Engine Valve Specifications
You can view and save copies of this drawing in Adobe Acrobat® (PDF)
Overall Length (A):
The total length of the valve, as
Same Length (T):
Our remanufacturing process
allows us to provide you with valve sets that are the same length (as measured from the
face to the tip) to help you adjust for heads that may have been decked or milled. This
eliminates problems associated with different valve lengths, such as improper rocker arm
geometry or improper lifter preload.
Pre Grind Length Before Chrome (R):
valves have their stems pre-ground undersize in preparation for the hard chrome plating.
This ensures that you have at least 0.0015 in. of hard chrome per per side after
electroplating and finish grinding. Proper length must be maintained for plating purposes.
Pre Grind Length After Chrome (C):
plating, embrittlement baking and adhesion testing, each plated valve is pre-ground. This
step, although more time consuming, brings the valve close to its finished size, allowing
us to control our finish grinding operation more accurately. Proper length must be
maintained for finish grind purposes.
Minimum Chrome Length (Q):
The minimum length of
hard chromium applied to the valve stem as measured from the valve tip.
Finish Grind Length (B):
The minimum length, as
measured from the valve tip, for which we maintain our finish grinding specifications of
surface finish, stem diameter, and lobing.
Minimum Clean Up (P):
The absolute minimum finish
ground stem length.
Minimum Margin (L):
The minimum length of the head
at its major O.D. (lip thickness) may be affected by face grinding and is therefore
monitored as needed.
Head Diameter (J):
The major O.D. of the valve
Face Angle (K):
The face is finished to the exact
angle you need to ensure proper seating with the seat.
Original Stem Diameter (F):
The outer diameter of
the stem as received.
When specified, the finished diameter
of the valve may be larger at the tip end and smaller at the head end very accurately.
Typically taper is only provided on certain exhaust valves to allow for thermal expansion
at the head end.
Finish Grind Diameter (H):
The final stem diameter
that is achieved throughout the finish grind length.
Pre Grind Diameter After Chrome (I):
stem diameter that the valve is ground to following hard chrome plating. This diameter is
maintained throughout the entire Pre Grind Length After Chrome.
Plated Diameter (G):
As the valve stems are hard
chrome plated, their diameters are monitored to ensure that the proper thickness of chrome
Tip To Chrome (D):
The length of valve that is not
plated such that the keeper grooves are not affected.
Minimum Tip Hardness (U):
We verify the tip
hardness on 100% of all exhaust valves or any valve known to have a history with hardness
problems. Any valve not meeting your minimum specification is rejected.
Pre Grind Diameter Before Chrome (S):
stem diameter that the valve is ground to prior to hard chrome plating. This diameter is
maintained throughout the entire Pre Grind Length Before Chrome.
Stem Type (M):
Refers to the keeper groove style.
The groove area is cleaned and inspected and is otherwise unchanged from the as-received
condition. Grooves are not plated or repaired in any way. Any part found to have worn
grooves is rejected.