The solid lifters were given...
The solid lifters were given a coating of oil, a smear of cam grease on their base, and dropped into place.
With the engine warm, we spun it around to get a cranking compression reading. With the hydraulic camshaft, the 440 spun over with 180 psi-gauge pressure. Comparing the hydraulic cam's cranking compression and idle vacuum against the solid cam going in later will give a good indication of how closely we sized the two cams. All that was left to do were the power pulls to see how the hydraulic cam performed. The 440 ran strong, posting 520 hp at 5,400 rpm peak output, and 557 lb-ft of torque at 3,800 rpm. Looking at the curve, we could tell that output above 5,700 rpm was dropping off quickly-a characteristic of the onset of valvetrain control problems-even though there was no audible float. We had a hunch the solid would fare better as the rpm ramped up.
In short order, we opened the 440 for surgery, stripped it of the hydraulic stick, and stabbed in its place our custom-ground solid. We had the engine up and running again within an hour and fired it up for a cam break-in cycle for 15 minutes at 2,300 rpm. Settling the 440 back down to idle, we found the idle quality was as good as we had with the hydraulic. The dyno instruments read 12.6 inches of vacuum at the same 900-rpm engine speed used before, showing a virtually identical match. The engine was shut down to reset the valve lash hot, and we spun the engine for a cranking compression test. This time we had 178 psi, again a reading close to the hydraulic stick's values.
The solid cam had our 440...
The solid cam had our 440 boasting over 550 hp, and turned it into a high-rpm powerhouse at engine speeds where the hydraulic gave up. Dyno man Brule likes solids.
OK, the two cams idled about the same and made about the same vacuum level, but what about power through the rpm range? Our question was soon answered, as we read the results from the dyno monitor. The solid cranked 550 hp at 5,800 rpm, and 559 lb-ft of torque at 3,900. Interestingly, the torque levels were quite close at peak, and below at the low-to-middle of the rpm curve. At higher rpm-about 5,200 and above-the solid cam walked away from the hydraulic, pulling cleanly to 6,300 rpm, at which we limited our test. The solid cam's power curve was nicely shaped, exactly what we like to see.
We had a 30hp gain, with the same "size" camshaft, with the peak horsepower coming in a good 400 rpm higher. There was no part of the curve where the hydraulic showed a clear advantage. Seeing is believing-when it comes to spinning it up, a solid flat-tappet cam does have the edge.