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Nissan A-series Engine cylinder heads are of one type: inline valves, pushrod valve system (non-overhead cam), two-valves per cylinder. The head is non-crossflow meaning that exhaust and intake ports are on the same side (left side).
There was one exception: The race-only AY12 cylinder head:
AY12 Cylinder Head
Distinguishing Features
Any A-type cylinder head will bolt onto any A-type engine. However compression and intake ports are big consideration. For best results, match port types (e.g. round-port manifold on round-port head).
Oil passage in the head
An oil passage in the head is needed for some engines
The old 1967-1973 head has the oil passage:
Boss on outside identifies the head
Compare to newer head: no passage:
The newer engine has the passage in the block instead. The solution for Old engine block, Newer head: drill the passage in the head.
Discussion: question about oil blockage
Combustion Chamber
- A,B: Heart-shaped high-compression chamber is good for high-octane gasoline a.k.a closed chamber, peanut-shaped, butterfly-shaped or kidney-shaped
- C: 360 degree open chamber low-compression is good for regular-octane gasoline
- D: Bathtub chamber (from swirl port head)?
Intake Ports
- round. These are best for low-RPM operation
- Small oval (28 mm x 30 mm). The 1974 A13 has this design.
<li>Large oval (28 mm x 34 mm). These are best for high-RPM operation, or for the bigger engines
- Small oval with swirl obstruction. These are good for emissions and fuel economy
Port Sizes
| Ports | Size (mm) | Exhaust | Raised | Note |
| round | 28 | ? * | no | 1971 A12 |
| round | 28 | ? | lowered | 1977 GFU |
| Oval - small | 28x30 | ? * | no | 1973 A13 |
| Oval - large | 28x34 | ? | no | Many A14s |
| Oval - GX | 30x34.5 | 27x29 | Yes | A12Gx (1971-1973) |
Intake Manifolds
All A-series heads will interchange with either type of intake with the following caveats:
- If the intake doesn't have coolant passages, tap the head's coolant ports and install plugs
<li>If the intake does, but the head doesn't, cold-weather starting and
cold-idle may suffer due to insufficient heat. However, warm-engine
operation should be OK.
Valve Springs
The following A-series heads had dual valve springs. There is a small-diameter spring inside the main spring.
- A12GX
- A12T
- A14T
- A14E
- Heads retro-fitted with dual springs
So dual springs are a good indication of a special head, but not conclusive. You will need to check the intake port sizes and other features to make a final determination.
Valve sizes
| Valves | Intake PN (13201) | In. Size | Exhaust PN (13202) | Ex. Size |
| A10, early A12, late A12 Van | 13201-H1000 | 35mm | 13202-H18000 | 29mm |
| A12GX/A12T | 13201-H2300 | 35mm | 13202-H2300 | 29mm |
| Late A12, A13, A12AS | 13201-H2300 | 35mm | 13202-H7400 | ? |
| A13(old),A14 & A15 | 13201-H6200 | 37mm | 13202-H6200, H8900 | 30mm |
| A12A, A14, A15 1982 USA | 13201-H9500 | 35mm | 13202-H9500 | 30mm |
| A12A, A14, A15 1982 canada | 13201-H6200 | 37mm | 13202-H6200 | 30mm |
VALVES (A-SERIES)
4 of each required
- 13201-H2300 35MM/1.38"GX INTAKE VALVE
- 13201-H6200 37MM/1.46" INTAKE VALVE
- 99996-H1100 COMPETITION 37MM/1.46" INTAKE VALVE Polished and tuliped for improved flow characteristics
- 13202-H2300 29MM/1.14" EXHAUST VALVE
- 13202-H6200 30MM/1.18" EXHAUST VALVE
- 99996-H1110 COMPETITION 30MM/ 1.18" EXHAUST VALVE Polished and tuliped for improved flow characteristics.
Reference: 1984 Nissan Competition catalog
Coolant Passages
Coolant passages are below the intake ports (present or not). If present, they can be large holes or small holes
Intake/Exhaust manifold bolt pattern
The 1971-1973 A12 differs from the A13/A14/A15 and most A12s after 1973 except wagons.
Heads By Engine
A10 head
The 1971 A10 head is 9.0:1, same as the A12 head. Does this mean it has a 20% smaller chamber than the A12? Or are the pistons dished differently? It use 29mm and 35mm valves (same as A12).
A12 round-port head
(1971-1973 Datsun 1200)
Intake: 35mm
Exhaust: 29mm
compression ratio 9.0:1 with dished pistons
A ported and polished standard A12 head with larger valves fitted flows about the same as a standard GX head. Also see
The A12 heads and later head provided oil to the rocker armshafts in different locations so you may need to redrill the oil passage.
