Gasoline in my TH400 shift modulator hose?

[Mrturner1]

Well it's been one little thing after another recently and I have another mystery to solve, however, these little kinks have been getting worked out and in the meantime I've been daily driving.....yes you read that correctly lol daily driving my old truck finally. And I gotta tell ya, it is a truly gratifying feeling. AND! I'm happy to report that these last few little hiccups are NOT a product of my "fixing" things that ain't broke they are just the last of the wrinkles getting ironed out.

So this time I'm totally stumped, but hopefully you guys have some idea of what's going on here. For those that don't know the truck, it's a 1970 C10 LWB, 10.3:1 SBC and has a TH400, as well as a Holley 750 double pumper, manual choke carb. The trans shifting is run by a vacuum operated shift modulator, and that has a fairly large vacuum hose running from the passenger side of the transmission, all the way up to the carburetor, and on my particular application I plugged it into the back of the carb because that's the biggest vacuum port the Holley carb has.

I came across this issue because I got a shiney new trans dipstick, and when I removed the old one I knocked the vacuum hose off of the shift modulator, and a little bit of gasoline came out of it. This is my first Holley carb so I'm still learning the ins and outs, but I don't know what to make of this. The vacuum hose plugs into the carb, but why would gasoline be passing through down to the transmission? I have noticed that when idling, it's very very rich smelling and seems to be bad enough that it pisses people off at stop lights because eyes are burning every which way, and folks don't like that

So far I have only changed the jets in the carb, and adjusted the idle air/fuel mixture screws. Other than that it's all factory. Jets are 73/80, squirters are the factory .031" I believe (or .31" can't remember), the pump cam hasn't been touched, I'm not sure exactly what that changes, nor do I know what the different colored springs do. The power valve is the factory 6.5, and again I'm not sure what changing that would do. My buddy at the speed shop says to measure vacuum with a gauge, and divide that number by 2 and that's your power valve but I haven't tried yet for lack of a vacuum gauge and motivation. I picked up a 4.5 power valve just in case, but I'm not sure if a smaller number (like 4.5 compared to 6.5) makes the valve come in sooner or later. I think the power valve is one of the first things to address because of I'm understanding my reading correctly, it can affect the idle circuit which seems to be my problem regarding watering eyes at stop lights.

So what do you make of the gas in the shift modulator vac hose? It was about 2 teaspoons worth of that makes a difference. Also, the truck feels strong and runs great all the time so I figured it can't be a blown PV or bad carb gasket.

Matt