70-81 ENGINES CODES

 

  Identify a PONTIAC engine block is very simple, the code is entered, or rather "hit" on the front right of the cylinder block (when you're driving), close to the plane of the cylinder head gasket. Often it isn't visible at first sight either because it may be hidden by rust, paint or air conditioning compressor support. You will find a set of a pair of letters designating the engine code and number that is the serial number of the engine.

  Below you will find the 180 codes for engines installed in firebird. Generally we can see that PONTIAC for blocks codes beginning with "W" for engines with manual transmission and codes beginning with "Y" for engines with automatic transmission, this for the V8 engine.

The color codes in the table below are made to differentiate the four brands of engine fitted to the firebird.

PONTIAC CHEVROLET BUICK OLDSMOBILE

 

  1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981
A3         400              
AA         350              
AD         400              
AH         400              
AT         400              
AU         455             265
AW                       265
AZ                       265
BA                       265
BD                       301
BJ                       301
BO                       301
CAA   250                    
CAB   250                    
CBA     250                  
CBG     250                  
CBJ     250                  
CC             250          
CCA       250                
CCB       250                
CCC       250                
CCD       250                
CD             250          
CEL                     305  
CEM                     305  
CF             250          
CH             250          
CJ             250         301
CL             250          
CSD     250                  
D6A                       305
D6B                       305
D6C                       305
D6D                       305
DB                       265
DC                       265
DH                       265
DHA                       305
DHB                       305
DHC                       305
DHD                       305
DHF                       305
DHH                       305
DHJ                       305
DHK                       305
DHU                       305
DHZ                       305
DJ                       305
DKB                       305
DND                       305
DNF                   305    
DNJ                   305    
DNK                   305    
DNZ                   305    
DRY                   350    
EA                 231      
EC                 231      
EE                 231      
HF                 350      
HJ                 350      
HL                 350      
HR                 350      
JL           250            
JT           250            
JU           250            
LZ                       231
MS                     231  
MX                     231  
NA                       231
NB                       231
NC                       231
ND                       231
NF                       231
NJ                       231
NK                       231
NL                   231   231
NZ                       231
OJ                     231  
OK                     231  
OL                     231  
OM                     231  
ON                     231  
OZ                     231  
Q6                   403    
Q8               350        
Q9               350        
QE                   403    
QJ                   403    
QK                   403    
QL                   403    
RA                       231
RB                       231
RC                       231
RD                       231
RK                       231
RL                       231
RX                   231    
RY                   231    
SG               231        
SI               231        
SK               231        
SM               231        
ST               231        
SU               231        
TD                   403    
TE                   403    
TH                 305      
TJ                 305      
TK                 305      
TX               350        
TY               350        
U2               403 403      
U3               403 403      
VA               403 403      
VB               403 403      
W8       455 455              
WA         350     400        
WB               301        
WC   455             400      
WD     455                  
WH 400                 400    
WJ   455                    
WK   400 400 400                
WL   455                    
WM     455                  
WN   350       350            
WP   350   400                
WR   350 350                  
WS 400 400   400                
WT 400 400   455 400 400 400          
WU 350 350         400          
WW 400     455                
WX           455 455          
X4                   301    
X6                   301    
X7                 400      
XA               400        
XC                     301  
XM                     301  
XN 400     400             301  
XP 400                 301    
XR   350   350           301 265  
XX 400 400                    
Y3       400 400              
Y6       400       400        
Y8       455 455              
Y9             400 350        
YA       455 350       400      
YB     455     350 350          
YC   455   455                
YD       455                
YE   455 455                  
YF         400              
YG       400       400        
YH         400     301        
YK       455       301        
YL       350 400           301  
YM         400              
YN   350       350         301  
YO           350            
YP   350                    
YR     350 350     350          
YS 400 400 400 400   400 400          
YT       400 400              
YU 350 350 350           400      
YW         455              
YX   400 400 400                
YY         455              
YZ 400     400 400   400          
ZA         350              
ZB 250                      
ZF             350          
ZG 250                      
ZJ         400              
ZK       400 400   400          
ZP           350            
ZR       350                
ZS     400   400              
ZT         400              
ZX     400 400     350          
  1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981

 

  There is another code that is located along the lid and timing cover. It should be the end of the VIN code of the car (the panel). If it doesn't match, engine is not from the factory.

The 350-400-455ci PONTIAC

  In 1970, all blocks received three additional holes (5 in total per side) for the installation of engines in the new pontiac firebird chassis of the second generation. Below the serial numbers had to be sure to identify the engine size. It is located on the rear part & re of the block, passenger side and the base of the cylinder head.

