The HVX (Hoover VW Experimental) mod is an oiling system modification. If you look at the original lifters you'll see that they have two oiling grooves, and that oil only gets into them and down the push rod when the lifter is pushed (otherwise the oil simply follows the other groove to the next lifter.) It also gets more oil to the right side lifters. Then in the rocker arm area the rocker arms and shafts are grooved in order to get more oil through them. Some of that oil then goes down the drilling in the tip of the rocker arms and feeds a swivel style valve adjuster, which according to Bob Hoover creates a spray bar effect. Then the extra heat added to the oil is removed by a larger oil cooler.
HVX Mods
Ah! I also have a 34 PICT-4 carburetor with a variable accelerator pump. The problem is that the thermovalve on the accelerator pump is not opening at the correct temperature.
I got this particular carburetor just because it has that valve and it would be nice for getting better fuel mileage. But now I have to figure out where to either get another one or how to fix this one.
