This photo shows the laser...
This photo shows the laser installed in the side of the block. We painted the valves with a white paint so the laser would read the movement better. Each time we made a change, we had to realign the laser on the valve. SpinTron is currently working on a dual-pickup setup, which will be able to read an intake and exhaust valve at the same time. It will require holes on each side of the block to read from different cylinders.
Jerry Pelkey of SpinTron told us we would leave with more questions than answers-and boy was he right. We did learn where we would lose control with various parts. We also could see the benefit of lightweight parts such as hollow-stem valves and titanium retainers. Most of all, we saw how different thicknesses of pushrods, coupled with spring pressure, changed the characteristics of the valvetrain.
We had heard about lofting a valve from the cam lobe. In essence this is free lift and duration. By utilizing certain components, it's possible to have controlled loft so it can land the valve gently as it closes. Most of the punishment of a valvetrain that has lost control is on the closing side of the camshaft. As you can see by the graphs, that's where the valve is literally bouncing off the seat (see Lofting the Valve Graph).
OK, you're asking, "What did you learn?" If the Novi 2000 were still legal and they hadn't changed the rules, I would rule the class. I saw where we went wrong, and I'm going to experiment with lofting the valve off the cam. It's like changing cams. The downside is, it can bite you in the butt. Missing a shift and over-revving the engine could result in the valve hitting the piston. Been there, done that-it isn't cheap.
Lief had split a stock timing...
Lief had split a stock timing cover before we arrived. This allowed us to change cams without having to remove the timing cover. After dropping the chain into the oil pan, we got smart and used an Allen wrench to hold the chain up out of the pan. We had no leakage on the timing cover during the testing.
These are my recommendations for a hydraulic-roller cam engine. Set spring pressure between 150 to 200 on the seat. Those springs from Anderson Ford work well. The conical springs are also good, but they will cost a bit more. Titanium retainers are not just for race cars. They are stronger and lighter than steel. They cost a lot more, but you'll appreciate it in the long run. Use only the lifters from Ford Racing Performance Parts, and check them regularly. Use the thickest-wall, largest-diameter pushrod you can. A 31/48-inch, 0.135-wall pushrod from Trend Performance works well. You may need to clearance the pushrod holes, but it will be worth it. Find a cam manufacturer that uses the newer cam-grinding machines. The technology has changed, but a lot of companies have not. The advancements in lobe design focus on controlling the valvetrain. Cams such as the Anderson Ford Motorsport Hi-Rev Series use this CNC technology. Upgrade to the 71/416-inch studs if you use a stud-style rocker arm. The Trick Flow rockers we used worked well.
Try as I might, I could not...
Try as I might, I could not get AskRobin.com on the SpinTron computer. Can you believe Gerry and Leif turned me loose on this thing? The software allows the user to set up predetermined rpm to sample. Click the mouse to start the process. It makes a lot more noise than you might think. At different rpm, the valvetrain makes different noises, and we could hear when the valvetrain lost control. We were a bit conservative and didn't want to continue when major float or bounce was detected. Don, on the other hand, wanted to see parts flying off the test engine.
If you plan to run the car on the street, adjust the preload as you would normally. When you go to the track, run the lifters as close as you can to bottomed-out. We use a dial indicator to find the optimum setting. Be careful not to run the valves so tight they are open, which can result in contact with the piston and a bent valve or two.
It's amazing we're able to see the numbers in these engines. Certainly no one except the NMRA will use stock cams. They aren't designed for high rpm and our testing showed that. But with some good parts and a little testing, you can make a hydraulic-roller cam run high rpm. Racers in the NMRA Pure Street class, such as Rich Groh (now in Renegade) and Ron Anderson, run in the 9,000-plus range.
Horse Sense: The SpinTron is a machine that's powered by a 50hp electric motor and is used for testing valvetrain components. Once an engine block has been mounted to a fixture on a SpinTron, a mandrel is installed in place of the crankshaft, and a hole is cut into the side of the block where a laser is used to measure valve movement. With the electric motor spinning the engine to 12,000 rpm, information from the laser tracking is sent to the SpinTron software where it plots valve movement. Different rpm points can be set up to capture data and review it with the software at a later time. Every NASCAR and NHRA Pro Stock engine builder uses a SpinTron. Most are in the hands of cam manufacturers. Initially, Bob Fox built three machines-one for his company, Trend Performance, and two others to help offset costs. Hendrick Motorsports and Comp Cams bought those two units. To date, about 100 machines have been built.