A12GX Head
The A12GX Engine uses a cylinder head with dual-valve springs for 6800 rpm operation
(compare to stock A12 6400 rpm operation). It used an intake manifold with dual Hitachi HJE38W side-draft carburetors. Compression ration of 10.0 and combustion chamber of 29.1 cm3 with flat-top pistons.
Dual valve springs, GX cylinder head and intake
- 11041-H2302 A12 GX cylinder head (to 6/73)
- 11041-H5703 GX cylinder head (from 7/73) same specs, but for newer engine style
Nissan Competition called the newer head a "GX" head. But this appears to be the A12T head (11041-H5702).
NOTE: Dual valve springs alone is not an indication of the GX head. N10 A14E engines also used dual-springs, but were not large-port heads. Also over the years many heads have had dual springs added. For ID, check the intake port sizes.
For more details, see Main Article: A12GX Engine
A14 Round-port High-Swirl head
These have quench chambers (not open chambers) but instead of being used in high-compression engines, they are designed for high swirl (for better fuel economy and improved emissions). They are used with dished pistons. Unlike the swirl-port heads, these have unobstructed ports. The ports are lowered so that the charge is forced to swirl as it enters the chamber.
A12A/A14 Round-port head
Intake: 37mm
Exhaust: 30mm
Has round intake ports (like the A12 head). Casting numbers are under the valve cover area: "990" towards the rear and "454" towards the front. This is the head used on A12As and some A14s. These cannot be ported out to match the oval port heads (you'll hit a water jacket). These can be found on some late A14s, like 1980. It has two small coolant holes below the intake ports, to provide heat for the intake manifold. These came on the "GFU" and "MPG" cars (USA-market B210 and B310 fuel economy champion models).
A12A small-Oval Swirl-port head
Intake: 37mm
Exhaust: 30mm
Has an H95 cast into it, under the valve cover area, has what some call a "swirl" port has an obstruction cast into the port to cause the flow to swirl but it reduces total flow, If you look into the port, from the manifold side, you'll see a heavily shrouded port, almost half of the size, it would normally be, on an A14 head. If you try to grind out this obstruction, you will hit a water jacket and render the head useless. It too, has the coolant holes in it.
They also have a small but deep combustion chamber, hence a different dish in the piston.
A14 Oval-port "H72" head
Intake: 37mm
Exhaust: 30mm
Sometimes called the "low compression GX head", it has a casting number "H72". Has a larger 360-degree "open" combustion chamber for lower compression ratios. It does not have the coolant holes below the intake ports. The H72 head was common around 1977-1978. This H72 head is basically the same as the Nissan competition GX head, but it has a lower compression combustion chamber, and the same regular size valves as any other A-series head. It has the nice straight big oval intake ports. It is better than the A15 oval "swirl port" head, and certainly better than the round intake port A14 heads. EGR port in the exhaust ports. These can be milled .080" or more to raise compression.
So is Oval-port "H72" a good head or not? [Naukkis] says the high-compression head is a better design, and not just because of the compression (see New A series oval port head). The best combo for low compression would undoubtedly be a high-compression head used with half-dished pistons (half-flat-top, half dish), but are these available for the A-type engines?
A14 GX head
Intake: 35mm (optional 37mm)
Exhaust: 29mm (optional 30mm)
The A14 "GX" head has the large oval ports and a small heart-shaped chamber and was available from Nissan Competition aka Nismo (but now NLA). The race cylinder head, known as the "GX" head, in the Motorsport catalog, never was an stock head here in the USA. This head is a high compression head with only 29 cc chamber volume.
- 99996-H1167 Competition Cylinder Head (to 6/73)
- 99996-H1165 Competition Cylinder Head (from 6/74)
The Competition heads are "recommended for racing purposes only ... ported, polished ... competition intake (37 mm)... competitiont exhaust (30 mm)"
Presumably the newer heads only differ in the oil passage and fittings/bolt holes.
Other heads
Anyone have more information on these?
- There is apparently an A14 Oval Port GX head which flows more than the A12GX head. reference: GX Head or A15
- The A15 GX head was used by Nissan for racing. There are several different chamber shapes and sizes but just the improved flow though the oval ports is better than the stock round ones. The valve sizes should be larger and some were fitted with dual valve springs.
Cylinder Head Identification
For the cylinder head, the best way to tell which head you have is to check the casting number in the valve train area.
See Nissan Part Number Prefixes for a table of the different model to part numbers.
