The 51 chev had a booster pump for when manifold vacuum was too low.
All I know is we didn't have that setup. The '51 had been upgraded slightly, in that we replaced the old 216 with a 235, ran a split exhaust manifold with dual exhaust, and upgraded to 12 volts. But the vacuum line from the wipers went to manifold pressure, not sure if it was a port on the manifold, or if it was on the carburetor, but we didn't have the booster on the fuel pump, or the wipers hooked to it.
Of course, we also didn't wire the fuel gauge to 12 volts either, or put a regulator in to drop the voltage to the gauge, so we had to rely on the odometer for fuel ups, so we could have bypassed the fuel pump booster, too. It was my dad's truck before it was mine, and I helped with it, but all the work was done 25+ years ago, and my memory has faded a bit. We had so many car projects over the years, they've kind of blended together at points, but I do remember the wipers slowing or completely stopping on acceleration.
Maybe a difference between cars/trucks? I don't know. It's been nearly 10 years since I had the truck, but I could dig out some old photos of the engine bay to do a look-see.
Well, our conversation encouraged me get in contact with my dad on the pump. Apparently, there were a few varieties of fuel pump available, and the one my dad chose had the glass bubble to see the fuel through (he liked the looks of that one over the all-metal, dual-action version), so he wound up running the vacuum from the manifold. He said the original pump on the 216 was the dual-action pump, he just preferred the glass bubble version when he re-did it.