Something doesn't seem right.
a. Engine not effected by blocking PCV. It should have dropped or increased in rpm and vac.
b. Fuel pressure swinging at idle. That seems like a lot of swing for idling. See what others say. Its been a few years since I've had a gage on - my memory is fuzzy on this.
c. The idle mix screws having a large effect on off-idle driving. They should have a large effect on idle and small effect on off-idle. Percentage wise, the fuel should be coming through the least restrictive path - the transfer slots.
Closing the IABs:
Getting these blocked with my fingers isn't an easy task. The choke plate is in the way. And the IABs have screwdriver slots where they can still pull some air with the finger on top. But: When I put my fingers on them the rpm goes down a bit. Not much, but you can hear it.
This is interesting. Doesn't want richer.
Turning in the idle mixture screws:
My setting was 1 turn out on each of the four screws. Closing one pair (doesn't seem to matter which one, pri or sec) half a turn would make the engine slightly rev up.
Wants a little leaner - at least with no load on it.
Turning in the second pair of screws brings revs down again. Screwing them further into the seat (one pair, the other is still half turn out) would make the engine run very rough. Closing all screws kills the engine.
So they do seem to be working.
I left it at 1 turn each and did some part throttle driving. Once I am rolling the AFR goes to the rich side, AFR around 13.0.
On a cam like that, vacuum goes up when opening throttle from closed. The greater pressure difference, the more flow, up to around 14"Hg when it chokes.
I found a good setting of blades and mixture screws with my current IFRs and IABs. Car drives very well and doesn't seem to have flat spots. No off idle bog.
I am running out of ideas. Checked a lot of stuff, all seems to be as it should. Agree?
If you got it where you like it, then that's good.