E.g. H23xx means the part was originally designed for B110 GX models.
- A10 may have "180", "H01", "257", "H03" or no markings at all
<li>1971-1973 A12 may have "180", "H10" or "H39". Some have no markings at all.
- A12 GX may have "H23" or "230"
- 76 Sunny trucks (A12) may have M30, G25, G61 <li>1974 A13 may have "H62" or "620"
- A14 could have several different ones, such as G32, H72 (or 728), H74, H75, H77, H78, H85, H92 or H98 depending upon year, country, and emission control design.
- M24 or 246 is A14T (twin carb engine)
<li>H85 is A12 or A13 (newer engines)
</ul>
The casting number will be the first 3 digits of the last half of the part number, as all cylinder head part numbers begin with the same 5 digits (11041). For example:
11041-H2300 or 11041-H2301 HEAD ASSY-CYLINDER A12 GX
<li>11041 is the base part number for all cylinder heads <li>"H23" means the part was first used on the B110 GX vehicle. <li>"728" is short for H728x, indicating a B210 "H72" part
references:
Measuring Combustion Chamber Volume
Here's what you need:
- A large syringe marked in CCs (without the needle, or remove the needle).
- a piece of plexiglas, big enough to cover one cylinder. Drill a small hole about 6mm from edge of the plexiglas
- some grease
Syringes are available from animal feed stores or your local chemist. Get a couple of syringes one thats about 20mls and one that has 0.1 increments which is normally about 3mls. That will cost $1-$2.
Here's how to measure:-
<li>place the head upside down as level as possible</li>
<li>put a small ring of grease around one of the combusion chambers</li>
<li>place the plexiglas over it and press it flat</li>
<li>Fill the syringe with water, and measure how many CCs it takes to fill the chamber</li>
This is also a good way to tell if the valves are sealing well. It should hold water for several hours with no visible leak. If the water leaks out, it's time to lap the valves!
Dished pistons (factory A15)Note that pistons came with different dishes according to year, country, etc.
Which Cylinder Head is "Best"?
The two main factors for peak horsepower:
-
<li>combustion chamber design: closed chamber "heart-shaped" is more efficient than open chamber</li>
<li>port flow: oval is better than round for high-rpm use, and larger valves can be useful</li>
NOTE: Don't confuse "open chamber" for a hemi-style chamber. Yes, both are 360-degree 'open', but the term "hemi" refers to valves at 45-degrees to each other (all A-type engines use valves parallel to each other). The "open" chamber is not inherently better flowing, but is used to reduce compression for lower NOx emissions.
Some say to start with the A12GX Engine head due to its high-compression chamber. Adding bigger valves is good for high-rpm power. Others say a ported standard A12 head will flow as much as the A12GX, but this doesn't increase the compression.
GX heads are not always easy to find, though they pop up for sale every year.
"The best head of the easily available variety, IMO is the H89 head from the A15." - A14Force.
Or you could use the H72 head, and shave/mill it to increase compression.
The A14GX (high-compression) head is probably the best all-around head: big valves, big ports and an efficient chamber design. But you probably cannot find this Competition head ... unless you already have one.
Aftermarket piston styles vary (flat-top or dished, and aftermarket popup/domed pistons). With dished pistons, the pistons can be shaved and the block milled (up to 0.090 inch) to make high compression "flat-top pistons".
On the other hand, for a supercharged motor low compression is best, because you can use more boost and gain more power than is lost due to the low compression.
-
<li>closed chamber head with a half-dished piston is probably best due to the efficient "quench" combustion</li>
For a low-rpm 'grunt' engine, or for maximum fuel economy, you'll want:
-
<li>Small ports</li>
<li>large valves with an A14 or A15, small stock-size valves with an A10 or A12 (anyone have another opinion?)</li>
<li>closed chamber or swirl-port head</li>
So which is better for a street engine?
-
<li>High compression engine: pay 15% premium for high-test fuel but get better mpg</li>
<li>Low compresion engine: buy the inexpensive petrol, but get worse mpg</li>
Modifying a Head
variable cam gear
Timing Cover for variable cam gear
anti-heat coating
O-ringingPort and Polish
See: Head Porting
Part Numbers
B110
The following part numbers are from the B110 Japanese Domestic Model parts catalog (Nov. 1971), unless otherwise noted.
