Modified Mustangs & Fords
460 Big-Block Build Part 2 - Large and In Charge
Hot heads and a hot cam make for a high-horsepower recipe
To prepare for the MPG heads, the short-block was sent to L&R Automotive for some minor machine work. Having been previously bored 0.060 over, the 460 block was treated to a quick hone to provide a fresh sealing surface for the new aluminum slugs. We elected to replace the factory dished pistons with a set of forged flat-tops from Probe Racing. The forged slugs not only improved the strength of the rotating assembly, but also increased the static compression ratio up to around 11.0:1. When it comes to performance, more compression equals more power.
The forged pistons were combined with the stock rods and crank, though the rods received new ARP rod bolts. Naturally, new rings and bearings were employed, as was a fresh set of Fel Pro head gaskets. Originally, we wanted to run ARP head bolts or studs, but time constraints forced us to reuse the stock head bolts.
To further power production, the revised long-block was teamed with a new solid flat-tappet cam from Cam Research. The healthy cam featured 0.638-inch lift, a 264/268-degree duration split (at 0.050) and a 110-degree lobe separation angle. Basically, we told the guys at MPG and Cam Research that we were looking to reach 600 hp and they gave us their 600hp (flat-tappet) cam and head package.
With our cam and heads ready to go, we turned our attention to the induction system. The stock intake was obviously not going to get us there, nor was the Weiand dual-plane intake used in Part 1. Knowing we were looking for power production higher in the rev range, we chose to top the 460 with a suitable single-plane intake pirated from a 514 crate motor from Ford Racing (PN M9424-H429).
The Victor-style intake was designed for high-rpm applications and features a 4500 (Dominator) carburetor flange. We think the motor would perform nearly as well with an intake equipped with a 4150 carburetor, but the Holley Ultra Dominator used for testing sure looked cool. If anything, it looked a little out of place next to the junkyard valve covers and unpainted cylinder heads.
A quick coat of paint would do wonders, but we were anxious to get the motor on the dyno. Additional components employed on the big-block included a set of 2.125-inch Hooker Super Comp headers (early Mustang chassis), a set of 1.73:1 aluminum roller rockers, and a factory electronic distributor. The final touches included a mechanical water pump, Lucas oil (both break-in and synthetic), and a quality K&N oil filter.
Unlike the previous buildup, we didn’t run each component individually, as the heads, cam, and intake were designed from the get go to work as a team. For this dyno test, we simply assembled the motor and plopped it on the dyno. Given the new rings, bearings, and (especially) the new flat-tappet cam, we subjected the motor to a delicate break-in procedure that included keeping the revs above 2,200 rpm for nearly 30 minutes.
Prior to assembly, the cam was liberally coated with moly-based assembly lube. To this precaution, we tossed in a bottle of high-zinc break-in lubricant from Lucas Oil and followed that up with high-zinc break-in oil. The final touch was that the cam was treated to a break-in procedure by Cam Research on its proprietary break-in fixture prior to shipping (a good idea these days with flat-tappet cams combined with elevated valve spring pressures). While this might seem a tad overkill, the flat-tappet cam survived the ordeal and performed flawlessly.
Once broken in, we dialed in the jetting and timing to the tune of 609 hp at 6,300 rpm and 557 lb-ft at 5,000 rpm. Though tuned for the top of the rev range, this combination offered more than 500 lb-ft from 3,800 rpm to 6,400 rpm. It was high fives all around after seeing the 460 thump out more than 600 hp with the stock iron headsI guess those MPG and Cam Research Corp boys know a thing or two about Ford performance after all!