It was now time to install the engine in the Dart, and fire it up. With the engine's oil system pressurized and the fuel system primed, the key was turned and the engine jumped to life. Once running, the timing was checked, and several adjustments were made to the new 1920 Holley carburetor. The engine was run at 2,000 rpm for 30 minutes, to break-in the new camshaft and tappets. The oil pressure remained constant during the entire break in period, and after the break in, the valve lash was checked. Once everything was checked, the Dart was taken for a little spin around the campus. The engine temperature remained steady and on the cooler side, and the Dart had nice acceleration. Back at the shop, the fluid levels were checked again, and the Dart was inspected for any problems or leaks. Everything looked good, and it was time to test the new engine on the dyno.
With the Dart strapped to the chassis dyno, the engine brought up to operating temperature. Everything looked good so we let it fly. With very conservative ignition timing (initial timing was set to 5 degrees BTDC, but the distributor advance slots had been modified to limit the advance, so the total timing was only 19 degrees BTDC), the engine was run at WOT from 1,500 rpm to 4,000 rpm. This gave us a torque reading of 123.683 lb/ft. of torque at 3,150 rpm, and 77.936 horsepower at 3,500 rpm. So now we have a baseline for the start of the aftermarket bolt-on components class.
| PRICE TAG
|Master Rebuild Kit*
|Ignition Control Box
|Ignition Wiring Harness
|ARP Rod Bolts
|Mopar Paint (Red) (4@$8.99)
|Holley 1920 (Reman)
|Intake Valves (6)
|Exhaust Valves (6)
|Valve Springs (12)
|Champion Spark Plugs (6@$1.79)
*Master Rebuild Kit Included: Pistons, Rings, Gaskets, Cam Bearings, Rod Bearings, Main Bearings, Oil Pump, Freeze Plugs, Camshaft, Solid Lifters, Pre-lube, and Timing Set. All machine work was handled at Penn College's machine shop. Block decking, head milling, rod resizing, new guides, valve seat prep
6. The cast pistons were part of a master overhaul kit from Napa. They were attached to the reconditioned connecting rods, and installed.
7. When it came time for a camshaft, a conservative stick was chosen. The Mopar cam has .406 /.4140inch lift, and an advertised duration of 244 /244 degrees.
8. With the addition of the reconditioned head, the long block is complete. The head was also milled .060 inch, and given a three-angle valve job. New valvesprings were installed, and the factory rockers and shafts were cleaned and re-used. With all the decking and milling work performed on the block and head (.120-inch removed) the rocker shafts were shimmed .035-inch to reestablish the correct rocker geometry. The compression ratio was raised to a pump gas friendly 9.37:1.
9. The rebuild is complete, with the addition of the Mopar Performance orange box electronic ignition, the engine oiling system was primed and all the fluids topped off. A new battery was placed on the battery tray and attached to the battery cables. The carburetor is a remanned Holley 1920 with the same part number as the original. The break-in of the engine was successful and a quick test drive was encouraging as the Dart drove very well and there were no strange noises or leaks.
10. In the car, and on Penn College's Mustang chassis dyno, the initial numbers for the Dart's 225 were 123.683 lb-ft of torque at 2,800 rpm, and 77.926 horsepower at 3,600 rpm. Now that the baseline has been established it is time to improve upon the combination with readily available aftermarket parts while maintaining a streetable pump gas compatible engine. We're thinking that a performance camshaft, and intake and carburetor should be next. What do you think?