I think you have to keep in mind that Primary WOT fuel is delivered by all four systems, which include the mains and the PV channel restriction. Sooooo, you gotta get that right first.
After that is right........then you can start delaying the PV, until it goes lean when the mains get to full capacity.
I like to bring the PV in as late as possible, without getting into a sag.
If you wanna know where your sag is, just install a vacuum gauge on the intake, swap out the PV for a plug, and go for a roadtest. Get up into second gear and about 2500rpm or stall speed, then start accelerating to a certain vacuum reading. Say 12 inches. Roll into the throttle until you are accellerating at 12 inches and then just hold it there until you get to about whatever rpm your ignition timing is all in, or 3600.
No sag?
Repeat, but, dropping the vacuum to 11 inches.
Sooner or later, the engine is gonna go lean and it will complain about it. Make note of the vacuum reading, and go find a PV with a 1 inch higher rating.
Here's the thing;
If your PMJ is not right, then your PV rating will be Not right either.
If your PMJ is too rich, then your PV can come in later.
If your PMJ is too lean, then the PV will have to come in earlier.
Some guys like to run the PMJ lean for fuel-economy, but that usually creates other problems. If you are concerned with fuel economy, then get the ignition timing worked out instead; you will be way further ahead.
Your best bet is to disable the secondaries, throw a boatload of Vacuum advance timing at it,then get the PMJ figured out. And finally delay the PV, until the engine sags and then back up a hair.
For example;
My 367 runs 32/34 Power Timing at 3200/3400, with alloy heads. More timing does not make it any quicker. The Idle timing is 14* and I run a two-step centrifugal curve that switches at 2800, where the timing starts at 28*. And this timing allows me to burn 87E10 gas at 11/1 Scr and up to 185 psi, jus saying.
But my Vcan brings in 22*, and it is all in by 12.5inches vacuum. So at 2800rpm, my Cruise timing could be as high as 50* or as low as 28* depending on the manifold vacuum.
Ok so suppose at 2800 and cruising, my vacuum is 18 inches, and timing is 50*. So I can slam the pedal down until the vacuum drops to 12.5 inches with NO Loss of timing.
Now, my PV is timed to start delivering fuel at 10.5. . But the Vcan has only dropped out a couple of degrees, so the engine is still pulling hard. The harder I step on it, the lower the vacuum drops which causes the Vcan to smoothly and rapidly drop timing out to prevent detonation, while simultaneously the PV begins delivering ever more fuel.
This all happens automatically, and the car surges smoothly ahead.
I like it a lot, and I think everybody should experience this because I gotta tell ya, when you get your 360 working like this, you will love it, and it will be hard to wipe the grin off your face. Now add a Thermoquad, and you will get addicted to the roar,lol.
