I am wondering what others with a mild NA 540 see for vacuum while at idle. I'm seeing 10-11 inches of vacuum. This is low per stock standards but not sure about my engine. 540CI, 9.2-1 Compression, Dart single plane intake with Crane full roller setup. Thanks.

I'm no pro, but IIRC your cam will dictate the amount of vacuum an engine will see. Lift, duration, LSA and valve overlap will all play a big part in how much vacuum an engine will produce.

I'm pretty sure mine were similar to that. Then they blew up

It would help if you posed the cam specs,

camshaft specs vs engine cid, ignition timing, intake manifold (dual vs single vs tunnel ram), and idle rpm are your largest contributors to intake vacuum.

I wish I had the cam specs. Bought the boat from someone that has no idea what they had.

That sucks,

Both my 580 solid rollers fairly heavily cammed are 10" at idle. 260's-270's .700 plus lift.

and then if your carb/s are out of whack,remember adjusting idle while watching the vacuum gauge for the highest reading.

Thanks, seems like mine is mostly normal.