SBC cylinder head identification
From Crankshaft Coalition Wiki
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| − | =Overview= | + | |
| + | ==Overview== | ||
Most cylinder heads are identified in a general sense from simply looking at them. But just knowing the generic type of engine does not begin to tell the whole story. There are a wide variety of heads for most any given engine type and in many cases there's a lot of difference between them in their potential for performance. | Most cylinder heads are identified in a general sense from simply looking at them. But just knowing the generic type of engine does not begin to tell the whole story. There are a wide variety of heads for most any given engine type and in many cases there's a lot of difference between them in their potential for performance. | ||
| − | =Basics of cylinder head identification= | + | ==Basics of cylinder head identification== |
| + | A big block Chevy (BBC) or small block Chevy (SBC) head is readily recognized by most, as are MOPAR Hemi heads, small block Ford (SBF) heads, and depending on experience and engine preferences, others as well. | ||
| − | + | Telling the difference between the various SBC heads can be hard if all there is to go on is what they look like. While there are visual cues that can help tell them apart (like the fuelie 'double hump'), there are several ways to ID cylinder heads closer than using just visual cues. | |
| − | + | ===Casting number=== | |
| − | + | The casting number (c/n) is cast into the head as opposed to being stamped. The casting number is usually the best thing to use to tell what a cylinder head was originally used on and its potential for performance use. | |
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| − | + | When referring to the different casting numbers of Chevy heads, typically the last three digits are used because in most cases these numbers are not reused. There is always an exception to the rule; in this case it's c/n 462- which was used on no less than SIX different castings! | |
| − | + | The casting number may be out in the open where it can be easily seen, like the Pontiac V8, or somewhat harder to see but still visible without taking anything off the head, or the number can be under the valve cover or under the head where it's difficult to see without some amount of disassembly. | |
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| − | + | ===Casting date=== | |
| − | + | Like casting numbers, the date code is cast into the head, and may or may not be visible without removing the valve cover. | |
| − | + | The date code generally has a letter followed by two or three numbers. The letter is the month. The next number or two numbers will be the day of the month. The last number is the last digit of the year. | |
| − | + | *Example '''C124''': | |
| + | **C = March (A = Jan., B = Feb., etc.) | ||
| + | **12 = day of the month | ||
| + | **4 = year ending in 4, i.e. 1964, 1974, 1984, etc. | ||
| − | = | + | ===Cast in identifiers=== |
| + | These are different shapes that are usually found on the end of the heads. Some examples are shown [[SBC cylinder head identification#Some common small block Chevy head ID castings|'''below''']]. | ||
==Casting numbers== | ==Casting numbers== | ||
| − | Located under the valve covers, the casting number is the best way to ID a SBC head. The number along with the date code can be used to pinpoint the heads original application fairly closely. Valve sizes (1.94" intake x 1.5" exhaust or 2.02" intake x 1.60" exhaust) and whether or not screw-in studs and | + | Located under the valve covers, the casting number is the best way to ID a SBC head. The number along with the date code can be used to pinpoint the heads original application fairly closely. Valve sizes (1.94" intake x 1.5" exhaust or 2.02" intake x 1.60" exhaust) and whether or not screw-in studs and guideplates are in place can further ID them. Be aware that screw-in studs/guideplates were not used on all, or even most, large valve SBC performance heads from the factory, and if present, they could very well have been added previously. |
| − | Click [[Cylinder head identification#Resources|'''HERE''']] for | + | Click [[Cylinder head identification#Resources|'''HERE''']] for sites with information on casting numbers. |
==Casting identifiers== | ==Casting identifiers== | ||
