|
Key
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Cast Marks
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Cast Nos.
|
Description
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|
A
|
Rectangle
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460
|
‘55 & up 265/283 low comp (8:1) 1.72/1.50 valves
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|
B
|
Narrow triangle over rectangle
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520, 896
|
‘58 & up 283 PowerPak/’57-’60 Fuel Inj.,9.25:1 CR, 1.72/1.50 valves, 59cc chamber; could be good replacement on late 305 but no accessory bosses.
|
|
C
|
Vertical bar over rectangle
|
997
|
‘57 Corvette 270HP, 9.5:1 CR, chamber similar to PowerPak but with sharp corners in plug shroud area
|
|
D
|
2 vert bars over rect
|
997
|
‘56 Corvette 2X4 bbl, 283; ‘58 pass car FI; chamber same as ‘57 270HP Corvette
|
|
E, F
|
Large “camel humps”
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291, 461, 461X, 462
|
Original hi-perf or “fuelie” heads; chamber sizes are 62-64cc; both 1.94/1.50 & 2.02/1.60 valve versions available; 291 on 327’s thr ‘68; 291 have temp sender hole; 462 don't
|
|
G
|
Left-facing right triangle
|
041
|
‘69-’70 350/300HP, accessory bolt holes, most have 1.94/1.50 valves
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|
H
|
Small “camel humps”
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186, 492
|
Later hi-perf or “fuelie” heads, some 186 (‘69 & later) & all 492 have accessory bolt holes; 1.94/1.50 or 2.02/1.60 valves; 64cc chambers; ‘70 LT1/Z28 use 492; avail as PN3987376
|
|
I
|
Large triangle over rectangle (“crown”)
|
882
|
Large chamber (76cc), hardened exhaust valve seats, compromised intake port(‘71-’76 350/400cid), best of lightweight heads
|
|
J
|
NONE
|
113
|
‘86-’90 Corvette/ present 350-HO aluminum, no exhaust heat, 58cc chamber, 1.94/1.50 valves, centerbolt valve covers; good street head, ‘88-on have raised D ex port, 3/8 screw-in studs
|
|
K
|
3 right-facing “stairs” (“bench” on intake runner)
|
487
|
‘71-’76 76cc, best large-chamber head; 1.94/1.50 & 2.02/1.60 valves available; latter machined for screw-in studs & guideplates
|
|
L
|
Right-facing “bench”
|
993
|
Common big-chamber head, not a lightweight casting; sim to 487; may have steam holes
|
|
M
|
One triangle
|
882
|
Alternative marking for 882; see I, above
|
|
N
|
2 triangles
|
624
|
Late-model lightweight casting version of 882
|
|
O
|
“Saddle” and vertical bar
|
416
|
Late-model 305, conventional valve covers, intake port not restricted; lightweight; 57cc chamb
|
|
P
|
Double (Captain’s) bars
|
193
|
Mid-’80’s style centerbolt cover with restrictive vane cast in intake port (hi-swirl); not recommended for high-performance applications
|
|
Rank
|
Cast #
|
Good Points
|
Bad Points
|
|
1
|
3782461X
|
Hi comp (57.5cc), best ports of any OEM production cast-iron head, intake runner vol 170-180cc
|
No accessory bolt holes, rare, likely to be cracked, 2.02/1.60 versions very rare
|
|
2
|
3991492
|
‘70 hi-comp (61.2cc), good ports, acc bolt holes, 2.02/1.60 valve versions have screw-in studs & gplates
|
Close proximity of water jacket to spring pocket on 492s cast prior to 1972 req special seat cutter if using larger springs
|
|
3
|
3890462
|
Ports similar to 461, but better comb chamber shape
|
More common than 461-461X, but still rare; no acc bolt holes
|
|
4
|
3782461
|
Similar to 461X but with smaller intake ports
|
Rare, probably cracked, no acc bolt holes
|
|
5
|
3927186
|
‘64-’70, av chamb vol 64cc, ‘69-’70 have acc bolt holes
|
Rare, valvespring seats close to water jackets
|
|
6
|
3947041
|
‘69 350/300 HP, good chamb (similar to 462), acc bolt holes
|
Very rare, valvespring seats close to water jacket
|
|
7
|
3932441
|
‘69-’70, large chambers (73cc), some have steam holes for 400 blocks, ports decent, accessory bolt holes
|
No 2.02/1.60 valve versions from factory
|
|
8
|
3973487
|
‘71, 76cc, like 441 but better chamb, hard seats, acc bolt holes
|
Big chamb needs domed pistons to get hi-comp
|
|
9
|
3998993
|
‘71-’76 US/ ‘85-’88 Mexico, similar to 487, widely available
|
Big chamb needs domed pistons to get hi-comp
|
|
10
|
332882
|
‘71-’76, 350/400, big chamb, acc bolt holes, hard seats
|
Changed intake ports, become worse, BEST of the worst
|
|
11
|
462624
|
‘76-’78, 305, 58cc chamb, 1.84/1.50 valves, hardened seats, accessory bolt holes, best of the 305 heads
|
1.84/1.50 valves and ports too small for large cid; accepts 1.94/1.60 valves & seats
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