With the pistons installed,...
With the pistons installed, the number 1 piston is brought up to TDC in order to begin the cam degreeing procedure per the cam card.
For the second pull, we increased the jetting to 87 on the driver side and 85 on the passenger side on both outboard carbs. Timing was bumped from 36 degrees to 39 degrees total advance. The second pull responded with 376 hp at 5,200 rpm, and 417 lb-ft of torque at 4,200. The A/F ratio was still a tad lean, dancing in the 13.6 range.
On the third pull, we upped the jetting to 88 on the driver side and 86 on the passenger side. This pull responded with an A/F ratio of 12.7:1 at peak horsepower, but the horsepower numbers didn't show a substantial increase.
The final tally was 377 hp at 5,200 rpm, and 417 lb-ft of torque at 4,200. It was almost a mirror image of the previous pass. We figured there weren't any gains from jetting, so we played with the timing some more. We began by moving it back down to 36 degrees total and lost 4 hp and 5 lb-ft of torque from our peak numbers. Once we moved the timing back up to 39 degrees, we were ready to hit the track for some testing.
Getting a car in the F.A.S.T. class of racing to launch requires a lot of finesse with the throttle pedal. If you're wondering why, just take your stock, Mopar-powered anything out on the street and try to take off really quickly without spinning the little repop redline tires on your ride. With the finesse required-and the fact that Doug leaves his car in Drive when he races-the Road Runner has still posted a best quarter-mile time of 12.16 at 115 mph. Give him a little more time behind the wheel and 11s are definitely within reach. Keep in mind that this engine uses a stock intake manifold with three Holley carbs, as well as stock exhaust manifolds.
One of the 906 heads is installed,...
One of the 906 heads is installed, and valve-to-piston clearance is checked. A minimum of .080 inch for the intake valve and .100 inch for the exhaust valve is recommended. The heads were prepped at Modern Cylinder Head in Clinton Township, Michigan. The intake valves are 2.14 inches, and the exhaust is 1.81 inches. The ports feature a full porting and polish job.
Once the engine is assembled,...
Once the engine is assembled, it's tested to assure there's no excessive leak-down around the valves and rings.
The oiling system is prim...
The oiling system is primed.
After receiving accessories...
After receiving accessories such as the intake and carbs, oil pan, and exhaust manifolds, the engine is installed in the car-a '69 1/2 lift-off-hood Road Runner that will race in the F.A.S.T. class. This class dictates that the car look factory stock. Of course, looks can be deceiving.
Dyno Dueling Once the engine...
Dyno Dueling
Once the engine was installed, the Road Runner was taken to AP Engineering for dyno'ing. AP utilizes a Mustang chassis dyno, and its results are quite consistent. Not a large amount of tuning was required on the dyno. Carburetion was tuned with the help of Promax Carbs metering blocks and the addition of 50cc accelerator pumps. The Promax metering blocks allow the outboard carb jetting to be changed as needed. Factory-prepped outboard carbs were not supplied with changeable jets. The only other changes made were to the timing until the optimum setting was found.
The carbs may look stock,...
The carbs may look stock, but thanks to the aid of the Promax jetable metering plates, fuel and air flowing through the outboard carbs can be adjusted for maximum horsepower.