Engine builder Mick Gray is putting the final touches on the tune-up before we fire it up.
Last time we had Project 505 on the dyno was for the September 2007 issue of Mopar Muscle when we were testing the new Holley Ultra HP carbs. During that test session, we saw 738 horsepower from the combination of a big flat-tappet cam and a Holley 1050 Dominator carb. Encouraged by the results from that dyno test, we picked up the phone and ordered a pallet load of parts from Jesel, Comp, and Indy in a quest for 800 hp.
The Test Mule
Project 505 was originally built for the "Modern Max Wedge" article that ran in the August 2007 issue of Mopar Muscle. It's based on a thick-wall, 1977 production 440 block with a 4.250-inch stroke crankshaft, 6.800-inch long Chevy rods, and forged Diamond Racing pistons with 13.5:1 compression ratio. The cylinder heads are Indy EZ units that were CNC ported by Modern Cylinder Head. The heads flowed a little over 360 cfm at .700-inch lift when tested by our buddy Dwayne Porter at Porter Racing Heads. Interestingly enough, the heads also flowed 360 cfm when tested at .750-inch lift as well as .800-inch lift, so valve lift above .700 inches does not increase airflow on these heads.
The 505 short-block has stayed the same since the last round of testing. The 4.250 stroke
In earlier dyno tests, this motor made 625 horsepower with a Mopar Performance cross-ram and 738 horsepower with the single Dominator carburetor installed, so we knew the raw potential was there to hit our 800 horsepower goal. Our plan was to change over to a roller cam and to install the larger 440-3X intake from Indy, as well as the Jesel rocker arms, Jesel belt drive, and a Jesel distributor. We filled the pan with 9 quarts of Joe Gibb's break-in oil since the motor is still fairly fresh, and we used our typical dyno combination of a remote screen type oil filter and a reverse flow Meziere electric water pump.
Cam and Valvetrain Parts
The cam that we used for the previous Holley Ultra dyno test was the MM 305S-10 camshaft from Comp Cams. The MM 305 camshaft is one of the largest flat tappet cams in the Comp catalog, but our dyno simulation program told us that we would need a roller cam with at least .800-inch of lift to reach the 800 horsepower mark. We didn't want to increase the duration too much since our short-block wasn't designed for high rpm operation, so we worked with an engineer at Comp to find a camshaft that had the same basic duration as the MM305, but with a lot more lift. What we ended up with was a custom cam with .275/.282-degrees of duration at .050-inch, and lift numbers of .830/.782-inch respectively. This cam is part number 1722B/1850B R110 for those who might want to duplicate this effort.
The new valvetrain components included a Comp roller cam and lifters, Jesel rocker arms, P
With a little over .800-inch valve lift to control, we knew we needed a fairly stout valvespring, so we took a look at the PSI line of springs. After discussing a few of the choices available, we settled on the PSI 1246 spring, which is a large diameter triple spring designed to be set up at 2.00 inches installed height. The specifications on this 1246 spring are 300 pounds of force on the seat and 890 pounds over the nose. We might have gotten by with a little less spring force, but on a motor like this we prefer to err on the conservative side so that we have some extra margin on hand in case we swap cams or decide to run more rpm.
In order to achieve the .800-inch lift that we were looking for, the rocker arm ratio needed to be increased from the stock 1.5 to a much more aggressive 1.7. With a .488-inch-lobe lift cam, the higher-ratio rocker arm gave us a gross valve lift of .830-inch, where a 1.50 rocker arm would have only yielded .732-inch lift. It is possible to buy standard shaft-type rocker arms in a 1.70 ratio, but the valvespring load required for these super high lift cams is so high that the standard shaft rocker arms start to have durability issues. So after looking into several different solutions, we decided to take the plunge and purchased a set of Jesel rocker arms. This was just the beginning of the adventure, though, since Jesel didn't have a set of rocker arms designed for the Indy EZ head.
The existing rocker shaft stands have to be machined away in order to mount the new stand
Jesel only sells rocker arm kits with the high-offset intake rocker arm as shown on the le
Once all the machine work was finished up, we bench tested the new valvetrain to make sure
It took some work to get the Jesel hardware mounted on our Indy heads, but once we had it
Our initial mockup of the Jesel distributor showed that we were going to have a major clea
The combination that we ended up using had the Jesel distributor mounted on a custom brack