Hey fellow stangers!
I have been having a beast of a time getting my vacuum advance to work. It causes instant backfire unless idling. I'm running a holley 570 street avenger though my 670 avenger did the same. I have the crane cams adjustable vacuum advance cannister on a 76 granada distributor with mech and vac advance and steel gear. Full mechanical advance is in at 36 degrees by 2500 rpms with 14 base. Car has factory cam and pulls a happy 21 hg at idle. Oddly it pulls 21 hg with the mixture screws bottomed out and it wont run more than a coghing chokey stalley 300-400 rpm with idle screw topped out and ignores idle screw otherwise. The spark port pulls like 6 hg idling and rises with neutral rpm to 25-30 at higher rpms. When given decent maybe 2/3 throttle in gear it drops to 12-10 hg but I have never seen it drop to nothing. I dont dare floor it. This is vacuum advance disconnected since car wont do anything other than idle with spark port connected to dizzy. When connected, the timing goes it 40 or so. When ANY throttle is added, the timing mark shoots somewhere else (off scale) and the engine backfires. I am aiming the timing light while giving it some throttle by hand. It does this timing zoom weather the crane adjustable vacuum advance cannister is bottomed one way or the other. Vacuum cannister adjuster with allen wrench bottoms clockwise and "clicks" after a while counterclockwise. That doesnt seem right. Should "bottom" both ways and one of the extremes should cancel all vacuum advance, right? I have taken the vacuum advance hose and sucked on it with about 2 hg (I vacuum guaged myself =P ) and produced zero advance so the spring in there IS resisting at least a bit.
So I suspect both units. Any thoughts gentlemen? Are those numbers correct?
I have been having a beast of a time getting my vacuum advance to work. It causes instant backfire unless idling. I'm running a holley 570 street avenger though my 670 avenger did the same. I have the crane cams adjustable vacuum advance cannister on a 76 granada distributor with mech and vac advance and steel gear. Full mechanical advance is in at 36 degrees by 2500 rpms with 14 base. Car has factory cam and pulls a happy 21 hg at idle. Oddly it pulls 21 hg with the mixture screws bottomed out and it wont run more than a coghing chokey stalley 300-400 rpm with idle screw topped out and ignores idle screw otherwise. The spark port pulls like 6 hg idling and rises with neutral rpm to 25-30 at higher rpms. When given decent maybe 2/3 throttle in gear it drops to 12-10 hg but I have never seen it drop to nothing. I dont dare floor it. This is vacuum advance disconnected since car wont do anything other than idle with spark port connected to dizzy. When connected, the timing goes it 40 or so. When ANY throttle is added, the timing mark shoots somewhere else (off scale) and the engine backfires. I am aiming the timing light while giving it some throttle by hand. It does this timing zoom weather the crane adjustable vacuum advance cannister is bottomed one way or the other. Vacuum cannister adjuster with allen wrench bottoms clockwise and "clicks" after a while counterclockwise. That doesnt seem right. Should "bottom" both ways and one of the extremes should cancel all vacuum advance, right? I have taken the vacuum advance hose and sucked on it with about 2 hg (I vacuum guaged myself =P ) and produced zero advance so the spring in there IS resisting at least a bit.
So I suspect both units. Any thoughts gentlemen? Are those numbers correct?
