Slant Six Forum
https://slantsix.org/forum/

Real irritating carb leak problem
https://slantsix.org/forum/viewtopic.php?t=3028		 Page 1 of 1
Author:  James Lawrence [ Sun Dec 23, 2001 3:53 pm ]
Post subject:  Real irritating carb leak problem
I have a 73 dodge dart sport. It came with the 1bbl holley. I took super six parts of a volare some years ago and put them on. It ran great for years. 1 year ago I developed a bad problem where gas would come out around the base of the carb and trickle down. Engine would not idle when it was doing this. I rebuilt the carb including a new float. It still did it. I re-rebuilt the carb...it still did it. I replaced the carb with one of those (holley?) remanufactured carter type carbs. It ran great for 6 months and bam! The problem is back. Gas is seeping out everywhere around the base of the carb. This new carb was preset and I haven't touched a thing inside. It had been running better than I've ever had with the rebuilt carb when it was working properly. I can't figure out why this is happening. Float ok and set right. Needle and seat also.... Now a new carb and it has developed the same problem. New fuel pump and filter where installed when the first carb started this problem.

Anybody seen these very popular 70's super 6 and 318 v8 carbs have this problem???

I desperately need help. This carb set me back near 200 bux. I don't want to buy another.

spldart@yahoo.com
Author:  Peter [ Sun Dec 23, 2001 4:39 pm ]
Post subject:  Re: Real irritating carb leak problem
Quote:
: I have a 73 dodge dart sport. It came with the
: 1bbl holley. I took super six parts of a
: volare some years ago and put them on. It
: ran great for years. 1 year ago I developed
: a bad problem where gas would come out
: around the base of the carb and trickle
: down. Engine would not idle when it was
: doing this. I rebuilt the carb including a
: new float. It still did it. I re-rebuilt the
: carb...it still did it. I replaced the carb
: with one of those (holley?) remanufactured
: carter type carbs. It ran great for 6 months
: and bam! The problem is back. Gas is seeping
: out everywhere around the base of the carb.
: This new carb was preset and I haven't
: touched a thing inside. It had been running
: better than I've ever had with the rebuilt
: carb when it was working properly. I can't
: figure out why this is happening. Float ok
: and set right. Needle and seat also.... Now
: a new carb and it has developed the same
: problem. New fuel pump and filter where
: installed when the first carb started this
: problem.
:
: Anybody seen these very popular 70's super 6
: and 318 v8 carbs have this problem???
:
: I desperately need help. This carb set me back
: near 200 bux. I don't want to buy another.


I once had a similar problem. Turned out to be a new fuel pump with 12 psi. Fuel pump pressure should be about 5 psi. I would check this pressure just to be sure.Good Luck.

pgonsi@optonline.net
Author:  James Lawrence [ Sun Dec 23, 2001 7:30 pm ]
Post subject:  Re: Real irritating carb leak problem
Quote:
: I once had a similar problem. Turned out to be
: a new fuel pump with 12 psi. Fuel pump
: pressure should be about 5 psi. I would
: check this pressure just to be sure.Good
: Luck.


Thanks. That's the third thing I checked last time...first float, second needle seat. Then I put in a new pump and finally resorted to pressure test. But it still acted up. :( Any other ideas guys? I'm stumped and I've stumped both of the best racer/builder guys I know.


spldart@yahoo.com
Author:  GLS [ Sun Dec 23, 2001 8:03 pm ]
Post subject:  Re: Real irritating carb leak problem
Quote:
: I have a 73 dodge dart sport. It came with the
: 1bbl holley. I took super six parts of a
: volare some years ago and put them on. It
: ran great for years. 1 year ago I developed
: a bad problem where gas would come out
: around the base of the carb and trickle
: down. Engine would not idle when it was
: doing this. I rebuilt the carb including a
: new float. It still did it. I re-rebuilt the
: carb...it still did it. I replaced the carb
: with one of those (holley?) remanufactured
: carter type carbs. It ran great for 6 months
: and bam! The problem is back. Gas is seeping
: out everywhere around the base of the carb.
: This new carb was preset and I haven't
: touched a thing inside. It had been running
: better than I've ever had with the rebuilt
: carb when it was working properly. I can't
: figure out why this is happening. Float ok
: and set right. Needle and seat also.... Now
: a new carb and it has developed the same
: problem. New fuel pump and filter where
: installed when the first carb started this
: problem.
:
: Anybody seen these very popular 70's super 6
: and 318 v8 carbs have this problem???


We're talking about a Carter BBD Carb? I want to confirm this before I call up a friend of mine that should have the answer. It may take a couple of days before I can reach him (due to the Holiday season) but I should have something for you soon. I know that the throttle plate shaft on the BBD will wear and allow fuel to 'leak' past. That may be what has happened. I've had one rebuilt where a brass insert and o-ring were installed which solved the problem (at least as long as I had the car).

Hope you have a great Holiday!

Gotta Love Slants!
Tim

tmoore722@aol.com
Author:  Doctor Dodge (Doug Dutra) [ Sun Dec 23, 2001 11:05 pm ]
Post subject:  Re: Real irritating carb leak problem
Quote:
: I once had a similar problem. Turned out to be
: a new fuel pump with 12 psi. Fuel pump
: pressure should be about 5 psi. I would
: check this pressure just to be sure.


Excess fuel pressure at the needle / seat after shut-off can cause fuel to leak through the carb. Do you have a vapor return system?

