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Page:Popular Science Monthly Volume 89.djvu/618

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604

Removing and Applying Valve- Stem Guides by Pressure

AFTER an autoniol^iic engine has . been in use for a time, the guides or hearings for the valve-stems depreciate to such an extent that tiiere isappreciable looseness between the valve and its bear-

��Popular Science Monthly

���PRESSURE NUT- BUSHING

VALVE CHAMBER CAP

-PRESSURE BOLT

TE.N5I0N BOLT

VALVE SEAT

WATER JACKET

SPACE CLNTERING PLUG

��REMOVABLE VALVE STEM GUIDE

���Pushing the valve-stem guide out of its place by screwing down a pressure bolt

ing. This not only results in noisy action but also interferes with proper engine operation, because air leaks in on the suction stroke through the inlet valve guides, dilutes the mixture and makes for unsteady engine operation at low speeds. On well designed engines, the valve-stem guides arc removable and new ones can be easily inserted in place of the worn members.

A simple and effective method of rc- mcning is illustrated at A. The valve- chamber cap carrying the spark-plug is used as a basis for the device. A bushing to replace the spark-plug is screwed into the cap, this being tapped out for as large a bolt as possible. If the spark-plugs are ^-in. standard pijie size, a i^^-in. or 7/16-in. bolt can be used to advantage. The bushing is easily forced out by pressure obtained by screwing down the bolt. This is superior to the ordinary method of driving the bushings out with a drift, because the seating or casting may be damaged by a careless blow of the hanuner.

The method of applying the new guide is onlliiied at B in the accompanying illustration. A long boll, the size of the valve-stem is used as a tension screw, this passing through a piece of slcel or

��iron bar resting on the valve-cap. Pres- sure applied against the guide by eithci the top or bottom nut will draw the bushing in place in the c\'linder-casting without injuring it. The usual methotl followed of driving the bushing in is apt to result in breaking that member. While a lead or copper hammer is not .so apt to mar the surface as the steel ham- mers are, still there is always danger of breaking the bushings. This is entirely eliminated by the forcing in process.

��Quickly Adjustable Automobile Fan- Belt Fasteners

ANKW type of automobile fan-belt fastener has just been brought out. It is quickly attached, adjusted or repaired. .The fastener consists of two metal parts, each attached to one end of the belt by means of three small brads. One metal part, the male, has two curved hooks \\ hich are slipped into two corresponding slots cut in the female half to make the belt continuous.

The fasteners are used with a special fabric belt and may be attached in a few minutes by means of the small brads. If the belt works loose on the pulleys, it may l)e taken off in a few seconds simi)ly by unhooking the fasteners, whereas with a laced leather belt this takes several minutes and is a disagreeable job if one has to lean over a hot engine that has been running for several hours. To adjust the loose belt, the three brads of one of the fasteners must be removed, the fastener itself moved back a sliort

���Any length of belt can be made up and adjusted by the use of the fasteners

distance on the belt and the brads jmslu'd through the belt at otlu'r points.

Tlu' fasti'ners are made of c-old rcilKii steel, the hooks being lieat-tri-ated but not made brittle, while the female fastener is left soft.

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