Cylinder Head Casting Numbers
These head castings were used in various other models of the Chevrolet lineup such as the passenger car, Chevy II/Nova, Camaro and Corvette. Only Chevelle-specific information is listed here to conserve space. Some casting numbers are NOT listed as they may have been used in other models of the Chevrolet lineup but were NOT used in the Chevelle - such as the 1965 409cid heads #3830817 & #3852583 or 67 Camaro heads #3876775.
The casting number is probably the most significant feature on a cylinder head as it is the hardest to alter. The casting date is usually found near the casting number. Both are found under the valve cover be it a small block V8 (283/307/327/350) or big block Mark IV V8 (396/402/454).
It is important to remember the 'to' and 'from' dates listed may vary due to production lead time and stock inventories being depleted. For example just because a particular head casting may be listed as being used from January to April doesn't imply that the engine assembly plants discarded all pre-January heads or on the 1st of May discard all heads they had in inventory to begin using the newer design.
Casting clocks. Note the 11 dots plus the number 0 indicating the particular
hour of a shift the heads were cast.
Cylinder heads are normally date coded in the form of a letter for the month (see table below), two numbers for the day and a single number for the year. For example, C259 indicates a date of March 25, 1969.
| V8 Cylinder Head Casting Month Codes | |||
| A - January | B - February | C - March | D - April |
| E - May | F - June | G - July | H - August |
| I - September | J - October | K - November | L - December |
Caveats to production dates. Due to inventories, shipping schedules, etc. it is entirely possible that cylinder heads being phased out of production may still appear on Chevelles built after that time.
| Head Number |
Year | Engine | Horsepower | Valve
Size Int./Exh. |
Combustion Chamber cc. |
Notes |
| 3795896 | 1964 | 283 327 |
195,
220 250 |
1.72/1.50 | 59.669 | Used in 1964 and 1965. |
| 3782461 | 1964 1965 1966 |
327 327 327 |
300 250, 300 275 |
1.94/1.50 | 62.076 | Production ended approximately
June of 1966 and replaced with #3890462. Casting symbol on exterior
face of head is the infamous double-hump design. |
| 1964 1965 1966 |
327 327 327 |
350 350 350 |
2.02/1.60 | 62.076 | 1966 is late March introduction. | |
| 3795896 | 1965 | 283 | 195, 220 | 1.72/1.50 | 59.669 | Casting symbol on exterior
face of head is single centered pyramid on square block. |
| 3856208 | 1965 | 396 | 375 | 2.19/1.75 | 108.989 | First square-port Mark IV head. Has spark plug shield boss. |
| 3872702 | 1966 | 396 | 325, 360 | 2.06/1.72 | 98.427 | All oval-port applications. Has spark plug shield boss. It is debatable as to whether these plug shields were used on the Chevelle but the shields listed in Chevrolet parts books included the Chevelle application. |
| 3873858 | 1966 | 396 | 375 | 2.19/1.72 | 108.989 | All high performance square-port engine applications. Has spark plug shield boss. |
| 3884520 | 1966 1967 |
283 283 |
195,
220 195 |
1.72/1.50 | 60.530 | |
| 3890462 | 1966 1967 1966 ** 1967 |
327 327 327 327 |
275 275 350 325 |
1.94/1.50 1.94/1.50 2.02/1.60 2.02/1.60 |
62.076 63.305 62.076 63.305 |
Similar to 3782461. Used
from January 1966 through May 1967.
|
| 3904390 | 1967 | 396 | 325, 350 | 2.06/1.72 | 98.427 | First head without spark plug shield boss. Used until January when replaced with #3909802. |
| 3904391 | 1967 | 396 | 375 | 2.19/1.72 | 106.8 | Used at least through May
1967 when replaced with #3919840. |
| 3909802 | 1967 | 396 | 325, 350 | 2.06/1.72 | 100.967 | January through April of 1967, with redesigned combustion chamber. June 1967 casting dates have been reported for this head. |
| 3911032 | 1968 | 307 | 200 | 1.72/1.50 | 69.629 | Used in 1968 only. Has temperature
sending unit boss. |
| 3917215 | 1967 1968 |
396 | 325, 350 | 2.06/1.72 | 100.967 | First Mark IV oval-port with temperature sending unit boss, otherwise identical to #3909802. Production from May 1967 to May 1968. |
| 3917291 | 1967 1968 |
327 | 275 | 1.94/1.50 | 63.305 | Used in late 1967 (May/April)
and all 1968. Identical to #3890462 except it has the temperature
sending boss. The late 1967 unit has the temperature sending
unit boss but is not tapped. |
| 3917291 | 1967 1968 |
327 | 325 | 2.02/1.60 | 63.995 | Combustion chamber enlarged
and valve guide boss diameter increased to accept the 2.02/1.60
valves. |
| 3917293 | 1968 | 327 | 250 | 1.72/1.50 | 75.340 | Low compression, identical
to #3884520 except for combustion chamber change and addition
of temperature sending boss. |
| 3919840 | 1967 1968 1969 |
396 | 375 | 2.19/1.72 | 106.8 | First Mark IV to have temperature
sending boss. The late 1967 unit has the temperature sending
unit boss but is not tapped. Identical to #3904391 except for
temperature sending unit boss and two accessory bolt holes added. |
| 3919842 | 1969 | 396 | 375 (L89) | 2.19/1.84 | 106.8 | Aluminum head with temperature sending unit boss, two accessory holes drilled and tapped, revised exhaust manifold surface. Two versions were used during 1968 (non-Chevelle) and 1969. The 1968 and early 1969 version had plugs in both ends of the cylinder head. Approximately June of 1969 one plug was eliminated. |
| 3927185 | 1969 1970 |
307 | 200 | 1.72/1.50 | 69.625 | Identical to #3884520 except
has temperature sending unit boss. Three accessory bolt holes
added to each end of the head and combustion chamber revised.
