How to Build a 750hp Ford “Clevor,” the Engine Masters way.

Scott Main and team MPG Heads brought a 404-inch, Cleveland-headed, small-block Ford to do battle against the rest of the small-block class at the 2016 AMSOIL Engine Masters Challenge presented by HOT ROD. Scott likes the small-block Ford platform because of its great cylinder head design and knew he could whip up a stout competitor with some hardcore time on the dyno and by selecting the proper parts. Scott told us that Cylinder Head Innovations (CHI) is always happy to work with engine builders in developing performance packages, and they, “seemed to be the top of the food chain for that RPM range.” In other words, right where a 400-inch street engine needs to be making power. So how does CHI, an Australian company, wind up making one of the top Ford cylinder heads? While Windsor took over in the States, Australian production of the Cleveland continued on until the early 1980s, and remaining stocks of the engine were used in new trucks until 1985. As Scott said, “In Australia they're all about Fords and Clevelands are huge down there.”

MPG heads tried several varieties of CHI heads and found the one the worked best for the competition parameters, developing a port shape and five-axis CNC-porting both the heads and intake. The resulting ports offer both high flow and high efficiency, delivering flow at modest lift levels. Scott grinds his own cams using 8620 billet steel blanks, so he had plenty of opportunity to try different duration and lift, but found that increasing lift from his chosen .750-inch lift didn't add significant power at the cost of valve spring longevity.

The heads are so efficient didn't need much lift to get the job done.” – Scott Main on the CNC-ported CHI heads

Come competition day, the hot-rodded Ford averaged 578.8 lb-ft and 606.3 horsepower between 3,500 and 7,500rpm, with a peak power of 756hp, earning the team the small-block class win. Scott was pleased with the peak number, as his testing was done in his Colorado shop. The 6,000-foot elevation isn't conducive to big numbers, “I was surprised that at the lower altitude the engine kept making power.” Even more impressive is that there are no secrets about the engine, no exotic parts, and no trick epoxied intake runners. Here's how Scott Main and Jay Kidwell built a streetable, repeatable recipe.

Mile High Crankshaft prepared the 4.017-inch crank that was fitted with 5.995-inch SCAT connecting rods and Diamond pistons.

The CNC-ported 3V heads, from Australian company Cylinder Head Innovations, flow 400CFM at .750-inch lift and a Cam Research cam provides 250/260 degrees of duration at .050. The cam choice was the result of lots of experimenting on the dyno with different bumpsticks. Scott told us, “The bad news is that it's a lot of work, the good news is that you learn a lot.”

Each part of the combination helped win the class, and that definitely includes the headers. Scott tried a lot of different header collector styles, but found that the wide RPM range of the Engine Masters competition meant that while the peak power would move up and down in the RPM range, the overall average was very close. The team found that 2-inch primary Hooker headers stepped down to 1-7/8 right at the 3-inch collector cone worked best. As Scott admits, “it goes against conventional wisdom”.

On top of the CHI heads is a CHI 3V intake ported to match. Jay Kidwell at the Carburetor Shop in Denver built the 1350CFM carburetor based on a Holley Dominator main body. It's the very same carb that he drives on the street in his 9-second Nova. The low-rpm performance sold the team on the carb. Scott said, “We haven't found anything that can beat it. At 6,000 feet it can still load down at 2,200rpm on the dyno and it flowed fuel no problem.” The carb is going back on the Nova when it gets home, while the engine is going back into the dyno cell to put more camshafts to the test.

The MPG Heads team ran five quarts of Amsoil oil. Testing with a smaller pan didn't make much difference, but a windage tray that came with the pan did. Oil pressure was fluctuating during a dyno run, so the team pulled the pan, put the tray in, and immediately made a run. The oil pressure was fine and they picked up 15hp gain just from the tray.

The Clevor water crossover from CHI allows for Cleveland heads to be mounted to plentiful Windsor blocks.

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