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Small Block Head ID

  
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Small Block Head ID

 
tuffnuff tuffnuff
Moderator | Posts: 7828 | Joined: 12/09
Posted: 01/29/13
10:21 AM

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
Also Borrowed from CAR CRAFT Magazine
No’s 1-6 are small-chamber, hi-comp and must have dished pistons to get comp below 10.5:1. No’s 1-7 have nonhardened exhaust valve seats which must be replaced for use with unleaded fuel.
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

Smile  
When The Flag Drops.,.

tuffnuff

The Bull ***t Stops.,.
tuffnuff

P. Engineer, Engine Builder

pepsi1 pepsi1
Guru | Posts: 1718 | Joined: 09/11
Posted: 01/29/13
11:37 AM

+1 Tuff Nice post.

Bob  

skyeking skyeking
Addict | Posts: 2738 | Joined: 08/09
Posted: 01/29/13
04:14 PM

Hi there to the college of Knowledge.
 Hi Guys...  
skyeking

tuffnuff tuffnuff
Moderator | Posts: 7828 | Joined: 12/09
Posted: 01/29/13
04:39 PM

Hi Skye, how's everything going.

Smile  
When The Flag Drops.,.

tuffnuff

The Bull ***t Stops.,.
tuffnuff

P. Engineer, Engine Builder