Heads And Cam Package
We decided to try the Racing Head Service (RHS) 180cc aluminum small-block Ford heads on our little 302 because we had heard good things from our Ford buddies about them. Right away we were impressed when we bolted one up on the SuperFlow 600 flow bench and watched as the as-cast intake port generated 249 cfm at 0.500 lift and 255 at 0.600 inch of valve lift. With solid midlift intake flow numbers and good exhaust-to-intake flow data, the heads looked promising. Combined with a Comp Cams hydraulic roller with 0.550-plus lift, they promised good power. Even better, the compression jumped from a stock 8.85:1 to 9.5:1 with the RHS 58cc combustion chambers.
Before we bolted on the new RHS 180cc heads, we added a set of Comp 939 dual valvesprings
The RHS guideplates did not accurately line up the rockers with the valve-stem tips on the
This required Brul to use a chop saw to cut a slot in between the rocker stud holes and al
We had to swap in stronger valvesprings because the heads we ordered did not come with sufficient spring pressure to handle both the rigors of higher engine speeds and the demands the blower would place on the back side of the intake valve. Using Brul's recommendation of 200 pounds of load on the seat at the installed height of 1.800 inches and 400 pounds across the nose at max lift, we opted for a set of Comp springs that both fit the head perfectly and also produced the load necessary to keep the valvetrain together at the engine speeds we knew were imminent.
|CAM SPECS |
|Camshaft ||Duration ||Duration ||Lift ||Lobe |
| ||(Adv.) ||(@ 0.050) ||(in.) ||Separation |
|Stock Ford cam, int. ||266 || - - - ||0.445 ||115 |
|Hydraulic roller, exh. ||266 || - - - ||0.445 |
|XE274HR-12, int. ||274 ||224 ||0.555 ||112 |
|XE274HR-12, exh. ||282 ||232 ||0.565 |
We also had to drill and tap the accessory bolt holes in the front of the head to bolt on
|HEAD SPECS |
|RHS Pro Action 180cc small-block Ford aluminum head |
|Part number: ||35004-02 |
|Intake port volume: ||180 cc |
|Exhaust port volume: || 66 cc |
|Valve sizes: ||2.02/1.60 |
|Valve angles: ||20 degrees (stock) |
|Chamber volume: ||58 cc |
|The head comes assembled with screw-in studs and ||guideplates. |
Dyno Numbers Don't Lie
Test 1: Stock 302 long-block with Edelbrock Performer RPM intake, Race Demon 625 cfm carburetor, and 1 31/44-inch open headers.
Test 2: Stock 302 long-block with same configuration as Test 1 except with added Carb Shop 750 cfm Sportsman carburetor and ATI ProCharger P-1SC supercharger.
Test 3: Added RHS 180cc aluminum heads, Comp XE274HR cam, reused Edelbrock Performer RPM intake, Race Demon 625cfm carb, and 131/44-inch headers.
Test 4: Same combination as Test 3 except with added Carb Shop 750 blower carb and ATI ProCharger P-1SC supercharger.