Carb Advice

[j340lm]

I have a 1970 Dart Swinger 340 that I'm trying to get back on the road for cruise-ins. Have the car 54 years, know it inside and out. Has not be on the street since about 2008. Age and health issues are limiting the work on I can do to get it ready. Found that when I trickle some fuel down the carb it seeps out past a rod/bushing. The carb is old and rebuilt once a Holley 0-80454 600cfm. The recomended replacement Holley is a universal 80457S 600 cfm, electric choke. Not a fan of the chrome ones that are available but the dichromate finish ones are twice the cost new if found. The motor is an original 340, with the old school Edelbrock LD-340 manifold and I replaced the dual-point dist to electronic years ago. Trans is a 727 Torqueflite with a Direct Connection Shift Kit. Fuel is a mix of Sunoco Standard Race Lead (110 oct) and Pure Gas no ethenol (93 oct). Mix is due to the original valves in the heads. Does not like to start easy sometimes after sitting several weeks and will idle in park but gets iffy when put in gear. Pretty sure the carb should be replaced to start with because of the location of the leak, plus don't want fuel on a hot manifold even though it does not seep when running. Any suggestions? Next step is to find someone who has the knowledge to work on these classics. I'm not talking about a Condads, Mr Tire, NTB or the other chains. Thanks. (The overall pic is from the last cruise in '08). UPDATE the secondary shaft (red outline) has play in it when compared to the old ones. Also checked the throtle shaft and there is very slight play, not as much as the secondary one.

 

[Professor Fate]

Sounds like your throttle shafts are worn out and need to be rebushed- is there any up-and-down or back-and-forth movement to the shafts? Worn throttle shafts would explain the fuel drips, and when running is just a big vacuum leak- which may be part of your idle issues.
Instead of replacing, consider sending it off to be rebushed/rebuilt by a reputable carb rebuilder; for instance Woodruff Carburetor Specialties, a member here and a site sponsor. Plus, he's sort of local to you... Contact info is at the top of the sidebar-->
If you were happy with the carb when it was functioning well, I see no reason to replace it with a new one (possibly of dubious quality and probably questionable price...) and have to go through the whole tuning/setup process all over again.

 

[RustyRatRod]

That's a fairly new looking carburetor to have worn throttle shaft holes, but that sure sounds like what it is. A lot of times that's caused by too much throttle return spring(s), but it appears you have one that's not a monster, so that might not be it.

 

[TrailBeast]

I have a 1970 Dart Swinger 340 that I'm trying to get back on the road for cruise-ins. Have the car 54 years, know it inside and out. Has not be on the street since about 2008. Age and health issues are limiting the work on I can do to get it ready. Found that when I trickle some fuel down the carb it seeps out past a rod/bushing. The carb is old and rebuilt once a Holley 0-80454 600cfm. The recomended replacement Holley is a universal 80457S 600 cfm, electric choke. Not a fan of the chrome ones that are available but the dichromate finish ones are twice the cost new if found. The motor is an original 340, with the old school Edelbrock LD-340 manifold and I replaced the dual-point dist to electronic years ago. Trans is a 727 Torqueflite with a Direct Connection Shift Kit. Fuel is a mix of Sunoco Standard Race Lead (110 oct) and Pure Gas no ethenol (93 oct). Mix is due to the original valves in the heads. Does not like to start easy sometimes after sitting several weeks and will idle in park but gets iffy when put in gear. Pretty sure the carb should be replaced to start with because of the location of the leak, plus don't want fuel on a hot manifold even though it does not seep when running. Any suggestions? Next step is to find someone who has the knowledge to work on these classics. I'm not talking about a Condads, Mr Tire, NTB or the other chains. Thanks. (The overall pic is from the last cruise in '08).

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Hoping you know that most any carb can leak at the shafts if pour fuel in it.
That fuel lands on closed throttle plates making fuel seep out the shaft.
Shafts are not air tight, and it doesn’t leak when running because there is a vacuum there normally.

 

[OldmanRick]

Hoping you know that most any carb can leak at the shafts if pour fuel in it.
That fuel lands on closed throttle plates making fuel seep out the shaft.
Shafts are not air tight, and it doesn’t leak when running because there is a vacuum there normally.

I agree.

Since your running quality fuel, have you looked into advancing the timing a bit. That may cure your starting and idle issues.

