Re: 69 350 Running rough in gear
Try plugging the vacuum advance hose into manifold vacuum if it's not already connected to that. (Of course, cap off any hose nipple left unused when doing this.) Also, check carefully for vacuum leaks. Check all hoses, make sure the carburetor baseplate gasket is not leaking, etc. A good way to do this is to spray carburetor cleaner around the base of the carburetor while the engine is running. Try to ensure the spray doesn't get sucked into the air intake snorkel on the air cleaner housing, and see if the engine speed changes when you spray. If it does, you've found a vacuum leak.
'71 chevelle, 468, TH400, 12 bolt posi w/3.08's, drinks a lot of 87 octane.