Since poly locks thread onto the studs without any resistance, no wear is imposed on the studs, so in theory, they can be used indefinitely. This is why they are considered a "non-scarring device." The locking function is performed by the internal set-screw, which tightens down on the top of the stud, clamping the threads of the nut in place. Since you've pointed out that most aftermarket roller-rockers include a locknut, I suspect that you may be confusing terms, since just about all of the roller rockers we've ever used have a poly lock-style nut. As for the "protection," most racers have more faith in poly locks for holding their adjustments, while most garage mechanics would probably tell you the opposite. However, when in good condition and used properly, neither should loosen.
Pressure DifferentialI installed a GM Performance ZZ4 (Chevy small-block) short-block in my '78 Trans Am. It has cast-iron cylinder heads and a TCI automatic transmission with a 3,500-stall converter and 4.10 gears. The car is driven only about 1,000 miles a year. This past weekend, I took the car out and on the trip home I decided to open it up. With the converter I'm using, when I step on the gas the rpm really jump up fast. When I looked down at the oil pressure, it was reading 20 psi. When I let off, it returned to 60 psi. I stepped on it again and the oil pressure dropped back to 20 psi. I can't do anything to this engine with it in the car, but I would like to have a good idea what's wrong before I tear into it. Can you help? I am using a "live" oil pressure gauge in this car-not the factory electric one.Joe MinardBiggsville, IL
We tossed your question around a bit, pondering what could cause such a broad, yet consistent, swing in oil pressure. Some suggestions involved issues of windage-oil being whipped up in the oil pan by the crank, which in extreme instances can nearly empty the pan temporarily. We've witnessed this on the dyno with small-block Chevys, but only when the pan was overfilled. The extra oil was keeping the crank partially submerged, so when rpm got high, the whipping of the crank throws was splashing most of the oil up onto the cylinder walls. When this would happen, the oil-pressure gauge would falter, followed by a drop-off in power output, which was attributed to the hydraulic lifters collapsing as oil pressure went away. But your situation doesn't sound like that. Nor does it sound like a matter of oil slosh inside the oil pan. You'd have to be way low on oil to experience that kind of drop in pressure from slosh.
Kevin McClelland of Flowmaster suggested that you might have lost the pickup from your oil pump. Kevin has spent untold hours dyno-testing Chevy engines and has raced them for years. He suspects the oil level in the pan is sufficient to maintain a feed to the pump when the car is stationary, and maybe even as you drive normally. However, hard acceleration may be uncovering the feed hole in the pump cover if the pickup has, in fact, fallen out. Since that's a crate engine, the pump is probably a production piece, so the pickup tube may not have been welded to the housing, as is commonly done during performance rebuilds. Kevin also suggests that you might be able to peer through the oil drain-plug hole using a pen light or a flexible fiber-optic flashlight to see if the pickup is lying in the bottom of the pan before pulling the engine out.