Allis-Chalmers HD-4 - Valve Tappet Clearance

VALVE TAPPET CLEARANCE
Diesel - .015" Intake - • 015" exhaust (Hot)
Correct clearance between valve sterns and
rocker arms should be maintained at all thnes.
The engine must be heated to its normal operating
temperature before making the adjustment.
Turn the valve adjusting SCrew until there is the
proper clearance between valve ste:rns and rocker
arms when measured with a feeler gauge. Re-
check clearance.
From front of engine to rear valves are located
as follows:
# I Intake - Exha us t
*2 Exhaust - Intake
If 3 Intake - Exha us t
1/4 Exhaust - Intake
To adjust clearance, first rotate engine until
No.4 exhaust valve closes~ and adjust both
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valves on No. 1 cylinder.. Second, rotate engine
until No. 2 exhaust valve closes and adjust both
valves on No .. 3 cylinder. Third, rotate engine
until No. 1 exhaust valve close s and adjust both
valves on No. 4 cylinder. Fourth, rotate engine
until No. 3 exhaust valve closes and adjust both
valves on No* 2 cylinder ..
This method of adjusting tappets eliminates the
necessity of adjusting one valve on a cylinder,
then having a go back to the Same cylinder to
adjust the other valve, therefore saving time
and simplifying the procedure. Starting with
No. 1 cylinder and following the £iring order of
the engine, only four !tOne Halfl! turns of the
engine are necessary for a complete job of ad-
justing valves.
l...ack of co:rnpression because of leaky valves may
be caused by either insufficient clearance between
rocker arms and valve sterns; or by carbon or
gummy substance on the valve stell1S oX' seats,
preventing the valves frorn closing.