When a four stroke internal combustion engine cylinder head is flow tested, it is often required that the flow testing is performed at various valve lifts, or heights. These valve heights are often done at every 0.1" or even at every 0.05" lift increments. Some method of locating the valve at a precise height is required while the flow rates are measured.
These 2 items could very well be the
method for positioning and measuring a valve height for flow testing cylinder heads.
The vice-grip / dial indicator setup can be found at many discount tool stores. The clips can be found at most hardware or home centers in the hardware department.
It does take a little practice but locating the valve using nothing more than your fingers is not as difficult as it looks. A clip is installed on the valve stem to keep it from falling through the valve guide. The dial indicator shows you the valve height.
Resting your fingers on top of the valve guide while you grip the valve stem helps steady your hand and the valve.
What can go wrong with this setup?
If you do not want to blemish aluminum surfaces or you can't find a suitable surface to clamp the vice-grip onto, try inserting a bolt onto one of the many threaded holes in your test piece and clamp onto the bolt. Or clamp onto your bench surface, or place a heavy object next to your test piece and clamp onto the object.
Valve Positioning and Measurement
Always make sure that everyone in your work area is wearing eye protection when working with springs!
A very popular method of valve positioning and measurement is by attaching a long coupling nut to a dial gauge with a bolt threaded into the top end to move the dial gauge stem, which moves the valve. This apparatus requires a bit of skill to construct, and the hardware that locates the assembly over the valve is subject to flex, altering your true readings on the dial gauge.
This method requires the use of a spring and retainer. The stand is threaded into the valve's rocker arm bolt hole, or onto a rocker stud using a coupler nut.
3/8" - 16 threaded rod and a dial gauge holder clamp are used to construct a stand for the modified dial gauge, which threads into the valve's rocker bolt hole or stud. Use a 5/16"-18 to 3/8"-16 coupler reducer nut for 5/16" rocker bolt holes.
A 5/16"-18 by 1 3/4" long coupler nut can be attached to a dial gauge, and the dial gauge stem positioned with a bolt threaded into the top end of the coupler nut. Some gauges have a wider bezel, as shown on the left, which requires clearance on the coupler nut. The coupler nut on the left was epoxied onto the gauge, the coupler on the right was attached with set screws.
Here is a very simple, and accurate method to position and measure valves. This only works on valves that are not canted, or angled to the length of the head. A metal bar has a small piece of square brass tubing attached with a roll pin or small bolt. The roll pin or bolt should be much smaller than the inside of the square tube, so that the square tube can conform to the top of the valve stem easily.