I have an interesting update to my fuel delivery concerns on my wagon. So, lets recap a tad...'62 LandBarge, warm 428, stock (5/16"?) fuel lines from tank to pump, Carter M6905 Pump, large canister style fuel filter on the front of the block, modified 800 Qjet. I finally got an AEM 0-15psig sensor plumbed into my fuel line right in front of the fuel inlet to carb and took a short trip out on the road. Previously I was trying to use a 30psia sensor and the granularity between pressures just was too wide for fuel on a carb...it was difficult to see where the pressure was and where the "noise" in the signal was. Using my LM-2 I was able to drive this sensor and record the data coming back along with an analog pickup of the RPMs direct from the coil and the AFR of course from the wideband 02 in the exhaust. What I had happening, particularly in warm weather was when on a quarter mile pass the motor would fall on it's face above 4000rpm in each gear fairly regularly. Today it was maybe 35 degrees, quite cold and the carb was running consequently quite leaner than usual. It was doubtful it would really fall on it's face as usual, but hit the record button on the LM-2 and made a pass through the first two gears and partially through the third. I was more curious what the M6905 was doing at higher rpm, as I suspected it was losing pressure..and it turns out my suspicions were confirmed.
The graph attached shows a few different things. In magenta is the AFR, which I'd not pay too much attention to, other than in second gear when the fuel pressure really dives the AFR is trending lean. The rpms in black clearly show the shift points between 1-2, 2-3 and then 3-4 and a drop off the throttle.
In red is the voltage coming back from the sensor. I've not yet figured out how reprogram the graph for this with a formula to show psi, but the jist of this is that at idle/cruise the pump is generating about 6.5psi at the carb. When I get on it, that drops to barely 2psi and I'm not doubting that given a warmer day this would probably go lower.
At this point I'm researching a better fuel system setup. The factory hard line obviously will not be used, and I'm thinking of biting the bullet and just doing a full return style system with an electric pump, -8AN lines to and from the regulator and probably -6AN from regulator to the carb. This should hopefully resolve the fuel boiling issue at the carb I had last summer at the same time.