Carb Leak?

[SaxMan]

Whenever I do my post-drive inspections on Baby Blue, I had noticed some wispy smoke coming from where the throttle shaft is held in on the forward carburetor, just below the vacuum line attachment. I didn't think much of it, and figured is was oil burning off, although there was no detectable smell to the smoke. Now, when I drive, particularly with the top up, I'm definitely picking up a gasoline odor. I'm fairly certain it is coming from forward, as the gas tank and fittings were replaced last year, and my nose seems to be telling me it's coming from up front. I'm wondering if one of the rubber parts or the chamber gasket is leaking and dropping minute amounts of gas and if what I'm smelling is related to the wispy smoke I had seen earlier.

I was going to keep Baby Blue going until the first snow or New Years, but I'm thinking if I have a gasoline leak to deal with, maybe it's time to take the car off the road to address the matter before the leak becomes bad enough to cause a fire.

 

[dklawson]

Are you using H or HS series carbs?

 

[nomad]

Is the gasket on the float bowl cover in good shape? Sounds like that could be your culprit.

Kurt.

 

[SaxMan]

These are HS2s if I'm correct ('69 Sprite Mark IV). I'm thinking pinhole leak in the float bowl is a possibility. I can certainly open up the bowls and see what kind of shape the gaskets are in.

 

[dklawson]

Check the condition of the float valves and their seats in the bowl lids. While there, make sure the float level is set correctly. With the lid removed, the gas should fill 1/2 to 2/3 of the bowl. The bowl lid gasket serves only as a seal to prevent gas from sloshing out during cornering. If you find gas is oozing out of the bowl lid gasket, that suggests the float level is set too high.

Also do what you can to keep as much of the fuel hose below the level of the bowl lids. If a lot of hose is routed "high" above the bowl lids, that fuel will slowly drain into the bowls while the car is parked if there is any leakage past the float valves.

 

[SaxMan]

Poked around tonight and found the screws on the forward float chamber had loosened up slightly. It also looks like the line that runs from one float chamber to the other could probably use replacement. The line is a bit swollen and dry on the forward chamber and the braiding is frayed as it gets to the rear chamber.

 

[nomad]

Should be able to turn on the switch and wait till the pump pushes some fuel out to find out if its leaking at a junction or fitting.

Kurt.

 

[SaxMan]

I took the car out today. Gas smell was far more attenuated than it had been previously, so I think I'm on the right track. Now I need to quiet down an exhaust leak, either where the manifold hits the pipe, or the manifold to the cylinder head. I'm hoping the manifold itself isn't leaking.

 

[SaxMan]

Manifold bolts had worked their way loose. Cranked them down and the car was much quieter! I think I still have one at the junction between the exhaust pipe and muffler. Will crank that one down, too.

Beautiful day with temps near 70 degrees gave me another opportunity for a top down cruise. Out on the rural back roads, I tripped across another driver in some kind of vintage Eurpoean coupe - it looked E-Type-ish, but was a bit wider and the taillights were higher up the body and had otherwise no identifying trim, maybe a Kellison Corvette, but doubtful. He was putting his car through the paces and I happily tacked myself onto his car. He would easily out accelerate me, but the Sprite was outcornering him through every curve. It really gave me an opportunity to see how good the Sprite was among its contemporaries. I really wanted to stay with him and see exactly what he was driving, but I had to make my turn to get back to civilization.