ive been trying to fix this for a month now.
basically, it only happens when braking. for example, your slowing down for a stop sign, you brake harder, clutch is in, the revs drop to about 500 rpm. you stop, it goes to 350 rpm.
when you give it throttle at that state, it hesitates and the throttle response is crap until it rises to its normal idle.
or when it drops to 350 rpm and you dont touch the gas at all, it goes up,down,up,down(by barely anything, than it rises up to about 1200 rpm, you tap the gas, it goes to its normal idle.
the headlights dim, the steering wheel almost locks up and the car almost dies, only while braking.
it doesnt matter if you gear down and hold it in 1st at full stop, or you put it in neutral and just brake. it does the same thing.
i had my carb tuned twice to address this. timing has been advanced, and retarded, nothing. put my battery hold down clamp on. tightened my drivebelt tension, replaced the fuel pump about 6 months ago. the mechanics say its not my carb or float level. also if this makes any diff my alternator bracket is missing about 3 bolts but it feels solid while not running. (1 is busted in the water pump, and i just havent gotten around to the other 2 yet.
what is going on? any ideas???

btw, thanks for reading this long post.

 

Vacuum leak in the brake booster? How's the brake pedal feel?

 

brake pedal feels good. i replaced the white valve that goes into a grommet in the brake booster, but i havent replaced the "dryer valve?"(as i was told) between that and the carb

 

It's not a "dryer valve", whatever that would be, it's a check valve to keep vacuum in the booster when the manifold vacuum is low.

 

do you thing i should replace that check valve?
i was thinking it was either a fuel delivery issue or something in the charging system

 

and why would my manifold vacuum be low when i brake?

 

I don't know if the check valve itself would be your problem. It's there to keep vacuum in the booster when vacuum is low, such as at WOT or if the engine stalls. I've also heard it prevents fuel and oil vapours from attacking the diaphragm in the booster.

You might have a leaking booster. Try disconnecting and plugging the vacuum line to the booster and see if the problem goes away. You might not want to drive it like that. You'll have to be careful if you do. The pedal will be hard, you'll have no power assist on the brakes.

 

With the car off about 10 minutes or so you can check for reserve. Should be able to press the brakes easily at least 2 times. If you can't then I"d look at the booster.