 |
| 3927186 | 1969 1970 |
350 | 300 | 1.94/1.50 | 63.305 | Similar to #3917291 &
#3782461, but with temperature sending unit boss, three accessory
holes and casting symbol was smaller. |
| 3931063 | 1969 | 396 | 325, 350 | 2.06/1.72 | 100.967 | Similar to #3909802 & 3917215 with two accessory bosses above #3 (or #6) exhaust ports for air conditioning rear support bracket. Straight casting flashing. |
| 3932441 | 1969 1970 |
350 | 250,
255 250 |
1.94/1.50 | 76.26 | Similar to #3927186 with
redesigned combustion chamber. |
| 3947041 | 1969 1970 |
350 | 300 | 1.94/1.50 | 63.305 | Similar to #3782461 with
redesigned combustion chamber, addition of a temperature sending
unit boss and three accessory holes on end. |
| 3964290 | 1969 1970 1970 |
396 402 454 |
325,
350 330, 350 360 |
2.06/1.72 | 100.967 | Similar to #3931063 with spark plug seat changed to tapered, "peanut" plug but early castings had standard, "N" reach plug. Straight casting flashing. |
| 3964291 | 1969 1970 |
396 427 402 454 |
375 425 375 450 |
2.19/1.88 | 109.037 | Similar to #3919840 with
spark plug seat changed to tapered, "peanut" plug
but early castings had standard, "N" reach plug. Last
closed chamber cast iron square-port head. Produced in both
plug designs for service replacement of 1965 through 1969 applications. |
| 3973487 | 1971 1972 |
350 350 |
245,
270 165, 175 |
1.94/1.50 | 75.47 | Similar to #3832441 &
#3782461 with redesigned combustion chamber, addition of temperature
sending unit boss, three accessory bolt holes added to end of
head, tapered spark plug seat and different external identification
symbol cast near the internal casting number. |
| 3973487X | 1972 | 350 | 165, 175 | 1.94/1.50 | 75.47 | Used only in late 1972 and
overlapped production with #3998993. |
| 3986339 | 1971 | 307 | 200 | 1.72/1.50 | 74.56 | Similar to #3884520 with
redesigned combustion chamber, temperature sending unit boss
and tapered spark plug seat. |
| 3993820 | 1971 | 402 454 |
300 365 |
2.06/1.75 | 113.060 | Cast iron, oval-port and similar to #3931063 with change to open-chamber design, redesigned intake and exhaust valve seats, and tapered spark plugs. |
| 3994026 | 1971 | 454 | 425 | 2.19/1.88 | 118.000 | Cast iron, square-port with tapered spark plug. Last Mark IV square-port with open chamber design. |
| 3998991 | 1972 | 307 | 130 | 1.72/1.50 | 74.56 | Similar to #3795896 with
tapered spark plug, redesigned combustion chamber, and temperature
sending unit boss. First head to use hardened valve seats for
unleaded fuel. |
| 3998993 | 1972 1973 1973 |
350 307 350 |
165,
175 115 145, 175 |
1.94/1.50 | 75.47 | Introduced mid-year (January)
to replace #3973487X. |
| 3999241 | 1972 | 402 454 |
240 270 |
2.06/1.72 | 113.06 | Similar to #3993820 with tapered spark plug seat. |
| 353049 | 1973 | 454 | 245* | 2.06/1.72 | 113.06 | Used for all 1973 454 applications. |
| 333882 | 1974-75 1974 1975 |
350 400 400 |
All 150, 180 175 |
1.94/1.50 | 75.47 | Similar to #3998993 with tapered spark plug seat. |
| 336781 | 1974 1975 |
454 454 |
235 215 |
2.06/1.72 | 113.06 | Used for all 1974 and early 1975. Replace by #346236 mid-year 1975. |
| 346236 | 1975 | 454 | 215 | 2.06/1.72 | 113.06 | Replaced #336781 mid-year 1975. |
* The 1973 454 Corvette engine was rated at 270hp. Since this head has the same intake/exhaust and cc volume, it is not known why it is listed at 245hp for 1973.
** The L79 327/350 engine was never available in the Chevelle lineup in 1966; this cylinder head was used on the 1966 L79/350 in the Chevy II/Nova and Corvette.
1966 Oval port head; notice tapped bosses for spark plug shields.
The top head is the 'lower horsepower' version (300hp and under) used on 67-68 327 applications with 1.94 intake and 1.50 exhaust while the bottom head is the performance version (325hp and higher) used on 67-68 327 applications with 2.02 intake and 1.74 exhaust. These happen to be casting #3917291 with 63.305 and 63.995 cc combustion chambers respectively. Other 'pairs' of 327 heads 1.94 vs. 2.02 intake valve size and different combustion chamber sizes are found in other years with casting numbers 3782461 (64-66 model years) and 3890462 (66-67 model years).
