SBC cylinder head identification
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;Casting number | ;Casting number | ||
:Usually 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. | :Usually 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. | :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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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 guide plates are in place can further ID them. Be aware that screw-in studs/guide plates 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. | 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 guide plates are in place can further ID them. Be aware that screw-in studs/guide plates 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. | ||
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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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|[[File:Induction hardened seat vortec.jpg|thumb|center|400px|Induction hardened Vortec exhaust seat, note the discoloed area around seat]] | |[[File:Induction hardened seat vortec.jpg|thumb|center|400px|Induction hardened Vortec exhaust seat, note the discoloed 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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*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's 261, 624. Also 1987-'95 center bolt valve cover-type head c/n 14102191 can also have the 3/8" exhaust valve stem. | *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's 261, 624. Also 1987-'95 center bolt valve cover-type head c/n 14102191 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 RPM most performance camshafts need to make peak power. Some casting numbers for them are 187, 191, 193. Similar to the swirl port heads, but without the swirl-inducing vane are c/n's 14011083 and 14096217. | + | *Usually swirl port TBI SBC heads are not used in high performance applications because they run out of breath earlier than the RPM most performance camshafts need to make peak power. 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's 14011083 and 14096217. |
==Resources== | ==Resources== | ||
;SBC casting numbers | ;SBC casting numbers | ||
| − | *[http://outintheshop.com/faq/casting/castings2.html SBC head casting number "go-to" site] | + | *[http://outintheshop.com/faq/casting/castings2.html SBC head casting number "go-to" site] from outintheshop.com |
*[http://web.archive.org/web/20080518030656/http://www.mortec.com/ MorTec, archived] | *[http://web.archive.org/web/20080518030656/http://www.mortec.com/ MorTec, archived] | ||
| − | *[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'''.]] | ||
;General | ;General | ||
| − | *[http://www.nastyz28.com/sbchevy/sblock.php SBC general decoding information] | + | *[http://www.nastyz28.com/sbchevy/sblock.php SBC general decoding information] from nastyz28.com |
*[[Chevy engine casting numbers]] Crankshaft Coalition wiki article | *[[Chevy engine casting numbers]] Crankshaft Coalition wiki article | ||
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