I hooked the vac advance canister to manifold vacuum and gave that a try. It does idle quicker, but it's still not any smoother. I'm beginning to wonder if my problem lies elsewhere, so I'll provide all the details I know.
The heads are flat washer plug heads with 76cc chambers from a 69 chevelle. I'm running R43S plugs, and I checked them today and didn't notice any real discoloration. Maybe a little light, if anything. But they're brand new. 300km on this thing.
It's been a while since I ran a car without a catalytic converter, but is it supposed to smell like a lawn mower?
I read in the manual that came with my cam, not to use late-model timing chain sets. I just ran a basic double roller for a small block Chevy. I don't know if this matters, but I'm mentioning it.
I read online that a low vacuum at idle could indicate either a slight intake manifold leak, or retarded valve timing. Should I start looking in these areas for a solution to my rough idle?
Maybe my valves aren't adjusted right. I tightened them down to zero lash, then 3/4 of a turn past that.
Bad valves maybe? I would have thought that'd be indicated on the vacuum gauge.