Rottler SG9A, Руководство по эксплуатации и обслуживанию

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Selecting The Proper Pilot 9-1 SG9A Manual
www.rottlermfg.com
Chapter 9 Selection of the Pilots:
Choosing the right pilot will ensure the accuracy of the machining.
The pilot is selected according to the actual guide and not according to the original guide diameter or the valve
stem diameter.
Rottler Fixed Carbide Centralizing Pilots are manufactured from fine grain sintered tungsten carbide and are
ground to a very high degree of accuracy, straightness and surface finish - designed for a life time of precision
machining!
The part number of the pilot represents the actual diameter of the straight/parallel part of the pilot where the pilot
fits into the valve guide.
For example:
FCP0700 means that the diameter of the part of the pilot that goes into the valve guide is 7.00mm (0.2756”)
FCP1270 means that the diameter of the part of the pilot that goes into the valve guide is 12.70mm (0.5000”)
The pilot is the only link between the fixed part - the clamped cylinder head and the moving part - the air float
machine workhead. The centering and the machining accuracy depend on the use of the correct pilot. The pilot is
selected according to the actual valve guide and not according to the original guide diameter or the valve stem
diameter, the pilot is ALWAYS larger than the valve stem diameter.
Pilots are available in increments of .01mm (0.0004”). For practical purposes, it is best to select a pilot that is a
small amount less than the nominal size of the valve guide, approx .01mm (0.0004”) is recommended between the
pilot size and the valve guide nominal size. This clearance allows the pilot to enter all the guides in a cylinder head
as some valve guides may be smaller than their minimum tolerance.
Most new valve guides are manufactured to a nominal size such as 7mm or 11/32” and the valve stem diameters
are manufactured to be smaller than the nominal size to allow clearance for heat expansion of the valve stem when
the engine is operating. For example: a 7mm valve guide has an internal diameter of exactly 7.00mm (.2756”) The
valve stem diameter of the intake valve is 6.98mm (.2748”) and the exhaust is 6.96mm (.2740”). In order for the
pilot to fit most all valve guides, the first choice could be FCP0699 to give .01mm (0.0004”) clearance. If the valve
guide is used and has some wear, then the second choice of pilot could be FCP0700(0.2756”).
The pilot can also function as a GO-NO GO gage, in other words, if the pilot does not enter the valve guide, the
valve guide may be too small which could result in too little running clearance between the valve stem and valve
guide which could result in seizure and major engine failure!
Rottler makes 3 sizes of shanks of pilots:
1. 6.00mm (0.2362”) for small valves guides 6mm (0.236”) and below. The part number for these pilots is
FCPM.
2. 0.375” (9.52mm) for common size valve guides, 6-14mm (.236-.625”). The part number for these pilots is
FCP.
3. 20mm (0.7874mm) for large valve guides for SG80A machine. These pilots are made to order
specifications.
Below is an example of a 9.52mm 0.375” shank diameter pilot: