Usage:
.375" (9.53) Inside Diameter Grooved Valve Guides or .500" (12.7) Inside Diameter Valve Guides
The 1P7450 Honing Arrangement is used to size .375" (9.5) inside diameter grooved valve guides. These valves guides have a reduced clearance between the valve guide bore, and the valve stem, to provide more positive and controllable valve stem lubrication. They require a final sizing operation after they are assembled into the cylinder head. Tools available from the Caterpillar Parts Department for final sizing and inspection of the valve guides are: 1P7451 Valve Guide Honing Group, and 5P8615 Honing Oil. Use a brush from the 1P5580 Brush Group to thoroughly clean the valve guides after the honing operation.
The 5P7289 Mandrel (1), 5P7292 Adapter (2), 5P7291 Stone (3) and 5P7290 Sleeve (4) are used with the head and driver from the 1P7451 Valve Guide Honing Group to hone .500" (12.7) valve guides.
Sizing And Measuring Procedures
1 Install the valve guides into the cylinder head using the prescribed valve guide driver (see the Tool Guide).
2 Use 1P7458 Driver (1) and reamer (2) to presize the guide bore. See the chart below for the prescribed reamer.
NOTE: Later shoulderless grooved guides require sizing only if the size after installation is less than specified in the Service Manual. Use the 5P3536 Dial Bore Gauge Group to determine if honing or reaming is necessary.
3 Attach a drill to driver (1). Rotate the reamer at about 100 RPM.
NOTE: Use no lubricant during the reaming operation.
4 Use the 5P3536 Dial Bore Gauge Group (3) to measure the valve guide bore size. See the specific Service Manual for the correct inside diameter needed, to determine the amount of stock it will be necessary to remove.
5 To prepare for the honing operation, remove lug (4), if so equipped, from the wedge.
6 Snap the wedge into feed block (5) by pushing it straight in against the inclined surface of the feed block, compressing spring clip (6).
7 Attach adapter (7) to the head with bolts (8). Insert 1P7455 Mandrel (9) into the adapter with the wedge and stone retainer side by side as shown. Tighten screw (10). Place the correct stone (11) into the mandrel as shown. Install universal yoke (12) onto the head and attach the 3/8" (9.53) universal drive shank and the washer on the yoke.
8 The mandrel must be trued-in each time a new stone or mandrel is used. To do this, clamp the correct truing sleeve in a vise. Turn stone feed-up knob (13) clockwise until the stone touches the sleeve; then turn one complete turn. Hone as outlined in steps 10-12, however, use only a light coating of honing oil on the stone and shoes. Inspect the stone and shoes after several strokes. The entire length of the shoes and stone should show contact with the sleeve.
9 Dress down any high spots on the shoes using a file. Use either an abrasive stick or a diamond dresser to dress the stone. Repeat the truing operation if necessary.
10 After truing the new mandrel, stone (11), and shoes, place the mandrel into the valve guide. Turn stone feed-up knob (13) clockwise until the stone touches the bore. Then turn knob (13) one more complete turn to hold stone (11) firmly against the bore, as the stone automatically expands while honing. Release lever (14) retracts stone (11) so feed-up knob (13) does not need readjusting when the tool is withdrawn and reinserted into the guide bore.
11 It is important to have the stone pressure adjusted properly. Too much pressure results in excessive stone wear; too little pressure causes the stone to glaze and cease cutting. To increase the stone pressure, turn cutting pressure control (15) clockwise. Use a 150-400 RPM electric drill to drive the honing tool.
12 Turn the driving source on and stroke at a rate of 60 strokes per minute. For a long stroke, use a slower stroking speed. Stroke the full length of the guide, allowing the stone to extend through the guide by 1/4 to 1/2 the stone length. Use a continuous and ample flow of honing oil to insure accurate, fast honing and the desired finish.
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Turn the driving source off before removing the mandrel from the guide, to prevent whipping and possible damage to the guide or stone. If problems occur, refer to the topic, Troubleshooting, at the end of this instruction. |
13 Periodically make size checks with bore gauge (3). Check the guide at both ends and at various points in the bore.
Cleaning Procedure
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Thoroughly clean the valve guide bores after honing, to prevent valve seizure or rapid wear of the bore and valve stem. Use a brush and a strong detergent and water. Stroke each guide several times with a brush rotating at 1000 RPM. Thoroughly clean the head in an agitation type cleaning tank. |
Final Sizing And Inspection (.375" (9.5) Inside Diameter Valve Guides)
1 As a final check, the valve should slide freely in the guide with .0010"-.0015" (.0254-.0381) clearance.
NOTE: On D343, D346, D348 and D349 engines, it is permissible to use a maximum force of 20 pounds (9,1), and no oil, to install the valve.
Final Assembly
In final assembly, use SAE #30 oil for initial lubrication between the valve stem and valve guide bore.
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Failure to apply initial lubrication could result in valve seizure. |
Troubleshooting For General Usage Of The Hone
1. If the STONE WEARS TOO FAST, use more honing oil or use a harder stone.
2. If the STONE DOES NOT CUT, the stone is probably glazed. Increase cutting pressure. Shut off the honing oil for a few seconds. To sharpen the stone, stroke lightly with an abrasive dressing stick, or with a diamond stone dresser.
3. If the HOLE IS TAPERED, the stone is stroked too far out of the large end of the hole. Hone the work from the other end occasionally. This will keep the stone and mandrel true.
4. If the HOLE IS BELLMOUTHED -
a. Increase cutting pressure to get stability.
b. If bellmouth is only .0001" (0,003) or .0002" (0,005) worse than allowed, shorten the stone slightly on both ends.
c. If bellmouth is much worse than allowed, shorten stone and shoes to 1 1/2 times the bore length.
d. If bellmouth persists, shorten the stone still more, but do not shorten the shoes any further.
NOTE: Over-correction of bellmouth will lead to barrel shape.
5. If the HOLE IS BARREL SHAPED -
a. Increase stroke length.
b. Use a longer stone (if previously shortened) or shorten shoes slightly on both ends.
NOTE: Over-correction of barrel shape will lead to bellmouth.
6. If the HOLE IS OUT OF ROUND, the work is clamped too tightly. Use care when clamping thin walled sections. Do not use high cutting pressure on thin walled parts.