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Hey guys, so I’m running a mild 350 with smog heads in my 72. Just redid most of the ignition system (new coil, MSD box, rebuilt my MSD pro-billet distributor). I put in 12 degrees of initial timing and 23 degrees mechanical...so 35 total.
I set the idle mixture on my 670cfm Holley street avenger using a vacuum gauge, and I’m pulling a solid 16” of vacuum at idle (14 in gear). No needle fluctuation whatsoever.
So here’s my question: is there a way for me to diagnose a lean condition/detonation using a vacuum gauge while driving? I have this mild but noticeable vibration/roughness at around 2200-2500 rpm under light/medium throttle. But at WOT the engine doesn’t vibrate and seems to pull nicely. Or could I be having an entirely unrelated issue? :rolleyes:
If it helps, I’m using the two blue (light) springs in my MSD distributor.
 
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