vacuum leak btwen brake booster n master cilinder reason for timming to low
 

i was trying to tune my car with crome, so im ussing p29 so my compression is 245 psi each cylinder, i started with p30 base map but i heard knockin when cruisin btwen 2-2.5k and when i use the a/c the sound comes stronger and the entire band, so i went lowering the timming but its incredible how low i need to go, i start thinking on my map sensor, so i cleaned and recheck the static time, timming belt, etc. and its ok. so its when i went with vaccum lines and i heard a leak and found it btwen brake booster and master cylinder. You think this could be the reason for my knocking? any help i will apreciate.