Carb leaking through primary shaft on shutdown???

[Super Blue 72]

Hi guys!  A little leaky issue going on.    Thanks in advance for any suggestions! 


Ok, '72 340, stock Thermoquad.  Initial start is fine.  Noticed on shut down, warmed up all the way or just run for a little while, there's gas dripping out the carb on the passenger side of the carb from the primary shaft, a good drip every 3-4 seconds.  Makes for a little hard restart.  Assumed it's from fuel dumping in the carb after shut down.   

Is this possibly from a needle for the float not closing off all the way?  Primart shaft worn?  I figured it wasn't the shaft because even if the shaft was worn the carb shouldn't have gas dumping like that. 

What is the best/least invasive remedy for this?  Am I looking at a carb rebuild? 

Thanks a bunch! 

Phil 

[Chryco Psycho]

sounds like 2 problems to me
1 - your float setting could be too high
or
2 - you do not have the heat crossover blocked under the intake & the exhaust heat is boiling the fuel in the carb causing it to overflow the boosters & sit on the throttle plates & leak through the shaft

[Super Blue 72]

Thanks for the reply, Neil. 

As far as the float goes, I rebuilt the carb back in about 2004.  The problem just recently (As far as I know) started.  Is the float adjustable without taking the carb apart? 

As far as the heat cross over, the engine has never been taken apart, still has the factory intake on it.  Is the heat crossover OPEN or Blocked from the factory?  I assume that it is open from the factory.  Also, the issue arises with the leak even after only startin gthe engine for just a couple of minutes, not getting to warmed up temperature.  That's why I was wondering if the needle is not seating or something....

 

[vinb]

Get a rebuilding kit,
 Standard/Hygrade kit #657C & two float's #FL4.
Take it apart and go thru it that way you know everything is right, also check the center bowl were the jet wells are, the epoxy may have loosen or broken off.
A good epoxy that Manley or JB weld make will do the trick...

[72rtchallenger]

sounds like the float,,you can take the top of the carb off while its on the motor,,if i remember correctly there is a float on each side of the carb,,as you say its leaking only on one side,,and if your fuel tank is original,it may have sucked up some rust and caused you this problem

[Chryco Psycho]

you have to remove the top of the carb to set the float height

[Super Blue 72]

Whatcha doin' awake, Neil?       You're always tirelessly helping out here!  Much appreciated!   
 It's 4:18am eastern US time here.  I fell asleep putting the kids to bed, woke up at about 1am to clean up the kitchen and do some laundry then worked on a '63 Ford Fairlane 427 Thunderbolt 1/24th scale model.  Giving it to a friend for his birthday. 

Anyhows, thanks for the help guys!  It looks like I'm going to pull the carb and rebuild it again.  I did change the tank last year.  Maybe it did loosen up some rust/sediment and it's doing something evil in the carb.  I'll check the #s on the carb kit and floats too against the ones listed to make sure I get the right ones from the parts store.

Thanks again guys!  You guys are always there for me! 

[Chryco Psycho]

 
 I don`t run on a normal clock for sure , just don`t call me in the morning 

[Super Blue 72]

 I don`t run on a normal clock for sure , just don`t call me in the morning 

    That's why PM's are good, they don't make any noise!!! 

[Chryco Psycho]

TRUE

[hooD]

Super Blue 72 .....
My TQ is doing almost the same thing.  It leaks at both sides at the bottom shaft.  It has never been rebuilt.  Restarting a warm/hot engine is always embarrassing because it is flooded.  I know gas dumping into the engine is not good for the oil. 

A local engine shop told me that he thought my carb was "peculating" the fuel and that the TQ carb in general is a piece of crap.  He said to go with a holley or an edelbrock carb.  I can order a rebuilt TQ from autozone for $200 but I'm not sure which way to go.

[Chryco Psycho]

by comparison the TQ is actually a very good carb If it is in good condition , the Eddy carbs are Junk & have virtually no adjustments .
 I would pull the intake & block the heat crossover port under the carb to limit the heat under the carb as a solution to stop the fuel boiling/ perculating inside the carb

[hooD]

by comparison the TQ is actually a very good carb If it is in good condition , the Eddy carbs are Junk & have virtually no adjustments .
 I would pull the intake & block the heat crossover port under the carb to limit the heat under the carb as a solution to stop the fuel boiling/ perculating inside the carb

If I were to pull the intake, what would the heat crossover port look like and what is used to block it?

As far as the TQ goes, I would rather keep it and have it rebuilt.  Who around here rebuilds them and where can you find a kit?  I don't know if I have the nerve to rebuild the carb without messing it up.

[Super Blue 72]

Thanks for the info guys! 

Rebuilding a carb isn't rocket science although you do need to be organized.  When I rebuilt my carb about 5 years ago, I got it from Autozone for about $20.  Worse that could happen is that you are out $20 or so.  If it doesn't work out, then you can get someone to rebuild it.  If it does, pat yourself on the back. 

In general, I like the theory behind the resin body (what was the name for it, phenolic?) for cooling the fuel and the smaller primaries for economy.  I'm going to stay with the TQ for now since my engine is still stock.  I hope a rebuild will fix the issue.  The engine doesn't have to be warmed up for the dripping to happen when I shut down the engine.  The heat crossover does make sense if the problem occurs hot.   

[Chryco Psycho]

the heat crossover port is the center port in the head , cut a piece out of the old intake gasket to cover the hole on both sides