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leaking carter bbd
https://slantsix.org/forum/viewtopic.php?t=7548		 Page 1 of 1
Author:  pantseatflyer [ Fri Nov 14, 2003 7:23 am ]
Post subject:  leaking carter bbd
going through a mood swing right now. I was so excited last night after mounting my rebuilt carb and starting it up. It sounded really good.

but this morning I was checking it out in daylight and noticed a fuel leak around the base, as well as a slow drip from the throttle shaft. The base I figure just needed to be tightened to better seal the gasket, but what about that drip? Is that bad news?

Oh yeah, I also removed the air cleaner so I could get at the pcv hose and clamp it. After I put the cleaner back on it wouldn't start! I checked the hoses to make sure I didn't knock one off when I was messing with the cleaner, but they all looked to be attached. What the heck?! Why won't it start now? Flooded perhaps?

To recap:
1. Leaking around the throttle shaft - what's that all about?
2. Wouldn't start after removing the air cleaner and clamping the pcv hose - flooded or ??

Help me, please.
Author:  Guest [ Fri Nov 14, 2003 8:28 am ]
Post subject: 
#2 you an forget, there really is no possible way by taking the aircleaner off (unless its lean-burn wich yours is not) that you can affect starting your vehicle.

my guesses on the BBD are:

1) your missing a check ball inside the carb (either for accelerator pumpshot) or for your boosters
2) the base isnt tightend down to the main body of the carb
3)incorrect float adjustment (this normally causes a leak between the mainbody and the upperbody of the carb tho)
4)your metering rods arnt in the jets and just lying beside (doubt it but its happend before)

time to taker back apart again ;). its ok, its a learning process :)

Justin
Author:  pantseatflyer [ Fri Nov 14, 2003 8:46 am ]
Post subject: 
Quote:
#2 you an forget, there really is no possible way by taking the aircleaner off (unless its lean-burn wich yours is not) that you can affect starting your vehicle.

my guesses on the BBD are:

1) your missing a check ball inside the carb (either for accelerator pumpshot) or for your boosters
2) the base isnt tightend down to the main body of the carb
3)incorrect float adjustment (this normally causes a leak between the mainbody and the upperbody of the carb tho)
4)your metering rods arnt in the jets and just lying beside (doubt it but its happend before)

time to taker back apart again ;). its ok, its a learning process :)

Justin
thanks for the suggestions, Justin.

1) I know both balls are in there because after I rebuilt it, I second guessed myself and took it apart just to make sure I had them both in.

2) tightening everything down could be it. Like I said, I didn't have it bolted on tight enough to the intake because I saw gas leaking. But what about the throttle shaft dripping? That's coming out of the shaft, right? I read about this carburetor having problems with wear around the shaft area. Could it be worn?

3) The float adjustment I double-checked just like those two balls. In fact, I broke the original float because I couldn't get it adjusted just right. I bought a new float and feel confident that I have it adjusted properly. But you never know...

4) The rods are definitely in the jets. I spent a lot of time in that area, so I'm sure about that.

But I still don't get why it wouldn't start back up. It started fine this morning and idled just fine. It wasn't until I turned it off to add that clamp to the the pcv hose that it wouldn't start back up. That's also when I noticed the fuel leak at the base.

I'll try starting it again tonight. You're probably right that I'll end up taking the carb apart again. If I do, should I get another kit for the gaskets now that these have been compressed? Will this never end?
Author:  Doctor Dodge [ Fri Nov 14, 2003 10:54 am ]
Post subject: 
Fuel dripping from the throttle shaft tells me two things:
1) The throttle shaft area in the carb body is worn.
2) Excess fuel is flowing into the carb / engine after shut-off.

The worn shaft is hard to fix so I would focus on why fuel flow is still happening after shut down.

A high float level will do this. Todays gas will expand a lot and even boil in the fuel bowl, then spill into the engine to make it hard to restart. Try lowering the floats, 1/16 lower then the spec calls-out.

The needle valve should also be checked. The needle valve needs to hold back 3-5 lbs of fuel pressure after shut-off. The smallest piece of dirt or any inperfection in the brass seat or hard rubber tip will allow that fuel to "slip by" the needle valve and that will overflow the carb., this floods the engine and makes it hard to restart.

On many of my cars I add a pressure bleed-off / return line so the "head pressure" on the needle valve is releived shortly after engine shut down.

My guess is that the engine will restart later, after it "drys-out".
As a test, next time you shut the engine off, remove the air cleaner and look down into the carb, you should not see any raw fuel flowing into the venturi area after the engine is turned-off.
DD
Author:  pantseatflyer [ Fri Nov 14, 2003 11:48 am ]
Post subject: 
It was, after all, the float adjustment that gave me the most challenge during the rebuild. I just couldn't get it right according to the adjustment specs, plus get the lip at 90% vertical to the needle. I kept removing it, bending it, checking it, bending it again until I broke it! Then I had to get a new one.

I'll check for gas after shut off, as you advised. Looks like Saturday will find me back inside the carburetor! Thanks for the info.
Author:  pantseatflyer [ Fri Nov 14, 2003 11:53 am ]
Post subject: 
Quote:
On many of my cars I add a pressure bleed-off / return line so the "head pressure" on the needle valve is releived shortly after engine shut down.
DD
Was this a home made addition? How was it hooked up?
Author:  Doctor Dodge [ Sat Nov 15, 2003 8:33 am ]
Post subject: 
Quote:
Quote:
On many of my cars I add a pressure bleed-off / return line so the "head pressure" on the needle valve is releived shortly after engine shut down.
DD
Was this a home made addition? How was it hooked up?
Yes, this is a "added" fuel return and there are a couple of different ways you can do this.

The best way is to run a new piece of "hard line" (metal tubing) back to the fuel tank. I install a small hose fitting into the filler neck to dump the fuel back into the tank.
Up at the engine, I use a late model fuel filter with a vapor return port, this is a small hose "bib" coming out the side of the fuel filter. I hook the other end of the return line to this new outlet.

The other way the pressure bleed can be done is inside the fuel pump.
If your fuel pump is the type that can be dis-assembled, (Carter type)
then you can drill a small bleed hole between the low and high pressure sides of the pump. Keep the hole small, .020 is all you need. (I use a larger drill to go most of the way, then break through with the small "micro drill")

Either way, when the engines stops, all the extra fuel pressure pushing on the needle / seat is bled-off so that fuel does not overflow into the carb / engine.
DD
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