Unmatched Performance & Durability since 1983
JPrecision specializes in high performance machining of engines components. We let your local qualified mechanics to do the final assembly. Contact your local dealer for more details.
It only takes one pass on a dyne or a quick ride on an open road to fully appreciate the exceptional performance offered by JPrecision heads. Cylinder heads modified and upgraded by JPrecision are simply the most powerful and reliable that money can buy.
Unmatched Performance & Durability since 1983
JPrecision specializes in high performance machining of engines components. We let your local qualified mechanics to do the final assembly. Contact your local dealer for more details.
It only takes one pass on a dyne or a quick ride on an open road to fully appreciate the exceptional performance offered by JPrecision heads. Cylinder heads modified and upgraded by JPrecision are simply the most powerful and reliable that money can buy.
Adrenaline and Satisfaction Guaranteed!
STAGE II
For stock castings
This Stage features our upgraded intake and exhaust port design and is CNC ported for optimal precision and repeatability. We use only top quality components from the company AV&V™ for outstanding reliability. This is a perfect performance upgrade for your street performance needs.
It features a 1.700 inlet opening, and the chamber is left in its natural state, making this head a perfect fit for any motor combination from 88” to 107”.
STAGE IIB – High Torque Heads
For stock & aftermarket castings
Same as Stage II except for the intake port which is redesigned and raised by welding to increase velocity, allowing for a crisper throttle response.
- The chamber is CNC contoured and finished by hand to a satin finish.
- Great upgrade for all TC heads, including SE, S&S and other aftermarket heads.
STAGE IIIB – High Torque Heads
For stock castings
Same as stage II plus we install 1.940″ intake valves & oversize seats and increase the intake port area, resulting in peak horsepower increase.
STAGE IVB – High Torque Heads
For stock castings
Ultimate modification for your factory casting. We install 2.000″ intake & 1.580″ exhaust valves and modify the ports accordingly. Makes the most power from bigger throttle body or carbs. We recommend a manifold/ throttle body with 1.800″ runners to take full advantage of these heads.
STAGE V – High Torque Heads
For stock castings
We install 2.150″ intake & 1.650″ exhaust valves and modify the ports accordingly. Intake valve angle is modified and rocker arm geometry is corrected
- Designed for 131” / 4,250” bore engines
- Must be used with SE 120R Hurricane oval port manifold
- Up to 175 rear wheel HP potentiel.
HEAD WORK OPTIONS
MANIFOLD PORTING
We port the manifold to optimize the airflow and to achieve a better fuel atomization through our proprietary finishing process.
COMPRESSION RELEASE VALVES
We machine the heads to install the compression release valves in line with the spark plug for an easier access and a better look. We also machine heads for automatic compression release valves.
PISTON VALVE POCKETS MACHINING
We machine the pistons to re-establish a correct valves to piston clearance after installation of higher lift cams, larger valves or head shaving. (Usually, all TC cast pistons require clearancing)