A worn throttle shaft, incorrect carb base gasket, leaking needle / seat
or a plugged return system can cause this problem.

A fuel pressue / vapor return line may help.
Also make sure the throttle return spring is in line with the carb. and not to tight
DD
Author:  James Lawrence [ Mon Dec 24, 2001 1:42 am ]
Post subject:  Re: Real irritating carb leak problem
Yes. A Carter BBD. This new carb was rebuilt/built well by my best judgement. There is no play whatsover in the throttle shaft bushins.
Quote:
:
: We're talking about a Carter BBD Carb? I want
: to confirm this before I call up a friend of
: mine that should have the answer. It may
: take a couple of days before I can reach him
: (due to the Holiday season) but I should
: have something for you soon. I know that the
: throttle plate shaft on the BBD will wear
: and allow fuel to 'leak' past. That may be
: what has happened. I've had one rebuilt
: where a brass insert and o-ring were
: installed which solved the problem (at least
: as long as I had the car).
:
: Hope you have a great Holiday!
:
: Gotta Love Slants!
: Tim



spldart@yahoo.com
Author:  James Lawrence [ Mon Dec 24, 2001 2:04 am ]
Post subject:  Re: Real irritating carb leak problem
Fuel leak is excessive and only during operation.
EGR and Cannister emmissions systems are disabled.
PCV is active. Vacumm advance is active and the valve operated heated air system is active.
The old carb had excessive play in throttle shaft.
New carb is tight.
Both exhibited this problem.
Gone through 4 base gaskets of 2 different varieties.
Quote:
:
: Excess fuel pressure at the needle / seat after
: shut-off can cause fuel to leak through the
: carb. Do you have a vapor return system?
:
: A worn throttle shaft, incorrect carb base
: gasket, leaking needle / seat
: or a plugged return system can cause this
: problem.
:
: A fuel pressue / vapor return line may help.
: Also make sure the throttle return spring is in
: line with the carb. and not to tight
: DD



spldart@yahoo.com
Author:  Doctor Dodge (Doug Dutra) [ Mon Dec 24, 2001 8:43 am ]
Post subject:  Re: Real irritating leak problem
Quote:
: I have a 73 dodge dart sport. It came with the
: 1bbl holley. I took super six parts of a
: volare some years ago and put them on. It
: ran great for years. 1 year ago I developed
: a bad problem where gas would come out
: around the base of the carb and trickle
: down. Engine would not idle when it was
: doing this. I rebuilt the carb including a
: new float. It still did it. I re-rebuilt the
: carb...it still did it. I replaced the carb
: with one of those (holley?) remanufactured
: carter type carbs. It ran great for 6 months
: and bam! The problem is back. Gas is seeping
: out everywhere around the base of the carb.
: This new carb was preset and I haven't
: touched a thing inside. It had been running
: better than I've ever had with the rebuilt
: carb when it was working properly. I can't
: figure out why this is happening. Float ok
: and set right. Needle and seat also.... Now
: a new carb and it has developed the same
: problem.
:
: I desperately need help. This carb set me back
: near 200 bux. I don't want to buy another.


The key to fixing a leak is to first understand exactly where it is comming from. If it is leaking a lot, it should be easy to trace.

In general, there are 3 areas to be concerned with:

Pressure Side: everything including the needle seat.

Fuel bowl & holding areas: Carters are easy with the one piece bowl casting, Holley's have more places to leak. Always inspect the "swedged-in" plugs on the carb body.

Venturi area: the worn throttle shaft or a bad base gasket are examples of this but Venturi leaks usually run after shut-off and become vacuum leaks when running.

Get everything real clean, dry and have a bright light handy, find out exactly where that fuel is comming from, I do not feel it is the base gasket, I think it is leaking somewhere else and running down to that spot.
DD
Author:  James Lawrence [ Mon Dec 24, 2001 3:34 pm ]
Post subject:  Update
Ok. Fuel pressure was ok. Throttle shaft ok...Well, everything seemed ok.

I unplugged the unused cannister and bowl vent fittings after I stayed away from the problem for quite a while. (also to allow the carb and manifold to dry out.) And it started perfect. Like a new motor! Cold, one pump and crank with no depression of the gas pedal. Hot, depress gas pedal a tad and crank. It's firing easy :-o. No gas leaks so far. And now the idle circuit adjustments work again. It was so rich before it wouldnt adjust. So I set those adjustments and idle speed and take it for a drive. ALL the power is back. (I had some burnt valves I had replaced too)

Thanks for your help.

spldart@yahoo.com
Author:  James Lawrence [ Fri Dec 28, 2001 7:24 pm ]
Post subject:  Re: Update
Well...It's been a week and no leaks :)
Between the head work (bad valves) and getting the carb undercontrol my fuel economy has gone from an in city average of 11mpg to 20mpg. This is Houston driving with lots of stop and go traffic. I can't wait to see if my freeway mileage is back up to the 30 range I was toying with some years ago :)
Now I (just to be nitpicky) have to chase out this ever so slight hesitation the carb (i think it's the carb) has when trasitioning from the idle circuit to the mains. I think it might be going a tiny bit to lean just as I'm first cracking the throttle.

spldart@yahoo.com
Page 1 of 1 All times are UTC-08:00
Powered by phpBB® Forum Software © phpBB Limited
https://www.phpbb.com/