Since Moore fully intended...
Since Moore fully intended to spin the jeebers out of his 331, he searched out a '68 Mexican casting that offers thicker main webbing and caps for a little more strength. These blocks can be identified by the casting Hecho en Mexico (Made in Mexico) in the lifter valley.Cerveza es bueno!
Moore went with a Comp Cams mechanical roller, since there's really no reason for a hydraulic cam to be spinning more than 7,000 rpm. The advertised specs look especially big at 274/280 for a 331ci engine, but at 0.050-inch tappet lift, the numbers come in at 236/242 degrees. To be technically accurate, we also have to subtract 1/2 degree per 0.001 inch of lash that is required for clearance to compare these mechanical lifter numbers with what most enthusiasts recognize as hydraulic cam numbers. With 0.16 inch of intake lash, subtract 8 degrees from the 0.050 duration numbers, which reveals the true specs of 228 degrees of duration at 0.050-inch tappet lift. We combined good Comp mechanical roller lifters, 0.080-inch-wall-thickness Comp Hi-Tech pushrods, and a set of 1.6:1 Pro Magnum roller rockers, tied in with the ARP 7/16-inch rocker studs and AFR roller cam valvesprings-and never once experienced valve float difficulties. This immediately motivated us to consider swapping to a set of 1.7:1 roller rockers, but we ran out of time before we could take this engine to that next level.
| CAM SPECS |
| Camshaft | Duration
(Advertised) | Duration
(at 0.050) | Lift | LASH | Lobe
Separation |
| Comp roller (intake) | 274 | 236 | 0.602* | 0.016-inch | 110 |
| 35-770-8 (exhaust) | 280 | 242 | 0.608* | 0.018-inch | |
There is a small amount of...
There is a small amount of block-clearancing necessary to create room for the longer stroke and especially for the Scat H-beam rods. The bottom of the cylinder bores only needs a minor amount of trimming.
These are gross valve-lift numbers that do not take into account the lash. Subtracting the lash creates a net intake lift of 0.586 inch and an exhaust lift of 0.590 inch. These numbers are based on a 1.6:1 rocker ratio.
Test Day
Our first pull to check the air/fuel ratio indicated where we were headed when torque was still climbing at 5,000 rpm. We ran a Holley 750-cfm Street HP carburetor and an Edelbrock Super Victor single-plane intake manifold, and the fuel curve was incredibly steady allowing us to concentrate on optimizing the package. With peak torque at 5,600 rpm, the horsepower peaked at 7,400 rpm with 480 hp. Not only is this almost directly on top of our 1.5hp/ci goal, but it's also very repeatable with several runs at that level. Timing and jetting changes produced a few minor improvements, and then we bolted on a Wilson 1-inch open spacer that finally helped us kick the peak power up to 496 hp.
Moore also included a TFS-built...
Moore also included a TFS-built main-cap girdle that will clear the Milodon oil pan and pickup assembly. The girdle ties all the main caps together to reduce crank movement, especially at high engine speeds.
With an 1,800-rpm powerband between peak torque and peak horsepower running a solid 1.5 hp/ci and plenty of durability, there's little more we could ask of this stroked-block Ford other than maybe 4 more horsepower so we could claim 500. In post-testing discussion with AFR's Tony Mamo, he suggested the 185cc Outlaw Street heads would probably have made the same peak power while also pumping up the midrange torque slightly. Here's a case where being a little more conservative might have made even more power. How can you lose on a deal like that? We also have to admit that in the car, these numbers will drop a little after fitting the engine with chassis-style heads, an accessory drive, an air cleaner, and other accouterments that must accompany a street-driven engine. But the fact remains that this is one stout small-block Ford.
Dyno Tales
Test 1 is the initial test as configured in the initial buildup of the engine, including the AFR 205cc heads, Comp mechanical roller cam, Edelbrock single-plane Victor intake, 750-cfm Holley HP carburetor, and 13/4-inch headers with open exhaust.
Test 2 added a 1-inch open spacer to the intake manifold, with all other components remaining the same.