This started about 2 months ago, was driving at night, crossing a 4 lane road making a left turn. They were paving, but didnt have many signs up and it was raining so I make the turn at like 3 (its a wide turn) anyway the middle 2 lanes were paved already, making them about 2" higher than the rest of the road.

So I hit a 2" vertical at 30mph (see sig for suspension mods)
nasty nasty bump and my engine stuttered a little then seemed ok, so I kept driving. About 5 miles down the road i went to pass someone, shifted into 3rd and put the pedal to the floor, lots of noise, no go at all.

So a few days later I readjusted the carb, just idle and mixture and played with the timing a little. It seemed ok, but it was a ittle random, sometimes it would pull great and other times it would ping and have no power, or just have no power.

So i figured the carb would need to be rebuilt. Dont have money or time to do that so i put it off.

Last weekend I got a rental car to take a road trip with my girlfriend, left my interior lights on and when i came back the battery was dead, and my starter decided to die (it was on its way out).

So as i am installing the new starter in a sand parking lot I notice a vacuum bell hanging off a lever on the exhaust. it seemed to operate a flap within the pipe (I have no idea what this is) it had a broken metal bracket and no vacuum line attached so i just uncliped the C clip and took it off.

New starter, new battery blah everything is working fine.
while I was checking my oil the other day I noticed a hissing sound... so im looking around and i see a plastic vacuum T missing one of the hoses. i trace it toward the block and it runs into the top of the intake manifold, I didnt bother tracing it in the other direction. I put my finger over it and the RPMS dropped about 200 and it started idling smooth. So i put a vacuum plug on it and the car is back to normal again.

So now it all makes sense, that nasty bump broke the metal bracket on the vacuum bell and when that fell it snapped part of the plastic vacuum T off, I am assuming the hose connected to the bell came loose or got caught on something and fell off.
So the carb was never the problem... thing that baffles me is that I didnt hear the vaccum leak right away, it was really loud. =\

Anyway long story, without much point, but does anyone know what that vacuum bell is or does?

 

Its official name is Early Fuel Evaporation (EFE). For all the years before emissions became such an issue, we called it the "heat riser valve".

It is a valve that closes off the right head pipe, by way of a vacuum-operated valve. Its purpose is to force the right bank exhaust to flow over the top of the engine, through the passages under the carb, when the coolant is below some preset temp, controlled by a thermal vacuum switch on the water outlet. This heats up the intake and helps the fuel to vaporize better sooner during a cold start-up. Obviously it hurts WOT performance, since it heats up the intake charge.

 

Ok so would I be correct i thinking that the missing vacuum line that I found was hooked to that?

 

It's possible