SPECIAL MODIFICATIONS FOR C8AX-6250-D CAM
Because of the extreme 0.600" lift of this cam, a spring bind condition will result if stock parts are used. You can solve this problem by installing special high rpm performance push rods, springs, retainers, keepers and solid tappets (available from several sources such as Holman-Moody, Crane or Iskenderian) The tappets and push rods are lightweight, the springs are made of stiffer, smaller diameter wire so they can be compressed more, the keepers are specially hardened, and the retainers have been machined with an offset that allows about 0.100" additional valve movement without the spring bottoming out. The spring height and pressure should be set according to the specifications supplied with the parts.
A Piston-To-Valve Clearance check is always a good idea with high performance setups. This is especially important here because of the extreme high lift of these cams.
STAGE 4 (Revisited, One More Time)
To Add Some Tough Muscle Inside
428 CJ HEADS AND POP-UP PISTONS
This step was optional with 390 Controller Kit, but is mandatory with the Dominator Kit. Install 428 Cobra Jet CYLINDER HEADS C8OZ-6049.K (2 req'd). Do not mill them to decrease combustion chamber volume, so as to increase compression ratio to 10.7:1. Instead, use POPUP PISTONS C9OZ-6108-Y R.H. (4 req'd) and C9OZ-6109-A L.H. (4 req'd), which use RINGS C1AZ-6148.A. (Note: These pistons will not be available until August, 1969.) Don't use the special, thinner steel head gaskets that were installed with "milled" heads. Instead, put in the regular HEAD GASKETS C8AZ.6051-A (2 req'd) that come with the 428 heads.
LIGHTWEIGHT VALVES
Lightweight valves will enable you to take full advantage of the breathing capabilities of the 428 heads and the highrevability of the mechanical cam and valve train pieces. Install lightweight, hollow stem INTAKE VALVES C8AX-6507-A (8 req'd) and lightweight, hollow stem, sodium filled EXHAUST VALVES C8AX-6505-A. Head diameters are identical to the stock 428 valves; 2.097"-intake and 1.660"-exhaust. Both are easily identifiable from standard 428 CJ valves, because both lightweight valves are chrome plated.
STRONGER 427 CONNECTING ROD
With all that high revving your 390 is now capable of, a little insurance is in order downstairs. Hang your lower-end together with 427 CONNECTING RODS C5AZ-6200-D (8 req'd) These "LeMans" type rods feature cap screws instead of the usual nut and bolt design to button the caps to the rod for unusually high rpm operation. (Note: 0.010" must be ground off each side of journal end of 427 rod to fit in 390 bore.) Use ROD BEARINGS C5AZ-6211-G for added performance durability. Installation of 427 rod necessitate rebalancing the engine since they do not weigh the same as the stock 390 rods.
DOMINATOR KIT Total Incremental HP Increase 119
Well, just look what a few 427 and 428 pieces do for your 390 torque and horsepower ratings. That's what we call some Muscle. Your 390 will never be the same. Use extra care when you hang it all together and get set to turn an extra low E.T.