1970 (350 ci) #9799916
1970 (400 ci) #9799914
1970 (400 RA III) #9799914
1970 (400 RA IV) #979991(5)
1970 (400 RA V) #481708
1970 (455 ci) #9799140
1971 (350 ci) #481990
1971 (400 ci) #481988
1971 (455 HO) #483677
1971 (455 HO) #485428 late
1972 (350 ci) #481990
1972 (366 ci) #(485)212
1972 (400 ci) #481988
1972 (455 ci) #485428

1973 (350 ci) #488986
1973 (400 ci) #481988
1973 (455 ci) #485428
1973 (455 SD) #(490)132
1974 (350 ci) #488986
1974 (400 ci) #481988
1974 (455 ci) #485428
1974 (455 SD) #(490)132
1975 (350 ci) #488986
1975 (400 ci) #488986 early
1975 (400 ci) #500557 late
1975 (455 ci) #500813
1976 (350 ci) #488986
1976 (400 ci) #500557
1976 (455 ci) #500813
1977 (400 ci) #568557
1978 (400 ci) #568557
1979 (400 ci) #568557

 

  All blocks have a date code of manufacture at the foot of the distributor. It consists of a letter (A = January, B = February ... L = December) and two or three-digit day of the month, the last being the year. Example: D036 -> April 3, 1976. This is to match the casting number in the table above not to be confused with the 60s.

 


  Unlike this time and our European cars, a Pontiac wasn't necessarily motorized by PONTIAC engine, and all displacements combined, there was also Chevrolet, Buick and Oldsmobile engines on the second generation firebird. This bio-diversity appeared in 1977.

  Chevrolet V8 engine offered were only the small block 305ci (5.0L) and 350ci (5.7L), but also had to rely on the venerable six-cylinder fitted to the firebird base for almost forever. So apart from the L6, the two V8 were installed from 1977 to 1981. The 305 is 3.736"x3.48" (95x88.4 mm) bore and stroke and from 125 to 150hp depending on the year. The 350 is 4.00"x3.48" (102x88mm).

  For Buick, only the V6 231ci (3.8L) versions of this base was offer. Bore 3.8"x3.85" (96.5x97.8mm). In fact we must consider this V6 as a V8 350 which it would have been cut 2 cylinders. Used from 1978 to 1981, producing from 105 to 115hp.

  Oldsmobile V8 350ci (for 1977) and the famous 403ci (1977 to 1979) eventually to expand the range of the engine. The 350ci's cylinder heads were manufactured by the PMD (Pontiac Motor Division) but only from 1977 to 1980. The 403 is a special block with a bore/stroke of 4.351"x3,385" (110.5x86mm) as saying that the short stroke favors high speeds engine. But with a big bore, the wall cylinders are thin and the coolant doesn't pass between the cylinders, causing some overheating problems ... Power 185 hp (138 kW) and 320 lb-ft (433 Nm).

 

CYLINDER HEAD

 

  They are as important as the engine code because often they are replaced by "good" versions, those that offer more compression and more power. 3 codes on them, for example: Type: 4X, 5C, 6X, date and combustion chamber size....

Here is a picture of one of my head to illustrate the locations of these codes and serve as an example.

    

1973-74, 4X heads

4X-1H, 455, 2.11/1.66" valve, press in stud, 114cc
4X-3H, 400 4bbl, 2.11/1.66" valve, screw in stud, 98cc
4X-4H, 400 2bbl, 1.96/1.66 "valve, press in stud
4X-7H, 400 4bbl, 2.11/1.66" valve, screw in stud, 98cc
46, 350 2bbl/4bbl, 1.96/1.66" valve, press in stud, 86cc
4C-5, 350 wAIR, 1.96/1.66" valve, press in stud, 86cc
4C-9, 400 wAIR, 1.96/1.66" valve, press in stud, 98cc

 

1975, 5C, valve length 4.960/4.949", diameter 2.11/1.66" and 30°/45° valve seat

5C-4, 350 4bbl, 93cc
5C-7, 350 4bbl AIR, 93cc
5C-8, 400 4bbl, 101cc
5C-9, 400 4bbl AIR, 101cc

 

The 6X heads were installed after February 1975. The 6X-4 and 6X-8 heads were used only after 1976. diameter 2.11/1.66"

6X-4, 350 (et 77-79 T/A 6.6), 93cc
6X-8, 400, 101cc
6H-6, 455, 124cc
6S-7, 350 w/AIR, 93cc
6S-9, 400 w/AIR, 101cc

 

  The date of manufacture; HO84 here and based on the first letter designating the month (A = January, B = February, etc. ...), and the third two digits for the day (01 is the first of the month up to 31) and finally the last digit for the year (4 = 1974 5 = 1975, etc. ...). This gives H = August 08 = Day 8, 4 = 1974. So my heads were made August 8, 1974 which is normal for a car model produced in 1975 late 1974.

