6-1
ENGINE MECHANICAL
CONTENTS OF THIS SECTION
SIX CYLINDER ENGINE
V - 8 ENGINE
GENERAL DESCRIPTION
TEMPEST AND FIREBIRD ENGINES
The Pontiac Tempest and Firebird uses a 250 cubic
inch inline overhead camshaft six-cylinder engine as
standard equipment. This engine has a 3 7/8" bore
and 3 17/32" stroke with a compression ratio of
9.0:1. An optional overhead camshaft engine equipped
with a four-barrel carburetor has a compression
ratio of 10.5:1 with the same bore and stroke.
Six optional V-8 engines are available on special
order, two having 350 cubic inch displacement with
3 7/8" bore and 3 3/4" stroke. The compression
rations are 9.2:1 and 10.5:1.
Four 400 cubic inch
displacement engines available in the G.T.O. have a
4.120" bore and 3 3/4" stroke. These engines have
compression ratios of 8.6:1 and 10.75:1. One of these
engines is for use in Ram-Air cars only and incor
porates a camshaft and valve train specifically for
the Ram-Air engine.
Twenty-five different engine transmission combi
nations are available. These combinations and their
usages are shown on the engine chart (Figs. 6-2 and
6-3).
Engine identification is facilitated by a letter code
stamped below the production engine serial number
on V-8 engines (Fig. 6-5). The code is stamped on
the block in front of the right bank of cylinders. The
engine code for 6-cylinder engines is stamped on the
cylinder head contact surface of the block behind the
oil filler pipe (Fig. 6-4)* By referring to the identi
fication code and the engine chart, each engine may
be readily identified.
The vehicle identification number is stamped on
the right rear lower side of the six-cylinder engine
block and to the right of the timing chain cover on
V-8 engines (Fig. 6-6).
PONTIAC ENGINES
Pontiac V-8 engine is used in all models.
Dis
placement is 400 cubic inches provided by 4.120"
bore and 3 3/4" stroke in all models.
A 428 and 428
High Output are available on special order. Dis
placement in these special order engines is 428 cubic
inches provided by 4.120" bore and 4" stroke.
Three compression ratios are available: 8.6:1 on
regular fuel engines, 10
o
5:l on premium engines, and
10.75:1 on 428 high output.
Eleven different engine-transmission combinations
are
available; these combinations and the major
components of each are shown in Fig. 6-1.
Engine identification is facilitated by a letter code
stamped below the production engine number. By
referring to Fig. 6-1 and using the identification
letters, major engine components can be determined.
The engine features completely machined combus
tion chambers, overhead valves, ball pivot rocker
arm construction, harmonic balancer, hydraulic lift
ers, aluminum pistons, straight valve guides, supe
rior crankcase ventilation and lubrication systems,
and large displacement combined with high compres
sion ratio for utmost performance and economy.