| − | Through the years, small block Chevy heads have been ID'd by the head's end casting shapes. They don't usually tell the exact details like valve sizes but are useful for telling (at least potentially) a performance head from a non performance head. A casting identifier can differentiate between a large or small combustion chamber volume, also intake port volume, spark plug type (gasketed or tapered seat), whether they were used with a certain type of front accessory arrangement (short or long water pump for instance). | + | Through the years, small block Chevy heads have been ID'd by the head's different end casting shapes. They don't usually tell the exact details like valve sizes but are useful for telling (at least potentially) a performance head from a non performance head. A casting identifier can differentiate between a large or small combustion chamber volume, also intake port volume, spark plug type (gasketed or tapered seat), whether they were used with a certain type of front accessory arrangement (short or long water pump for instance). |
=="Fuelie" heads== | =="Fuelie" heads== | ||
The most recognized end casting identifier of the SBC heads is the "fuelie", "double hump", or "camel hump". It got the name fuelie from the fact that it was used on optional high performance fuel injected SBC engines, mainly installed in the Corvette. The name fuelie is somewhat of a misnomer, however; the fuelie heads were used on carbureted engines as well. | The most recognized end casting identifier of the SBC heads is the "fuelie", "double hump", or "camel hump". It got the name fuelie from the fact that it was used on optional high performance fuel injected SBC engines, mainly installed in the Corvette. The name fuelie is somewhat of a misnomer, however; the fuelie heads were used on carbureted engines as well. | ||
| − | The names "double hump" | + | The names "fuelie", "double hump", or "camel hump" comes from the shape of the casting identifier. These heads were used during the '60s and '70s on various performance engines. |
===Casting number "462" fuelie heads=== | ===Casting number "462" fuelie heads=== | ||
'''462''' is the most-used SBC head casting number out there- at least six different SBC cylinder head casting numbers end in 462, according to 'the books': | '''462''' is the most-used SBC head casting number out there- at least six different SBC cylinder head casting numbers end in 462, according to 'the books': | ||
| − | + | * 3767462 | |
| − | + | * 3782462 | |
| − | + | * 3814462 | |
| − | + | * 3890462 | |
| − | + | * 3891462 | |
| − | + | * 3990462 | |
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===Fuelie casting identifiers=== | ===Fuelie casting identifiers=== | ||
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| − | ===Vortec exhaust seats=== | + | ===L31 Vortec exhaust seats=== |
| − | Early on, there was much made of the supposed difference in flow between the Vortec heads that came with the hardened exhaust seat inserts as opposed to the heads that had induction hardened seats. This was largely due to an oft-repeated, although incorrect statement made by a car magazine that said in essence the | + | Early on, there was much made of the supposed difference in flow between the Vortec heads that came with the hardened exhaust seat inserts as opposed to the heads that had induction hardened seats. This was largely due to an oft-repeated, although incorrect statement made by a car magazine that said in essence the 906 head was to be avoided because of the exhaust seat insert being vastly inferior to the heads with induction hardened exhaust seats. |
The truth has been shown to be that there is virtually no difference in flow between the two, providing the seat is blended into the port. This is a common procedure that's often done in performance builds- regardless of whether the seats are inserts or induction hardened or unhardened. The manufacturing process leaves a lip where the seat and port pocket meet in many instances, and it's this lip that is carefully removed/blended when a head is prepped for performance use, again- regardless of whether there is an insert or not. | The truth has been shown to be that there is virtually no difference in flow between the two, providing the seat is blended into the port. This is a common procedure that's often done in performance builds- regardless of whether the seats are inserts or induction hardened or unhardened. The manufacturing process leaves a lip where the seat and port pocket meet in many instances, and it's this lip that is carefully removed/blended when a head is prepped for performance use, again- regardless of whether there is an insert or not. | ||
