Jon continued, "I talked to COMP Cams and they helped me out with ideas on the duration. I had two different sets of cams, and in the end had one set reground, so I had quite a few variations to try out. I tried a lot of different things, and it is basically trial and error. I started out with the biggest cams, and I had those cams in every possible position, with wide lobe separation, narrow separation, way advanced, way retarded, just everywhere, because they are easy to move. It was pretty consistent that the intake wanted to be at around 98 degrees centerline, and when I finalized everything, the exhaust was the same, it wanted to be at 98 degrees. You can say I was at 98-degree lobe-separation angle, and zero advance. One observation I made from the EFI cam sensor, which reads in degrees, is that from 3,000 to 7,000 rpm the cams will retard about 5 or 6 degrees. You couldn't ask for anything better than that, it is just what you want."
The key advantage of the four-valve is that virtually the entire chamber is used for valve
While the four cams seem exponentially more complex, Jon tells us, "It wasn't that hard. For this contest the intake lobe is going to want to be between 92 and 100 degrees. That will work the best, especially with a compression-ratio limitation. With 11.4:1 compression, the engine still produced about 240 to 250 psi cranking compression, which helps down low. At the same time, the later you open the exhaust the better off you are going to be down low, so having the exhaust in at 98 degrees it opens late and that helps you. It wasn't that hard to figure out; I knew about where it wanted to be and that's about where it ended up. On these kinds of engines especially with their good exhaust flow it wasn't going to need a lot of exhaust cam. Initially I had less exhaust than intake, but I ended up with them both the same."
Nothing really outlandish was needed in the valvetrain; the factory Ford components proved to be excellent. As Jon explained, "The rockers have a roller wheel and 1.8:1 ratio, and it really works out well. I never had any trouble with the hydraulic adjusters. I tried shimming them and making them almost solid, and it really didn't matter, they worked fine no matter how you did it. In the end I just ended up removing the limiters and running them as original. I never had a bit of trouble as you might have with a hydraulic. With these engines the spring loads are much more modest than we are used to with the larger valves of a pushrod engine. I used COMP Beehive springs with loads of 115 pounds on the seat and 280 pounds open. If you look at the valves they really weigh very little and they have titanium retainers on top of that, so the relatively light spring loads offered all the control required in this operating rpm range."
The DOHC mod uses a long chain from the crank to drive the exhaust cam, with a short chain
The induction system consisted of a factory '00 Mustang Cobra R intake manifold with an Accufab throttle body. This rather rare intake manifold is a two-piece unit, with laid-over individual runners enclosed in a separate plenum housing. Kaase found this intake to offer the broadest powerband, "When I first got it running, I had a four-barrel intake manifold, and the engine made as much as 2 hp per cubic inch. The thing is, for the EMC competition you need to have very good low-end torque to score well, so it goes to show you that even with everything else going for you, with one wrong component, it still will not give the power curve you want. We had to give up a lot of that upper-end power to make it better down low."
Jon continued: "The manifold is a two-piece design and is hard to find, especially the top. On the bottom I ported it a little bigger, but I don't know if that really mattered because I started out with it un-ported and when I ported it, it didn't really help it. It is pretty small, but it still makes pretty good power. The biggest thing I did to it was shorten the runners a little bit, because they were really close to the sides of the top cover. There were a few places where the entry to the runners was a half inch from the top cover. I cut about an inch or more off the runners and angled them back. I made radius entry rings out of aluminum plate to give the runners a good entry. The shorter runners really helped from about 4,000 rpm and up, mostly because the stock runners were just too close to the top cover wall."
The induction development continued with the fuel injection, as Jon details: "The other thing I did is experiment with the injector position. When the injectors were in the original position, there was only about 5 lb-ft of difference, but 5 lb-ft is the difference between a win and loss at the AMSOIL Engine Masters Challenge. With the injectors in the stock position, it was easier to get the tune correct, and you could see it was clean in the plenum. When I moved the injectors up the runners like I ran them, you could tell it had more standoff, and you could see the fuel staining in the plenum. It was much harder to tune, and I had to really chase the fuel curve for each cylinder through the rpm range, with the greatest difficulty being below 4,000 rpm. We tried it with the injector at the mouth of the runner, but it didn't work out well. The pulses would throw the fuel out of the port and it would go everywhere."
The mod uses roller cams with a large base circle, and feature balance counterweights. The
Kaase retained the full production valvetrain, including the hydraulic lash adjusters and
With the plenum removed, we gain a peek inside the intake showing the radical cross-ram de