The 950-cfm Ultra HP is a conventional five-circuit carb with idle, transition, main, power, and acceleration circuits. these circuits all have removable jets for tuning. The 1050-cfm Ultra HP version of the Dominator has an additional intermediate circuit for a total of six circuits. The intermediate circuit in the 1050 picks up fuel from the float bowls through a set of jets in the metering plate, and then discharges that fuel into the air stream above the throttle plates through small tubes. This intermediate circuit is designed to smooth out the air/fuel ratio during the transition from idle to the main circuit's operation. It can be an important tuning circuit for cars that leave off of a transbrake or other situations where part-throttle performance is important. The Ultra HP design allows this intermediate circuit to be tuned by either changing the jets in the metering block or by changing the air bleeds in the main body.
With all of the tunable circuits in the Ultra HP carbs, there are a lot of ways to fix a mixture problem. There are also a lot of ways for a person to get confused, so before going nuts with the changes it is a good idea to jot down the baseline combination. We got lost a few times during our testing, but were always able to quickly return to the original calibration since we had kept good notes.
This 950 metering block shows the vertical row of replaceable jets in the emulsion well. the two jets in the power valve area are for adjusting the WOT mixture. The jets in the upper corners of the metering blocks are for the idle circuits. | 
A line-up of the various jets shows how they differ in size. On the far left are the main jets. The smaller jets in the center fit the air bleeds, while the super-small jets on the right are used in the metering block for idle and power valve restrictions. | 
We used the CamQuest 6 software from Comp Cams to select the best cam profile for our engine. Then we called up Comp Cams and had them send us the cam and springs, as well as other supporting parts. We've been re-using a set of Schubeck lifters for the last several motors, and they continue to work out great for us. |
Cam Selection
Picking a camshaft is often a bit spooky for the average hot rodder. Not only are there a lot of cams to pick from, but also a lot of terms to learn, plus it is a bunch of work to change the camshaft if you pick the wrong one to start with. Over the last several years there have been some computer programs developed that provided dyno simulations of different camshaft profiles, but none of them provided cam-selection help. With the introduction of the CamQuest 6 software, Comp Cams has combined a cam-selection program with a dyno-simulation program to give the novice engine builder an easier way to properly select a camshaft.
The CamQuest 6 software package loaded onto our computer with just a few simple commands, and we were able to quickly fill in the information requested by the program. We input the cylinder flow information for our heads, which is an important piece of data for the program. The program also requested information regarding the bore, stroke, size of carb, intended use of the motor, and so on. Once you fill in all that information, you are then able to select the type of camshaft you want to use, such as solid flat tappet, solid roller, hydraulic roller, and so on.
We needed to run 1.50-ratio rocker arms with the big MM 305 camshaft since our Comp (PN 26094) valvesprings were only good to .650-inch lift. We've used these Racer Brown rocker arms several times now with good results. We have upgraded the shafts with high-quality ARP studs, and we replaced the nylon spacers with some custom-machined aluminum spacers. | 
For this dyno test, we bolted on a super-stock-style aluminum oil pan with a dual-line swinging pickup. This particular oil pan is made by Charlie's and is available from Indy. We used a Socketless hose from Aeroquip for all of our plumbing requirements. We just recently started to use the break-in oil from Joe Gibbs for dyno testing. | 
We started the dyno testing with the smaller 950 Ultra HP carb. For these tests, we used a 2-inch spacer between the carb and the Indy 440-2 intake manifold. The headers are custom 2x32-inch dyno units from Stahl with 15-inch-long collectors. These headers are just about ideal for a motor of this size and power output. |
Once we entered all the necessary information and pressed enter, the CamQuest program came back with a recommendation to use the Comp MM 305S-10 camshaft. The MM 305 camshaft is one of the largest flat-tappet cams in the catalog with .305/.320-degrees of seat duration, .279/.287 degrees of duration at .050-inch lift, and .650/.630-inch of lift on the intake and exhaust. The CamQuest software also recommends the proper valvesprings and rocker arms to use with the camshaft, so a novice engine builder can order the correct parts the first time.
The CamQuest 6 package predicted 741 hp at 6,500 rpm, and 667 lb-ft of torque at 5,000 rpm when using the MM 305 cam with the Dominator carb and 708 hp with the smaller 950 Ultra HP carb. Those sounded like great numbers to us, so we ordered the MM 305 cam from Comp and got ready to make some serious power.