Building an AMC Brute

We asked a couple of builders about off-the-shelf pistons and got headscratching and thinking but no part numbers. This engine uses a customLunati aluminum-alloy forged flat-top for future use of race gas andnitrous. At around $640, it is the most glaring expense on this engine.The slugs have a 1.48-inch compression height with two 17-degree valveeyebrows spaced 1.590 inches apart with a total of 11.23 cc's of relief.With a 0.043-inch thick gasket, 0.020-inch deck clearance, and the 64ccheads they're good for 10.0:1 compression.

Cylinder Heads

There are Indy and Edelbrock heads available for the AMC, but Tichnerwanted to use the stock dog-leg heads. The cork in their design is theintake runner and the exhaust-port-to-header match. Payton's put inabout 11 hours of work to cut the stock valve seats and fit a set of2.08 intake and 1.625 exhaust valves and raise the intake runner.Payton's machinists are careful to avoid the intake floor, because pastexperiments found that changes there actually hurt airflow. Extensivework in the combustion chamber was performed to unshroud the valves andopen the chamber from 58 to 64 cc's. This was also helpful in reducingthe compression on this engine to run on pump gas. The final flownumbers were 279/210 cfm at 0.700-inch lift at 28 inches of water. Thoseare big ports for a cast-iron street head.

On the exhaust side, the rough casting was cleaned up and the headerswere port matched to the heads. Early Super Comp 17/8-inch full-lengthheaders for the '68-'74 Javelin/AMX and '74 Matador need to have theflange opened up a bit to match the exhaust port, but new headers ofthis design should already be modified to fit.

Carb And Ignition

This engine was built with the future installation of Holley's Commander950 MPFI kit in mind. It has a single-plane manifold and throttle-bodyincluded. For the dyno run, Tichner used a manifold that is similar indesign from Herman Lewis Racing and a 950-cfm Holley HP Seriesmechanical-secondary carb. The cfm might seem a little much, but thisengine is going into a light AMX that will likely see more WOT on thetrack with a plate of nitrous than street cruising. According toPayton's dyno sheet, the A/F ratios were correct for this size carb onthis combination.

MSD offers both a standalone ready-to-run distributor and the Pro-Billetthat requires an MSD 6-, 7-, 8- or 10-series ignition to operate. Bothcome with a vacuum advance and replace the stock points stuff. Tichnerchose the Pro-Billet and a set of Autolite AR52 racing plugs to spark itall.

Cam and Valvetrain

The cam was a sacrifice to get some vacuum at a loaded idle. It is aLunati hydraulic flat-tappet grind with 230/235 degrees of duration at0.050, a valve lift of 0.0523/0.0540, and 108 degrees of lobeseparation. The full-kill cam is also a Lunati grind, but it uses asolid lifter and has 249/259 degrees at 0.050 and 0.579/0.598 lift withthe same lobe separation angle. It will sacrifice more idle quality andvacuum but would likely crest 500 hp on this combination. The rockerarms are aluminum rollers made for a Ford 260-351W but useable on the090 and 993 castings with Lunati springs with 105 pounds of seatpressure at 1.80-inch installed height.

The AMX

Ultimately, the engine is destined for Tichner's AMX. We'll let him tellits story.

By Bill Tichner

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