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Old 11-08-2009, 07:44 PM
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Z28SSMAN Z28SSMAN is offline
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Default Not all double hump sbc heads the same?

Back in the late 60s, we always thought if you had the "double hump" heads, you had the best available. Sounds like there were a few versions...

Chevy Small Block Cylinder Head Identification Guide Key Cast Marks Cast Nos. Description
A Rectangle 460 ‘55 & up 265/283 low comp (8:1) 1.72/1.50 valves
B Narrow triangle over rectangle 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” 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
H Small “camel humps” 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
Top Ten Production CSB Cylinder Heads
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Old 11-12-2009, 10:48 AM
MR.hp MR.hp is offline
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GM heads are so lame and they all go slow as piss
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