Holley 4160 explanation

[Xavi3r]

Hi guys !

i need some explanation on a holley 4160 carb that is on a 1970 monaco 440.
the car was running waell until last week. it run rough, has a crush on acceleration..

we are trying to understand the functionement of the carb. the main quesion is about the vent valve that apears to be related to anything.
Can you explain me the role of this valve and how it works ?

here the carb ( he is a bi rough to me ) :

and other side : ( can you tell me why there is a vacuum diaphragm and a heat choke together ? )

we found a burned wire to : can it explain the car running rough ( it is the ground for the coil I presume )

 

[70bigblockdodge]

Vent valve only at idle. '68 vents to atmosphere, 70 vents to tank with California emissions.
I think it was to eliminate vapors in air cleaner housing to clean up idle emissions.
Those original equipment Holley's are warpage prone. Which leads to internal leakage problems. They are mediocre at best.
The vacuum pot is the choke pull off, cracks the choke plate open once engine starts. The big one is for the vacuum secondaries.