the last thing i have yet to perfect in my tune is my timing table, mostly in cruising range.. and im hoping to get some advice

im running a timing table that was made by a tune-by-mail guy for someone with the same cam on a similar engine

the table seems to mimic a distributor with no vac advance; it runs 28 degrees flat up to 2000, where it advances straight up to 35 degrees at 2800rpm. there's no variation in map vs advance in the table at all.

this map is exceptional for hard driving. the thing flies, snaps you back in your seat, and it'll smoke the tires no problem in any gear.

my afr is definitely alright, i've tuned with plug chops and narrowband in driving range.

i've noticed at part throttle high vacuum at lower rpms has a pretty decent surge, and there's a hell of a rough spot around 2200 rpm no matter what the MAP (that might just be rotating imbalance, though) worst of all, it seems like my fuel economy sucks bad for cruising. im almost certain it's a timing thing.

to me, it seems all wrong. the lt1 should be able to handle quite a bit more timing advance, especially at higher vacuum... weird thing is, it seems like any attempt i make to 'improve' the timing table logically in non hard driving ranges (say.. increase advance around 1500-2200 but high vacuum) is met with harsh cam surge, or really laggy throttle, the car 'hates' it.

also idle timing is very tough on this thing, it seems that 20-22 degrees is freaky rough but clean burning....23-25 degrees smooths it out, but almost makes your eyes burn, making my exhaust all misty from the reaction. there's no in between..

so.. any tips?

here's some cam specs:

Advertised Duration (Int/Exh): 262/270
Duration @ .050 (Int/Exh): 211/219
Gross Valve Lift (Int/Exh): .507/.515
LSA/ICL: 112/106

stock compression and all that stuff..