Combustion chamber size: 4 corresponding to the small size which is 93cc for the 5C heads.

YEAR Ci POWER HEAD CODE VALVE COMP.
1970 350 255HP 11 1.96/1.66 8.8 c.r.
400 265HP 11 1.96/1.66 8.6 c.r.
400 290HP 16 (small valves) 1.96/1.66 10 c.r.
400 330HP Big Car 16 1.96/1.66 10 c.r.
400 330HP 12 (manual) 2.11/1.77 72cc
400 330HP 13 (automatic) 2.11/1.77 72cc
400 345HP(FB/RAIII) 12 2.11/1.77 72cc
400 350HP(GP) 13 2.11/1.77 72cc
400 350HP(GTO) 12 (manual) 2.11/1.77 72cc
400 350HP(GTO) 13 (automatic) 2.11/1.77 72cc
400 366HP(GTO) 12 (RA III) 2.11/1.77 72cc
400 370HP(RA IV) 614 (round port) 2.11/1.77 71cc
455 360HP Big Car 15 1.96/1.66 87cc
455 360/370HP(GTO/GP) 64 2.11/1.77 87cc
1971 350 250HP 94 1.96/1.66 96cc
400 265HP 99 1.96/1.66 98cc
400 300HP 96 2.11/1.77 96cc
455 280HP 98 1.96/1.66 114cc
455 325HP 66 2.11/1.77 114cc
455 335HP (455HO) 197 (191) round port 2.11/1.77 111cc
1972 350 175HP 7h1 1.96/1.77 7.6cr
400 200HP 7j2 1.96/1.77 8.4cr
400 250HP 7k3 2.11/1.77 96cc
455 200HP 7L4 2.11/1.77 114cc
455 250HP 7M4 2.11/1.77 114cc
455 250HP 7M5 2.11/1.77 114cc
455 300HP(455HO) 7F6 round port 2.11/1.77 111cc
1973 350 150/175HP 46/4c 1.96/1.66 96cc
400 170/185HP 46/4c 1.96/1.66 98cc
400 200HP 4x/4c 2.11/1.66 98cc
400 230HP 4x/screw in stud 2.11/1.66 98cc
455 215/250HP 4x/screw in stud 2.11/1.66 114cc
455 290HP(455SD) 16/X (round port) 2.11/1.77 111cc
1974 350 155/170HP 46/4c 1.96/1.66 7.6cr
350 200HP(GTO) 46 (screw in stud) 1.96/1.66 7.6cr
400 175/190HP 46/4c 1.96/1.66 8.1cr
400 200HP 4x/4c 1.96/1.66 98cc
400 225HP(AT) 4x (screw in stud) 2.11/1.66 98cc
400 225HP(AT) 4c 2.11/1.66 98cc
400 225HP(MT) 4x (screw in stud) 2.11/1.66 98cc
455 215/250 4x (screw in stud) 2.11/1.66 114cc
455 215/250 4c 2.11/1.66 114cc
455 290HP(455SD) 16/X (round port) 2.11/1.77 111cc
1975 350 ALL 5c 2.11/1.66 7.6cr
400 ALL 5c/6s 2.11/1.66 7.6cr
455 AIR 6s 2.11/1.66 7.6cr
350 HO/non-air 6h 2.11/1.66 7.6cr
1976 350 ALL 6X/6S 2.11/1.66 7.6cr
400 ALL 6X/6S 2.11/1.66 7.6cr
455 AIR 6S 2.11/1.66 7.6cr
455 HO/non-air 6H 2.11/1.66 7.6cr
1977 301 ALL 01 1.72/1.50 8.2cr
350 ALL 6X/6S 2.11/1.66 7.6cr
400 180HP 6X 2.11/1.66 7.6cr
400 200HP 6X 2.11/1.66 8.0cr
1978 301 ALL 01/02 1.72/1.50 8.2cr
350 ALL 6X/6S 2.11/1.66 7.6cr
400 180HP 6X 2.11/1.66 7.6cr
400 220HP 6X 2.11/1.66 8.1cr
1979 301 ALL 01 1.72/1.50 8.2cr
400 ALL 6X 2.11/1.66 8.1cr