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So both the c/n 906 and c/n 062 heads have virtually the exact same performance potential. In fact there are instances like for marine use where the hardened exhaust seat insert is actually preferred over the induction hardened seat. | So both the c/n 906 and c/n 062 heads have virtually the exact same performance potential. In fact there are instances like for marine use where the hardened exhaust seat insert is actually preferred over the induction hardened seat. | ||
{| | {| | ||
| − | |[[File:Induction hardened seat vortec.jpg|thumb|center|400px|Induction hardened Vortec exhaust seat, note the | + | |[[File:Induction hardened seat vortec.jpg|thumb|center|400px|Induction hardened Vortec exhaust seat, note the discolored area around seat]] |
| − | |[[File:Hard insert seat vortec 906.jpg|thumb|center|400px|Hardened | + | |[[File:Hard insert seat vortec 906.jpg|thumb|center|400px|Hardened exhaust seat insert in a c/n 906 Vortec head]] |
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*'''A-''' Rectangle c/n 460, 1955 & up 265/283, 8:1 CR, 1.72" x 1.50" valves. | *'''A-''' Rectangle c/n 460, 1955 & up 265/283, 8:1 CR, 1.72" x 1.50" valves. | ||
| − | *'''B-''' Narrow triangle over rectangle c/n 520, 896, 1958 and up 283 | + | *'''B-''' Narrow triangle over rectangle c/n 520, 896, 1958 and up 283 Power Pak and 1957-'60 FI. 9.25:1 CR, 1.72" x 1.50" valves, 59cc nominal chamber volume. Could be used on a 305 but no accessory holes and has unhardened exhaust seats. |
*'''C-''' Vertical bar over rectangle c/n 997, 1957 Corvette 270 HP, 9.5:1 CR, chamber similar to Power Pak but with sharp corners in plug area. | *'''C-''' Vertical bar over rectangle c/n 997, 1957 Corvette 270 HP, 9.5:1 CR, chamber similar to Power Pak but with sharp corners in plug area. | ||
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*'''G-''' Left-facing right triangle c/n 041, 1969-'70 350/300HP, accessory bolt holes, most have 1.94" x 1.50" valves | *'''G-''' Left-facing right triangle c/n 041, 1969-'70 350/300HP, accessory bolt holes, most have 1.94" x 1.50" valves | ||
| − | *'''H-''' Small “camel hump” c/n 186, 492. Later high performance or “fuelie” heads, some c/n 186 (1969 and later) and all c/n 492 have accessory bolt holes. Either 1.94" x 1.50" or 2.02" x 1.60" valves, 64cc nominal chamber volume. 1970 LT-1/Z-28 use c/n | + | *'''H-''' Small “camel hump” c/n 186, 492. Later high performance or “fuelie” heads, some c/n 186 (1969 and later) and all c/n 492 have accessory bolt holes. Either 1.94" x 1.50" or 2.02" x 1.60" valves, 64cc nominal chamber volume. 1970 LT-1/Z-28 use c/n 186. |
*'''I-''' Large triangle over rectangle (“crown”) c/n 882. Large chamber (76 cc nominal), hardened exhaust valve seats, compromised intake port (1971-'76 350/400 cid). One of the most common smog heads, performance use is limited. | *'''I-''' Large triangle over rectangle (“crown”) c/n 882. Large chamber (76 cc nominal), hardened exhaust valve seats, compromised intake port (1971-'76 350/400 cid). One of the most common smog heads, performance use is limited. | ||
| − | *'''J-''' No casting identifier c/n 113, 1986-'90 Corvette and GMPP 350 HO, aluminum with no exhaust heat cross over, 58cc chamber, 1.94" x 1.50" valves, centerbolt valve covers, good 305 or light performance 350 street head especially if ported, 1988-on have raised D-shaped exhaust port, 3/8" screw-in studs and | + | *'''J-''' No casting identifier c/n 113, 1986-'90 Corvette and GMPP 350 HO, aluminum with no exhaust heat cross over, 58cc chamber, 1.94" x 1.50" valves, centerbolt valve covers, good 305 or light performance 350 street head especially if ported, 1988-on have raised D-shaped exhaust port, 3/8" screw-in studs and guideplates. |
*'''K-''' 3 right-facing “stairs” (“bench” on intake runner) c/n 487. 1971-'76 76 cc, said by many to be the best large chamber head. 1.94" x 1.50" or 2.02" x 1.60" valves were used, big valve heads machined for screw-in studs and guideplates. | *'''K-''' 3 right-facing “stairs” (“bench” on intake runner) c/n 487. 1971-'76 76 cc, said by many to be the best large chamber head. 1.94" x 1.50" or 2.02" x 1.60" valves were used, big valve heads machined for screw-in studs and guideplates. | ||
