I have been data logging with Tunerpro RT and Datamaster, and I realized that at idle I have a Kpa around 45, but on level ground cruising at around 1500 to 1700 RPM it's more like 33-38 Kpa. Shouldn't my idle vacuum be higher than any part throttle unless I'm engine braking?? Does that mean I need more timing? It also seems that at light cruise it pulls then lags then pulls and so on. I don't have a giant cam (224/230) and it has 114* LSA, but I do have a stealth ram intake that I have heard needs a lot of timing. I just don't want to bump it up and risk damaging my engine. Any insight would be most appreciated. My engine is a basically stock 350 crate engine with the mentioned Comp Cam, prted Summit Heads with 202/160 valves, and 1.5 roller rockers. I'm using a painless harness with a 1227730 ECM.

 

Lower vacuum at idle than part-throttle cruise is perfectly normal and acceptable for many larger than stock cams. Even the stock peanut cam in my 305 would pull more vacuum at a light load, part-throttle cruise than it did at idle.

 

very normal. The bigger the cam you start running the more pronounced this will become.
I used to run a flat tappet solid cam in my big block camaro that gave me about 4.5 inches of vacuum at 800 RPM idle and jump to about 15 inches at 1200-1400 rpm. A real nightmare getting the powervalve to work right in the holley carb I was using. Of course thats with a 106 degree LC and 250degrees @.050(.615 lift i think).
Anyhow your situation is perfectly normal You'll just have tune for it is all.

 

When it feels like someone is pulling the car back and letting it go while cruising does it mean you need more advance? I'm using a stock timing table for an iron head 350.