Table of Contents
Advertisement
67A
ENGINE—Service Information
16.
C o m p r e s s i o n R a t i o s
The compression ratios of the 370-C and 452-C engines as
shown below are greater than on the corresponding " B " series
engines
H . C . (Optional)
370-C—5.4 to 1
452-C—5.4 to 1
H . H . C . (Standard)
' 5.6 to 1
5.7 to 1
T h e increase in compression ratios necessitates a change in
the ignition timing, and the flywheel marks have been changed
accordingly.
That is, the I G / A marking on the 370-C and
452-C is 4° or approximately
in. ahead of center.
T h e compression ratio of the 370-C and 452-C engines can
be altered the same as in the " B " models by changing the
cylinder head gaskets. See Note 17.
17.
Interchangeability of 370 a n d 452 C y l i n d e r H e a d s
a n d G a s k e t s
T h e cylinder heads provided on 370-C and 452-C cars are
designated H H C and the lower compression ratios are ob-
tained by the use of special gaskets in the same way as on
370-B and 452-B cars. The " C " series head is interchangeable
on " A , " " B " and " C " series cars and only the " C " series
heads will be supplied by the Factory Parts Division for all
370 and 452 cars. The part numbers of the " C " series heads
are 1096172 for 370 cars and 1096173 for 452 cars.
These
heads can be identified by the letter " C " in a circle stamped
under the " H H C . "
O n later cars the " H H C " is eliminated
and the letter " C " in a circle is the only mark appearing.
T h e earlier type heads should not be used on " C " series
cars since the " C " series heads are of a considerably higher
compression ratio than the heads formerly provided for 370-A
and B and 452-A and B cars.
The use of these earlier heads
would necessitate a change of the distributor and the timing
marks on the flywheel. T h e H C ratio of the " C " series head
corresponds to the H H C ratio on " A " and " B " series cars and
the difference is equally great on L C and H C ratios of these
models.
T h e same gaskets are used on " C " model cars to obtain the
various compression ratios with the " C " series heads as with
the " H H C " heads used on " B " model cars and on some " A "
model cars.
In order to use the " C " series head on " A " or
" B " series cars, however, it has been necessary to provide
thicker gaskets under new part numbers so that the standard
" A " and " B " series L C , H C and H H C ratios can be main-
tained on these cars, regardless of the increased compression
of the " C " series heads.
It is important that the new (thicker)
gaskets, indicated in the table, be used when " C " series heads
are used on " A " or " B " series cars so it will not be necessary to
change the timing.
At the beginning of production on " A " series cars, separate
heads, machined to the required thickness, were used to
provide H C and L C ratios.
The ratios of these heads cannot
be changed to any of the standard ratios by the use of special
gaskets.
Since a number of these heads are still in use, it is
important that the heads be carefully identified before at-
tempting to change the ratio by the use of the special gaskets.
Since any one of several heads have been used interchange-
ably on " A " and " B " series cars, it may sometimes happen
that the heads on the right and left-hand blocks of a car differ
and in such cases different gaskets will be required for these
heads to maintain the same ratio for both banks of cylinders.
It is therefore important that the identity of b o t h heads be
determined when replacing gaskets.
Ordinarily, if the mark-
ings on both heads are similar, it may be assumed that both
heads are of the same type.
Table of Cylinder Heads and Gaskets
Series W h e r e U s e d
C y l i n d e r H e a d
P a r t N u m b e r
Identif c a t i o n
Part N u m b e r <
ratios o r i g i n a l l
>f gasket r e q u i
y specified for ^
red t o o b t a i n
arious models
Series W h e r e U s e d
C y l i n d e r H e a d
P a r t N u m b e r
M a r k i n g
T h i c k n e s s
L C r a t i o
H C r a t i o
H H C ratio
370-A and 370-B
1091383f
L C
C 5 II
' 3 2
889361
(4.9 to 1)
*
*
370-A and 370-B
1091440f
H C
5 A "
*
889361
(5.2 to 1)
*
370-A and 370-B
1091133f
H H C
5 T V
894392
(4.9 to 1)
894339
(5.1 to 1)
889361
(5.4 to 1)
370-A and 370-B
1096172
5"
889408
(4.9 to 1)
894392
(5.1 to 1)
894339
(5.4 to 1)
370-C
1096172
5"
894392
(5.1 to 1)
894339
(5.4 to 1)
889361
(5.6 to 1)
452-A and 452-B
1090245f
B or L C
5
A"
881027
(4.9 to 1)
*
*
452-A and 452-B
1090486f
H C
J 3 2
*
881027
(5.1 to 1)
*
452-A and 452-B
1090240f
H H C
896503
(4.9 to 1)
896450
(5.1 to 1)
881027
(5.4 to 1)
452-A and 452-B
1096173
©
°
r
®
883608
(4.9 to 1)
883609
(5.1 to 1)
896450
(5.4 to 1)
452-C
1096173
H
H
C
o r
@
©
4-5-7»
^ 64
896503
(5.1 to 1)
896450
(5.4 to 1)
881027
(5.7 to 1)
f N o longer furnished for service.
*Not available with cylinder head indicated.
August 1933
Advertisement
Chapters
Table of Contents
