CYLINDER HEAD - CONTINUED
Never vacuum test cylinder head with injectors installed. Installation of injectors while
head is removed from block could cause misalinement of valves in valve seat area and
result in leakage during testing which would not necessarily occur during actual engine
Steps 60 thru 64 are typical for all valves. (Vacuum tester operating instructions are
provided with tester.)
60. Cylinder head (5)
Using ST-417, ST-417-A, or ST-1257
vacuum testers, hold vacuum cup (13) over
head of valve and seat flat on cylinder
head surface surrounding valve.
Vacuum pump (14)
Operate vacuum pump until hand (15)
on vacuum gage (16) reaches 18 to
25 inches vacuum, then close shutoff
valve (17) and stop pump.
Start timing when hand on gage reaches
Stop timing when hand on gage reaches
If elapsed time is less than 10 sec-
onds, valve seat is unsatisfactory.
T A 2 4 2 4 8 1