 

[j340lm]

Hoping you know that most any carb can leak at the shafts if pour fuel in it.
That fuel lands on closed throttle plates making fuel seep out the shaft.
Shafts are not air tight, and it doesn’t leak when running because there is a vacuum there normally.

It was just a brief slight trickle I did. Not like some of the guys on tv who pour gas in while cranking it. The car did eventually start with some starting fluid. So it will run.

 

[AJ/FormS]

IMO, not a big deal.
Get your Transfers set-up right and it'll probably run fine.

 

[j340lm]

That's a fairly new looking carburetor to have worn throttle shaft holes, but that sure sounds like what it is. A lot of times that's caused by too much throttle return spring(s), but it appears you have one that's not a monster, so that might not be it.

Age wise its close to 20+ years old. Back in 20146 I used Sunoco 94 mixed with Cam II and stored it w/o starting it for about 4 months. That was the first time I had the carb rebuilt by a corner garage guy who claimed he knew how to rebuild them. I knew ethenol damaged the rubber but he only used a partial rebuild kit. I thought it would be completely disassembled, soaked, cleaned and all components of the Holley rebuild kit were to be used. Never really worked correctly after that rebuild. Woodruff Carb is roughly 100 miles SE of me, I'll give them a call and FedEx over to them. Rather rebuld it correctly tahn taking a chance on a new chrome plated one. Thanks.

 

[RustyRatRod]

Age wise its close to 20+ years old. Back in 20146 I used Sunoco 94 mixed with Cam II and stored it w/o starting it for about 4 months. That was the first time I had the carb rebuilt by a corner garage guy who claimed he knew how to rebuild them. I knew ethenol damaged the rubber but he only used a partial rebuild kit. I thought it would be completely disassembled, soaked, cleaned and all components of the Holley rebuild kit were to be used. Never really worked correctly after that rebuild. Woodruff Carb is roughly 100 miles SE of me, I'll give them a call and FedEx over to them. Rather rebuld it correctly tahn taking a chance on a new chrome plated one. Thanks.

Woodruff can do all of it, throttle base bushings too, I believe. Heard nothing but good things.

 

[Demonracer]

Before you jump off and spend money unnecessarily, at idle squirt carb cleaner or brake clean at the shaft. If the rpms go up you have potential shaft leakage. Diagnose first, spend money second.

 

[j par]

My new build with new carburetor doesn't start easy when it sets over a week ...
If I put a squirt of gas in the carb it fires right off...
Thinking about a electric fuel pump by pass for starts or go down the money trail and do fuel injection witch is also an electric fuel pump...

 

[j340lm]

Sounds like your throttle shafts are worn out and need to be rebushed- is there any up-and-down or back-and-forth movement to the shafts? Worn throttle shafts would explain the fuel drips, and when running is just a big vacuum leak- which may be part of your idle issues.
Instead of replacing, consider sending it off to be rebushed/rebuilt by a reputable carb rebuilder; for instance Woodruff Carburetor Specialties, a member here and a site sponsor. Plus, he's sort of local to you... Contact info is at the top of the sidebar-->
If you were happy with the carb when it was functioning well, I see no reason to replace it with a new one (possibly of dubious quality and probably questionable price...) and have to go through the whole tuning/setup process all over again.

There is play in the secondary shaft, more than the throttle shaft rod. Today I sprayed some carb cleaner at the seconday shaft and the motor stalled out. I repeated it on the throttle shaft area and the motor rpm reduced and would have also stalled had I kept spraying. This sound like I finally identified the problem?

 

[j340lm]

Before you jump off and spend money unnecessarily, at idle squirt carb cleaner or brake clean at the shaft. If the rpms go up you have potential shaft leakage. Diagnose first, spend money second.

It stalls out when I spray the secondary shaft and the rpm drops when I spray thethrottle shaft area.

 

[OldmanRick]

How far out are your idle mixture screws. A decent tuned Holley should be no more then 1 1/2 to 1 3/4 out max. If out more then two, you surely have a air leak somewhere near the baseplate.

And as i said earlier, make sure your running enough initial timing.

 

[Bewy]

All carbs have some shaft play.....for safety so that the throttles do not bind in the open position.
It would be odd that the sec shaft is worn more than the pri because obviously the primaries get more use...