1 The Mopar Performance P4876337 intake manifold surprised us by squeaking out a little m
Last time we had Project 505 on the dyno was the June 2010 issue of Mopar Muscle when we modified our Indy EZ heads for Jesel rocker arms. During that round of dyno testing we saw a peak of 805 horsepower, but we also encountered some valvetrain oiling issues. For this round of testing we set out to solve the oiling issue as well as try a new cam profile and different rocker arms. This time, we're running the Max-Wedge Super Victor intake with a BLP-modified Dominator carburetor. Finally, one thing that we have wanted to try for a long time is a dry-sump oiling setup. We couldn't find much in the way of store bought parts, so we got busy and fabricated a low-buck way to turn Project 505 into a dry-sump lubed engine.
Project 505 is based on a stock 440 block with a 4.250-inch stroke crankshaft from 440Source, a set of 6.800-inch long rods from SCAT, and forged pistons from Diamond Racing. The pistons have small 5cc domes that yield a compression ratio of 13.5:1 when combined with the 75cc chambers in the Indy EZ heads.
2 Increasing the intake rocker arm ratio from 1.70 to 1.85 added 10 horsepower by itself.
This engine has seen a lot of testing duty over the last couple of years so it is equipped with dyno friendly parts such as a Jesel beltdrive (for ease of cam timing), an electric water pump, 2-inch dyno headers, and a belt-driven distributor. We left all of these support pieces in place for this round of dyno testing but we did install cylinder head studs rather than re-use our existing head bolts. ARP makes several very high-quality cylinder head stud kits for the big-block Mopar engine so we gave them a call for one of their Indy kits. The Indy cylinder heads require a special kit because two studs on each bank need to be slightly longer than the other studs. For the exhaust side, we purchased some special head studs from ARP that were just 2.725 inches long. We needed the special studs to gain clearance for the header flanges because the exhaust ports on the EZ head are in a fairly low position. You would not need these shorter studs with raised exhaust ports.
Camshaft and Valvetrain
The Chrysler big-block motor was originally produced with 1.50 ratio rocker arms, but engine builders have long been running higher-ratio rocker arms in an effort to make additional power. Following that trend, we converted these EZ heads over to 1.70 ratio Jesel rocker arms last year when we installed a roller cam.
3 Since many Mopar cams are designed to work with only 1.50 ratio rocker arms, we worked
One of the many advantages of the Jesel rocker arm system is that they have a complete selection of rocker arm ratios, ranging from 1.55 to 1.85. For this round of testing we consulted with Mike Jones at Jones Cam Designs and decided to go with a ratio of 1.85 on the intakes and 1.70 on the exhaust. Mike's advice on the subject is that higher ratio rocker arms can provide the valve motion that the engine needs without compromising the base circle on the camshaft.
The camshaft that Mike designed for us was part number R80393-82401. This cam has a fairly mild lobe shape with only .393-inch lobe lift and duration of 266 degrees at .050-inch lift. When combined with the 1.85 rocker arm ratio, this cam profile gave us .707 net-inch lift on the intake side. The exhaust lobes have 272 degrees of duration at .050-inch and lobe lift of .401-inch for a net valve lift of .661 inch.
We matched the camshaft with a set of 26097-16 valvesprings from Comp Cams as well as a set of their tool-steel valvespring retainers. These springs are made from an enhanced processed material, and are only 1.539-inches in diameter, which leaves plenty of room around the rocker arms. We set the springs up with 220 pounds of pressure on the seat and 560 pounds over the nose.