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FordMuscle.com Install & Test RHS SBF Cylinder Heads

Article courtesy of FordMuscle.com.

About a year-and-a-half ago we introduced you to a basically stock 1966 Mustang. At that time its’ owner Heather was ready to get into some basic power upgrades in the form of a carb and intake swap. However, being novices to the hobby, she was unsure which of the many brands and combinations were right for her car. We thought this resembled the dilemma likely faced by thousands upon thousands of new comers to the hobby. So we teamed up with Heather and her husband to chronicle their progress. At their pace we help them with the next logical modification – both in terms of power but also in terms of their growing mechanical abilities, because they perform all of their own installations. We document all the hurdles and challenges they encounter because we believe it is useful information for many new enthusiasts. After all, in the real world (as opposed to the glossy magazine world) this is how the hobby is playing out in garages everywhere. Not every enthusiast is an expert in the hobby, with deep pockets and a penchant for maximum horsepower.


When we last left Heather’s Mustang they had tested a couple of popular 4-bbl intake and carburetor combinations (see My First Intake and Carb Upgrade.) Heather left the dyno quite content with a Weiand Action Plus manifold and Edelbrock Performer 600cfm carburetor. This combo made the best horsepower (171 horsepower and 226 ft.lbs. of torque), and offered trouble free daily-driver operation.

So this set our baseline. She’d been driving the car, trouble-free, for the last 16 months until this summer when the wrenchin’ bug bit again. So we suggested it was time to swap out the 289’s iron heads and stock cam. They were game.

Next Step: Heads and Cam
For this project we selected RHS™ Pro Action™ Small Block Ford 160cc cylinder heads. These aluminum heads feature 1.94″ intake and 1.60″ exhaust valves. The 1.94″ intake is a new offering from RHS, as some of you may recall they previously only offered a 2.02″ valve making it mandatory to clearance stock pistons. The 1.94″ valve will bolt right on with stock pistons so long as the cam duration and lift are not too wild. This is good news for amateur hobbyists, heck even experienced ones, who aren’t prepared nor comfortable cutting their pistons while in the motor is in the engine bay.

For the camshaft we selected Comp Cams‘ Xtreme Energy XE256H (part number 32-234-3). This hydraulic flat-tappet cam is mild by most standards, but a decent step up from stock while retaining great idle and yet improving torque. At 212/218 degrees duration and .477/.484 lift we know piston-to-valve interference will not be an issue, and this cam will take advantage of the better flow of the new cylinder heads. The RHS 160’s flow in the neighborhood of 260cfm at .500″ valve lift (intake) and 180 cfm on the exhaust side.

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