|
The CV-1 represents
a clean sheet redesign of the conventional Pontiac cylinder head. So unique are some of its features, they
are patented. Perhaps
the most obvious feature are the canted valves. The CV-1 design is unlike other canted designs because
the valve heads are horizontal in the chamber. This feature, in combination with the large amount of valve
roll, reduces the amount of valve to valve clearance required, permitting the use of larger valves in the same bore
size. The intake valve placement aligns it with the stock cylinder scallop on most pontiac blocks for improved
low lift flow. From a performance perspective, canted valves offer improved breathing over a typical inline
valve design, here's why: As
shown in Figure 1, the valve heads are tilted to the inside. As they open, the path projects them toward
the middle of the cylinder which unshrouds the valve by moving it away from the cylinder wall. This allows the use of larger
valves with improved flow in the same bore size. The CV-1 is designed with the maximum amount of valve cant angle possible
for the best unshrouding effect and airflow.
|
|
| |
|
Next, the
intake port layout was redesigned to eliminate pushrod restrictions as shown in Figure 2. The original Pontiac intake port
layout is good for stock displacement moderate performance. However, the stock design limits port size for larger
displacements and competition engines without expensive offset shaft rockers and lifters. The CV-1 design spreads
out the intake ports allowing larger port sizes without requiring expensive offset valvetrain. What makes
the CV-1 affordable is the ability to use low price off the shelf components. What makes
the CV-1 valvetrain superior to offset shaft designs is the "balanced valvetrain" which eliminates rocker arm
side loading. The intake pushrods on a typical .700" offset shaft system with performance valve springs can exert
over 100lbs of side load against each intake rocker arm! With 8 intake valves, thats 800lbs of extra vavletrain load which
eats up crankshaft horsepower. The CV-1 rocker arms are canted at the same angle as the pushrods as shown in Figure
3, which eliminates side load and increases horsepower. The large
port (285cc as cast) option gives increased port size (3.2"csa as cast) matching the requirements of 428-535ci
performance applications with correct cam and gearing. If supersize (>535ci) hi rpm breathing is needed, up to 2.35"
intake valves can be installed. Additional porting available through Roland Racing can then achieve the required
airflow needs.
|
Figure 2
Figure 3
|
| |
|
|
The chamber has been updated with dual quench technology.
This efficient chamber is designed with opposing squish pads for uniform mixing as shown in Figure 4. The increased turbulence
enhances flame front travel for better detonation resistance, allowing the use of higher compression ratios. Spark plug location
is centralized to equalize flame fronts for complete combustion, and reduce required ignition advance.
|
Figure 4
|
|
The exhaust flange is traditional Pontiac Ram Air round
port as shown in Figure 5. The location of the flange has been raised approximately 3/8". 2" primary
tube headers are recommended for most CV-1 applications. The "convertible"
exhaust option allows the exterior portion of the port to be removed as shown in Figure 6. This modification can
be performed at the time of sale, or later at a competent machine shop. If desired, instructions can be obtained apon request. The convertible exhaust option simplifies header fabrication and offers a performance improvement
through straighter, more efficient header design. Convertible exhaust flanges (shown in yellow) with or without starter
tubes are available through Roland Racing.
|
Figure 5
|
| |
Figure 6
|
