I'll go through he trouble of doing a compression test,but shouldn't need to. the head was rebuilt,2 years,and about 600 miles ago. I had hardened seats installed. When I had it apart,there was no cylinder ridge,in any of the 6. Engine does not smoke,even at start-up. I REALLY think I have a vacuum leak,just haven't found it yet. The "BB" in the accelerator pump discharge is lodged,(Rochester B),and won't come out. Is that the location of the "low speed jet"?I know I installed the right one,when the carb was first completely rebuilt,2-years ago. Just might be time to replace it?? Thanks!