1955 running rich

[zeroroadkill]

Any way to lean a Teapot 4000 other than smaller jets? I believe I’m running.050 jets. I’m sure the stock tune is for sea level. I’m at 2500’ and seem to recall you should advance the timing 1/2° for every 1000’, Is this true?

Had a fuel starvation incident yesterday on a 90° day. I’m thinking it was vapor lock so I ordered a fuel line insulation wrap to see if it helps. Once she started to stumble and I pumped the accelerator and slowed to 40mph and the stumble stopped. The next time I floored it and she finally stopped stumbling and took off after a few seconds. Engine running about 80% on temperature gauge.

FYI: New gas tank, new fuel lines, new electric fuel pump (bypassing mechanical pump) new fuel filter bowl and filter (all clean, no debris, fuel bowl full) new carburetor screen filter, resent carburetor overhaul (Mike’s carburetor), non-ethanol fuel, vented gas cap.

Will pull a spark plug and check for fouling.

Doug, any suggestions?

Thanks

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[cokefirst]

Unless someone has messed with the jets on an original carburetor that is not likely to be the problem. I found that the vacuum operated stem that opens the power valve can be faulty leaving the power valve open all the time. That was the cause of my rich mixture. You could also have a float that is too high or a faulty needle and seat. With all the bad rep these carbs get, they actually run pretty nice when properly rebuilt and tuned.

 

[doug7740]

Any way to lean a Teapot 4000 other than smaller jets? I believe I’m running.050 jets. I’m sure the stock tune is for sea level. I’m at 2500’ and seem to recall you should advance the timing 1/2° for every 1000’, Is this true?

Had a fuel starvation incident yesterday on a 90° day. I’m thinking it was vapor lock so I ordered a fuel line insulation wrap to see if it helps. Once she started to stumble and I pumped the accelerator and slowed to 40mph and the stumble stopped. The next time I floored it and she finally stopped stumbling and took off after a few seconds. Engine running about 80% on temperature gauge.

FYI: New gas tank, new fuel lines, new electric fuel pump (bypassing mechanical pump) new fuel filter bowl and filter (all clean, no debris, fuel bowl full) new carburetor screen filter, resent carburetor overhaul (Mike’s carburetor), non-ethanol fuel, vented gas cap.

Will pull a spark plug and check for fouling.

Doug, any suggestions?

Thanks

I have read many posts to vapor locking and remedies to cure it, mostly having to do with insulating or cooling the line from the mechanical fuel pump to the carburetor. Everything has been tried from aluminum foil to wooden close pins. None of the cures seem to be effective, I believe, because that line is not the problem.

Vapor Lock appears to be a term used to describe either the stalling of the engine or poor performance of the engine due to a lack of fuel to the engine. I am convinced that the stalling or otherwise poor performance of the engine may be due to a fuel deficiency, but the deficiency has nothing to do with the temperature of the line running from the fuel pump to the carburetor assuming that the stock, metal fuel line is used and routed as per design and the fuel pump is operating per design.

As I view it, in normal operation, the vented fuel bowl on the carburetor is kept full of fuel by the needle and seat, controlled by the float. As the float drops it allows gas into the bowl. If for some reason the gas in the fuel line between the pump and carburetor became heated hot enough to vaporize the fuel, the vaporized fuel would be admitted into the fuel bowl and be vented out of the fuel bowl.

Gasoline boils somewhere between 100 F and 400 F at atmospheric pressure depending upon the additives used. At 4 psi the boiling point would be in the upper range, much hotter than under the hood of an operating vehicle. Meanwhile the fuel pump, pumping at about 4 psi would push new, cooler fuel through the line into the fuel bowl and thus feed the engine and cool the line and the carburetor. Therefore it is hard for me to see how a car under operation would suffer from vapor lock due to the heating of this line. I have observed poor performance (rough running, stalling) of an overheated engine, but it had nothing to do with vapor lock and everything to do with the engine getting tight due to the heat.

Where I think “vapor Lock” could occur is upstream of the fuel pump. If for example the gas tank was not properly vented, or there was an obstruction in the fuel line between the fuel pump and the fuel tank. The fuel pump would now reduce the pressure in the fuel line and reduce the fuel’s boiling point. Now any increase of the temperature (fuel line too close to an exhaust pipe) of the line running to the fuel pump could cause a vapor to form preventing the pump from pulling fuel into the pump and sending it along to the carburetor.

In conclusion, if my car suffered from “Vapor lock” I would be looking for a faulty fuel pump (low output pressure or volume), a faulty vented gas cap, a leak in the gas line up stream of the pump, or an obstruction up stream of the pump.

doug7740
1955 Thunderbird Blue

 

[zeroroadkill]

Thanks Doug, I forgot to mention that the first instance was after climbing a long uphill grade at 60 mph an on a 90° day then as I was descending she started bucking and actually coughing, which sounded like backfiring. The same thing happened the second time on level ground at about 55 mph. I do not have the factory float gauge but I think I read somewhere it’s 1/4 inch from the top of the case???

 

[zeroroadkill]

Unless someone has messed with the jets on an original carburetor that is not likely to be the problem. I found that the vacuum operated stem that opens the power valve can be faulty leaving the power valve open all the time. That was the cause of my rich mixture. You could also have a float that is too high or a faulty needle and seat. With all the bad rep these carbs get, they actually run pretty nice when properly rebuilt and tuned.

Do you mean by the vacuum operated stem that opens the power valve the economizer diaphragm?

And since I don’t have the factory float gauge, I think I read somewhere it’s 1/4 inch below the top of the fuel bowl casing?