Bulletin Subject: Servicing Cast Iron Sleeves, Part No. 8N-6055-B

As announced in Service Bulletin No. 190, dated December 5, 1951, cast iron

sleeves were incorporated in production, effective with Tractor Serial No.

8N-433578.

Parts and Accessories Bulletin No. 202, dated January 2, 1952, announced the

availability of the subject sleeve as a service item. In Attachment #5,

instructions outline the correct procedure for servicing these sleeves in the

field, and should be followed in detail to obtain satisfactory results.

Bulletin Subject: Engine Valve Clearance

Insufficient clearance between the tappet and the valve stem is one of the

primary causes for valve burning. However, particles of carbon that lodge

between the valve face and the valve seat are sometimes responsible for what

appears to be insufficient valve clearance. The carbon does not allow the

valves to completely close and in turn excessive heat is retained at the

valve face which cannot be dissipated without contacting the valve seat.

When adjusting the valve tappets for proper clearances, as given in Service

Bulletin No. 179, a uniform method of procedure is of extreme importance.

The proper cold clearance for setting exhaust valves is .014 to .016 end for

intake valves, .0l0 to .012.

In order to specify a uniform method of checking valve clearance on the tractor,

the following chart is suggested:

VALVES OPEN

#1 Exhaust and 3 Intake

#1 Intake and 2 Exhaust

#2 Intake and 4 Exhaust

#3 Exhaust and 4 Intake

VALVES TO BE CHECKED

#2 Intake and 4 Exhaust

#3 Exhaust and 4 Intake

#1 Exhaust and 3 Intake

#1 Intake and 2 Exhaust

Correct adjustment of valve clearance may be obtained only if the valves indicated

in the above chart are in full open position and with the engine at room tempera-

ture (approximately 70° F.).

When checking valve clearance, it cannot be overemphasized that the tappet should

be against the flat of the cam and not on the cam ramp. In some cases it has

been found that the tippet actually is not in contact with the cam when valve

clearances ere set, thus causing excessive clearance.

Bulletin Subject: Oversize Pistons and Ring Sets

Parts and Accessories Bulletin No. 267, dated December 1, 1952, announced the

availability of oversized pistons and ring sets. These parts may only be used

in 8N tractors which incorporate the cast iron sleeve, Part No. 8N-6055-B, as

it is necessary to rebore and hone the sleeves to obtain the recommended piston

fit to cylinder bore of 5 - 10 pounds pull, using a .002 x .50 ribbon pull scale.

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