the engine and I'm assuming it ran OK. I don't think it would have run very well with stuck needles. How easy did it it start and how well did it run?

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1 hour ago, Mark Maras said:

 @882993md A rich setting won't account for the fuel in the air filter.  Another possibility is the float levels being set way too high allowing fuel to pool on top of the nozzles. I suggest this because you did start the engine and I'm assuming it ran OK. I don't think it would have run very well with stuck needles. How easy did it it start and how well did it run?

It started fine and ran well. I still have to set timing but it responded well to the throttle revs. I shut it down when I saw the leak as I was afraid of it catching fire.

Howard

Edited by 882993md

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 I'd try the straw first as Cliff suggested first but it sounds like you'll need to remove the float chamber covers and check the needles and seats for foreign matter in them and check the float level. You may need new gaskets for this procedure. There is another way to check float levels without removing the covers. One can remove the suction chambers and pistons, (no gaskets needed, be careful not to bend the mixture needles) look down at the top of the fuel nozzle. The fuel level should be just below (no more than 1/16") the top of the nozzle. I'm betting you'll see fuel above the nozzle. BTW, your nozzles should be about 2 1/2 turns down if the float level is right. Another BTW, the fuel pressure should run about 3 - 3 1/2 pounds of pressure. Much more than that and the pressure can overcome the ability of the needles and seats to shut off the fuel supply to the float chamber.

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I removed the float bowl covers and drained and cleaned the bowls and flow control valves with B-12 Chemtool. I sprayed into the fuel feed tube and turned it over to drain. I did that several times and hopefully that removed any possible sediment in the control valves. I have to replace the cork gaskets as they are falling apart.

I did notice that the pin that secures the float bowl slides without any sort of stop or tension. I don't know if the sides of the bowl prevent the pin from sliding,  or if this is an incorrect pin.

Both choke wire plastic casing are broken (under the dash). I will order some bicycle wire casings to replace from the levers to the carbs.

These are three screw carbs. Is there a standard setting for the float levels, or do I have to locate a model number somewhere on the carb. body for specs?

Howard

carb1.jpg

Float bowl.jpg

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I think that the pins are held in place by the sides of the bowl.  Once assembled they can't get out.

Have you examined the valve itself?  As I recall, they're typically a rubber coated pointy piece that sits in a precision ground hole.  The float presses it in to the hole as it rises.  The rubber can get hard or take a set or have a groove worn in it over time, and not seat properly anymore.

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You put the straw in the wrong hole.  If you'll look, it's too late now though but, the straw in the other bung would hit the top of the float and push it down unsticking a stuck float.  Those pins cannot slide out when the lids are mounted on the float bowls, there's not enough room on either side to slide out.  They will hit the float bowl housing.

When you say broken under the dash do you mean broken under the choke lever on the console?  If that's the case the easiest fix is to buy a choke holder from Art Singer on ebay.   

 

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882993

You are attacking this issue in the proper fashion. I'M IMPRESSED!  These carburettors are really simple. 4 adjustments:

ENRICHMENT CIRCUIT :AKA CHOKE  common on all carburettors especially SU carburettors

BALANCE SCREW: Named for obvious reasons used for synchronization another very simple procedure once you have the proper equipment.

RICHNESS ADJUSTMENT: Once again named for obvious reasons. On our carbs suggest 2.5 turns intially as a baseline adjustment and then fine tune from there.

PROPER FUEL PSI: Often overlooked. Mechanical pumps driven by the engine, electric pumps driven by the battery. Use of a regulator is strongly suggested with electrical pumps. If I am correct, at least in my two, the factory left a connection on the main harness for conversions from mechanical to electric. Plug and play once you locate it.

There are hours of videos on YOUTUBE  that explain tuning our carbs step by step. You can see what moves if the choke is operating properly, how the mixture happens, etc. Being able to see and hear really removed the intimidation factor for me even with triple side drafts. The choke cable sheath if in disrepair will change the travel limit of the enrichment circuit, possibly not allowing full travel even when you have exhausted the travel of the handle on the console. I like your style, NOT AFRAID. Do some more reading and try to put aside time for learning. Get the correct tools so as not to ruin anything. Z Therapy also is a good technical resource. Be patient and good luck.

Edited by esmit208
Misspeling

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