Why the Mark V?
The Mark V engine was an intermediate step in the evolution of the big-block Chevy, fixing problems encountered with the Mark IV engine, most notably leaky mains and oil pan gaskets. The Mark V engine does not use a bolt-on oil filter bypass and required the installation of check valves into the engine to make it work with such systems. (If you forget, the engine will appear to make proper oil pressure, but it will be missing the engine and only circulating through the oil filter system-for the time your engine will continue to run.
CamQuest 6 Asks, "Can We Do Better?"
Our 540-cid Chevy big-block Mark V engine was a standout performer. It did everything we asked it to do. But did we optimize the performance? Did we get everything we could from the combination? Knowing that we were up for anything the learning curve might throw our way, we decided to test our camshaft knowledge against the newest programming available from COMP Cams-the CamQuest 6 Cam Selection Software.
As touted in the ad materials, the CamQuest 6 is a PC-based camshaft selection program that allows the user to find the right camshaft by answering a few application-specific questions from the program's dropdown menus. Sounds simple enough, so we took the program for a testdrive.
First, we input the parameters required by the program, such as engine type, compression, carburetion, cylinder head type, etc. The program offers up an amazing number of possibilities. For our Mark V big-block engine, the program was easy to understand and required little intuitive thinking on our part to fill in the grids accordingly. Our only "gray" area occurred with regard to the flow figures of our ported RHS Pro Action 360cc cylinder heads. Having the exact measurements here would give us more accurate information in terms of the total calculation, but we were comfortable in running the simulation with the data we had in hand. The CamQuest 6 calculated the data and kicked out a number of good, better, and best camshaft choices. Interestingly enough, our model RA306-10 (0680-inch lift and 306/319-degrees duration, 110-degree lobe centers), the one that generated 649hp on the Westech dyno, was not the top CamQuest 6 camshaft selection. So what did the CamQuest 6 recommend? Camshaft grind number RA296ER-8 with less duration and more lift on 108-degree lobe centers.
To determine how much better the smaller-duration camshaft would be, we did two virtual installs using CamQuest 6. As it was the top pick, the program used grind RA296ER-8 and displayed the results, along with all of the recommended ancillary COMP Cams parts like lifters, retainers, springs, locks, and other parts that should be used to achieve optimum performance. Grind RA296ER-8 (the top CamQuest 6 camshaft selection) features 108-degree lobe centers, with only 296-degree intake duration (304-degree exhaust). Lift was increased to 0.714 inches. Our new estimated horsepower-nearly 689hp. Torque-655. So why the 30hp difference? We decided to investigate.
The RHS Pro Action heads use...
The RHS Pro Action heads use high-quality guides. These were lightly honed to create an excellent valve to guide fitment.
A light coating of white grease...
A light coating of white grease was applied to the COMP Cams rocker studs' threads before they were torqued in place. The white grease ensures they will come out if necessary without damaging the aluminum cylinder head. COMP Cams also makes the pushrod guideplates shown here.
This camshaft installation...
This camshaft installation tool from Gear Head Tools is handy for sliding in the camshaft without damaging the fragile camshaft bearings. Note that the camshaft was liberally lubricated with COMP Cams break-in lube prior to installation.