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*'''P-''' Double (Captain’s) bars c/n 193. Used on TBI equipped engines. Mid 1980-up style centerbolt valve cover. Has restrictive vane cast in intake port to induce swirl/turbulence. Not usually recommended for high RPM performance applications unless serious port work is done. Hardened exhaust seats. | *'''P-''' Double (Captain’s) bars c/n 193. Used on TBI equipped engines. Mid 1980-up style centerbolt valve cover. Has restrictive vane cast in intake port to induce swirl/turbulence. Not usually recommended for high RPM performance applications unless serious port work is done. Hardened exhaust seats. | ||
| + | {{Note1}} Return to [[SBC cylinder head identification#Cast in identifiers|'''Cast in identifiers''']] | ||
==SBC heads to avoid== | ==SBC heads to avoid== | ||
| − | *The c/n 462624 is said to be very prone to cracking. Even though they can be found fitted with 2.02" x 1.60" valves and screw in studs/ | + | *The c/n 462624 is said to be very prone to cracking. Even though they can be found fitted with 2.02" x 1.60" valves and screw in studs/guideplates from the factory, they still are not a good choice for serious performance use. |
| − | *1971-up heads with casting numbers 882, 993, 487, 336 (and others) can have 3/8" exhaust stems as well as 1.72" intake valves. Heavy 20-30 Series truck uses these, mainly. Both small 1.72" intake and 3/8" stem exhaust valves may be found on c/n | + | *1971-up heads with casting numbers 882, 993, 487, 336 (and others) can have 3/8" exhaust stems as well as 1.72" intake valves. Heavy 20-30 Series truck uses these, mainly. Both small 1.72" intake and 3/8" stem exhaust valves may be found on c/n 261, 624. Also 1987-'95 center bolt valve cover-type head c/n 14102191 (76cc chambers and used with some 3/4 - 1 ton truck/van applications) can also have the 3/8" exhaust valve stem. |
| − | *Usually swirl port TBI SBC heads are not used in high performance applications because they run out of breath earlier than the | + | *Usually swirl port TBI SBC heads are not used in high performance applications because most builders do not have a clue on the flow specs. They also do no take into account that these heads produce gobs of low end torque. Although they run out of breath earlier than the Vortec heads, if paired with the proper cam these heads a monsters in the 1/4 mile. Some casting numbers for them are 187, 191, 193. Similar to the [http://www.crankshaftcoalition.com/wiki/Swirl_port_SBC_heads swirl port heads], but without the swirl-inducing vane are c/n 14102187 (5.0L), 14101083 (5.7L TPI) and 14096217 (5.0L). |
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| + | ==Current head casting/part numbers, specs== | ||
| + | [[File:Small block head chart.jpg]] | ||
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| + | ==Calculators== | ||
| + | ;Static compression ratio | ||
| + | *[http://www.wheelspin.net/calc/calc2.html SCR calculator] from wheelspin.com | ||
| + | |||
| + | ;Dynamic compression ratio | ||
| + | *[http://www.empirenet.com/pkelley2/DynamicCR.html Kelly calculator/info] | ||
| + | *[http://www.kb-silvolite.com/calc.php?action=comp2 Keith Black calculator] | ||
==Resources== | ==Resources== | ||
;SBC casting numbers | ;SBC casting numbers | ||
| − | *[http://outintheshop.com/faq/casting/castings2.html SBC head casting number "go-to" site] | + | *[http://www.mortec.com/location.htm Chevy V8 Casting Number Locations] by Mortec |
| − | + | *[http://outintheshop.com/faq/casting/castings2.html SBC head casting number "go-to" site] from outintheshop.com | |
| − | *[http://chevytech.info/3c10o12.html Head info by c/n, some with photos | + | *[http://chevytech.info/3c10o12.html Head info by c/n], some with photos from chevytech |
[[Cylinder head identification#Casting numbers|'''Return to top'''.]] | [[Cylinder head identification#Casting numbers|'''Return to top'''.]] | ||
| + | *[[Chevy engine casting numbers]] Crankshaft Coalition wiki article | ||
| + | ;General | ||
| + | *[http://www.nastyz28.com/sbchevy/sblock.php SBC general decoding information] from nastyz28.com | ||
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[[Category:Identification and decoding]] | [[Category:Identification and decoding]] | ||
[[Category:Engine]] | [[Category:Engine]] | ||
| − | [[Category: | + | [[Category:GM]] |
| + | [[Category:Cylinder head]] | ||
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