Need More Vacuum

Do you know the correct procedure? If not, I'll let you know....if you do, just ignore this. lol Block the drive wheels really good. Set the parking brake hard. Find the small angled vacuum outled in front of the carb on the base plate. That's manifold vacuum. Hook your gauge there. Strat the engine and bring it up to temp. Drop it in drive. Adjust the idle mixture screws until you acheive the highest reading on the vacuum gauge. I usually go a half turn leaner and call it done. You're bout runnin outta tuning things that can cause this. Rockers having the lifters pinned down with too much preload would be in the back of my mind.....but try the carb and see what happens.