On the Dyno
We needed 2 inches of installed...
We needed 2 inches of installed height for the big PSI valvesprings. In order to get that much installed height and still clear the rocker arms, we had to use some Manley +.100-inch retainers and +.050-inch locks.
There were a few snow flakes blowing around the truck when we unloaded the motor at Gray's Automotive in Tigard, Oregon. With the temperature reading in the mid '30s, we knew that the motor would be capable of making plenty of raw power.
The big 1050 Dominator was very rich off idle the last time we ran it, so this time we decided to get serious with the jetting. The stock jet size in the intermediate circuit on this particular Dominator was a 46 jet, which we dropped down 26 jet sizes to a 20 jet. Changing the jet size by 26 steps is a very drastic move but it seemed to work since the A/F ratio stayed right around 12.5 throughout the entire dyno pull. We left the main jets at the stock 88 size to start with, but we eventually increased the main jets to 89s in all four corners in order to drop the EGT reading down a bit. We never had to change those intermediate jets, so our 26 jet-size change evidently worked.
It is important to use a tapered...
It is important to use a tapered pushrod end to clear the body of the rocker arm. We found that Smith Brothers had a special end for their pushrods that works with the Jesel rocker arms.
Quite frankly, it bothered us to run a carburetor with the jetting so far removed from stock, so we called Holley engineering to discuss the issue with them. Our contact at Holley walked us through some other potential solutions to the off-idle rich condition that we had seen such as opening up the air bleeds, making sure the power valves weren't open, and dialing in the idle circuit properly. We'll put that information on carb tuning to work next time we have this Dominator back on the dyno, but for this test we made due with the leaned out intermediate circuit. Since the A/F ratio looked good on the wide band and since the spark plugs looked good, we went ahead and made some full throttle dyno pulls.
The best number we saw during the testing was 805 horsepower at 6,400 rpm, so we achieved our goal of hitting 800 horsepower with the EZ heads. Our theory on the cam timing seemed to be confirmed when we looked back at the previous test results. In earlier testing, we saw a peak horsepower reading of 625 at 6,300 rpm with the cross-ram, 705 at 6,100 rpm with the Indy ram intake, and 738 at 6,400 rpm with the Indy 440-3 intake. So this motor, with these heads and cam timing, makes the most power right around 6,400 rpm, regardless of the intake manifold or carburetor.
When you use a beltdriven...
When you use a beltdriven distributor, there needs to be a plug installed in the stock distributor location. We couldn't find anyone who sold these plugs, so once again, we had the machine shop make us a custom part.
After the first round of dyno tests, we pulled the valve covers to run the lash and noticed that some of the pushrod ends were turning blue from heat, so we decided to call it a day. We knew that the motor had plenty of potential still left in it since we hadn't had any time to adjust ignition or cam timing. Typically, there is another 15 or 20 horsepower to be found during a dyno session by tweaking the timing and playing with the spark gap and carburetor spacers.
Watching a motor crank out 800 horsepower is a lot of fun, but that much power in a stock block with stock main caps is living right on the edge, so we chose to shut things down rather than push our luck. We had the feeling that if we kept making those 800 horsepower pulls that we would get stuck with mop duty before the day was finished and that didn't sound too attractive to us. But even without taking the time to fully flog this particular combination, we did learn some neat stuff. People had told us that the EZ heads weren't capable of making 800 horsepower and we busted that myth. We had also been told that there wasn't any point in running .800-inch lift in an EZ head since the head flow flattened out above .650-inch lift, but it appears that the motor actually can use that extra lift. Now it might be true that there are easier ways to make 800 horsepower from a 505 Mopar, but we used the parts that we had on hand and got it done our way. If you have an 800 horsepower combination that you think is better than this one, then drop us a line and let us know how you did it.
The Indy 440-3X intake received...
The Indy 440-3X intake received a little attention in the plenum area. Basically, we were just trying to get a nice taper from the carb spacer to the plenum without any big steps or ledges. We didn't port match the intake even though we really should have.
With the engine mounted on...
With the engine mounted on the dyno, you can see a few more details such as the 2x32-inch Stahl dyno headers, the oil lines for the valve cover oilers, and the Wilson carb spacer.
Since this is a stock block...
Since this is a stock block without lifter bushings, we had to use valve cover oiling to provide oil to the valvetrain. We evidently didn't quite have the oiling system dialed in perfectly since the pushrod ends began to show signs of excessive heat after just a few pulls. We'll have to correct this issue before leaning on this engine again.