Captain Obvious

You think you're boiling fuel even with a 30 psi rail? So where exactly is it that you think the fuel boils? And do you think it's boiling a little at a time on each injector pulse and blowing only vapor into the manifold, or do you think it's sustained and bubbling back into the rail as FastWoman described? One thing that's completely clear from all of this discussion is that with my carbureted Z, I'm simply screwed... And not that it really matters, but I'm still unclear on why you're bringing the concept of superheating into this... You really don't even need it to support the beliefs under discussion. But in any event, it doesn't detract, it's just probably unnecessary.

STP has nothing to do with this. It's all about vapor pressure at elevated temps. You're nowhere near STP. Also, your use of the term "superheated" has become is a little confusing to me, so it might be prudent to make sure we're talking the same thing... What's your understanding of "superheated"?

Yeah, You're right. I probably should have said "the upper limit on vapor pressure is supposed to be tightly controlled" Research indicates that the intention of the gov't is to reduce the amount of fuel evaporation into the atmosphere as much as possible while still allowing the fuel to work well in application. The way they do this is to dictate an upper limit on the vapor pressure for different locations at different times of the year. How the manufacturers achieve that vapor pressure limit seems to be mostly up to them, including the composition and ethanol content of the fuel. My research turned up two things that always seem to be true: 1) Winter fuel (RFG) is allowed to have a higher vapor pressure than summer fuel, and... 2) California requires a lower vapor pressure than most other states. Of course they are. You remember the difference between "suspensions" and "solutions", don't you? And you mentioned the concept of superheat earlier and I forgot to ask... Why do you think the fuel in the injectors is superheated? Seems difficult to achieve. Have we strayed far enough from the OP's question yet?

I did a little digging into the vapor pressure of gasoline and learned that the petroleum industry and US government have standardized on the "Reid Vapor Pressure (RVP)" test. It specifies a test temperature of 100C and measures the resultant vapor pressure in psi. The vapor pressure is constrained by government regulations and is tightly controlled by industry. The limits change by location and time of year, but from what I found, the vapor pressure of your typical pump gas (at the RVP test temperature of 100 degrees C) is between 5 psi and 11 psi depending on where you live and what season it is. Vapor pressure will decrease as temp goes down and go higher as the temp increases. So how hot do the fuel get and what pressure is it under? Being as how I'm not an ME, it's probably not a good idea to wade into the middle between two of them, but I've never been very bright...:tapemouth

jaltman, Just sent you a PM RE the 73 airbox. Captain

I'm unclear how worn carb parts could increase the oil consumption. The damper oil is nowhere near the venturi and it seems that any worn parts should only make the situation better, not worse. That's more like what I'm thinking... The only way (you should be able) to get oil out of the plunger tube would be to pull it up and out the top. Maybe the plunger check valve disk is in backwards or something? desertmonkey, Did you ever disassemble the brass pieces off the stalk?

That's weird... There isn't supposed to be any way for the damper oil to drain out of the suction piston. Does it go alll the way empty if you don't refill it? Or does it reach a point and level off and stop dropping?

PM back achoo.

Rob, Wow... Talk about coincidence... I've got one that I was going to scrap because the casting is all eaten away and corroded under the EGR valve. If you're positive that you'll never actually want to use it on a car, it's perfect for practice. It's probably off a 77 if that matters. Yours for $1 plus shipping if you want it. PM me offline if you're interested.

Thanks Blue! :beer:That's some great info there. Answered my question, and a few others that I had not even asked (yet)!

Blue, I assume the outer is the one on the left? Does the inner have a seal on the other (hidden) side as well?