A12
Intake valves: 29mm 13201-H1000
Exhaust valves: 35mm 13202-H18000
11041-H1001 HEAD ASSY-CYLINDER A12 except GX 11041-H1003 11041-H1003 HEAD ASSY-CYLINDER A12 except GX 11041-H1005 11041-H1005 HEAD ASSY-CYLINDER A12 except GX
All of these are replacement-equivalents
A12GX (dual valve springs)
Intake valves: 13201-H2300
Exhaust valves: 13202-H2300
Combustion Chamber: 29cc (compression ratio 10:1 with flat-top pistons)
11041-H2300 HEAD ASSY-CYLINDER A12 GX 11041-H2301 11041-H2301 HEAD ASSY-CYLINDER A12 GX
B210
From the B210 Japanese Domestic Model parts catalog (Jul 1978)
A12S Sedan & Coupe
Intake valves: 13201-H2300
Exhaust valves: 13202-H7400
11041-H7401 HEAD ASSY-CYLINDER A12S S,K -7612 11041-H7403 11041-H7403 HEAD ASSY-CYLINDER A12S S,K 7710-
A12S Van
Intake valves: 29mm 13201-H1000
Exhaust valves: 13202-18000
11041-M3000 HEAD ASSY-CYLINDER A12S V -7612 11041-M3001 11041-M3001 HEAD ASSY-CYLINDER A12S V 7701-
A14S
Intake valves: 13201-H6200
Exhaust valves: 13202-H6200
11041-H7500 HEAD ASSY-CYLINDER A14S V 11041-H7860 HEAD ASSY-CYLINDER A14S V
A14T (twin carb)
From the B120 Japanese Domestic Model parts catalog (Oct 1997)
Intake valves: 13201-H6200
Exhaust valves: 13202-H6200
11041-M2460 HEAD ASSY-CYLINDER A14T (dual valve springs)
A12S
Intake valves: 29mm 13201-H1000 replaced by 13201-H2300 (from 8504)
Exhaust valves: 35mm 13202-H18000 replaced by 13202-H7400 (from 8504)
11041-M3000 HEAD ASSY-CYLINDER 7510-7803 A12S 11041-H3001 11041-M3001 HEAD ASSY-CYLINDER 7804-7907 A12S 11041-G2560 11041-G2560 HEAD ASSY-CYLINDER 7908-8109 A12S 11041-G2561 11041-G2561 HEAD ASSY-CYLINDER 8110-8910 A12S 11041-G6100 HEAD ASSY-CYLINDER 8910- A12S
B310
From the B310 Japanese Domestic Model parts catalog (Nov. 1983)
A12S Van
Intake valves: 29mm 13201-H1000 (1971 B110)
Exhaust valves: 35mm 13202-H18000 (1971 B110)
11041-M3001 HEAD ASSY-CYLINDER A12S.V N-7907 11041-G2560 11041-G2560 HEAD ASSY-CYLINDER V.A12S 7910-8010 11041-G2561 11041-G2561 HEAD ASSY-CYLINDER V.A12S 8011-
All three of these are replacement-equivalents
A12S Sedan & Coupe
Intake valves: 13201-H2300 (1971 B110 GX engine)
Exhaust valves: 13202-H7400
11041-H8500 HEAD ASSY-CYLINDER A12S.S,K N-7909 11041-H8501 11041-H8501 HEAD ASSY-CYLINDER S,K.A12S 7910-8010
Both of these are replacement-equivalents
A13S
Intake valves: 13201-H2300 (1971 B110 GX engine)
Exhaust valves: 13202-H7400
11041-H8503 HEAD ASSY-CYLINDER A13S 8011-
A14, A15
Intake valves: 13201-H6200
Exhaust valves: 13202-H6200 replaced by 13202-H8900
11041-H7861 HEAD ASSY-CYLINDER A14S.V N-7806 11041-H7863 11041-H7863 HEAD ASSY-CYLINDER A14S.V 7807-7909 11041-G3202 11041-G3202 HEAD ASSY-CYLINDER V.A14S 7910-8010 11041-G3203 HEAD ASSY-CYLINDER V.A14S 8011- 11041-H8900 HEAD ASSY-CYLINDER S,K.A14S 7811-7903 11041-H8901 11041-H8901 HEAD ASSY-CYLINDER S,K.A14S 7811-7903 11041-H8904 11041-H8904 HEAD ASSY-CYLINDER A15S 8011- S,K.A14S 7904-8010
A14E & A15E (dual valve springs)
Intake valves: 13201-H6200
Exhaust valves: 13202-H6200 replaced by 13202-H8900
11041-H9200 HEAD ASSY-CYLINDER A14E N-7810 11041-H9201 11041-H9201 HEAD ASSY-CYLINDER A14E 7811-7903 11041-H9202 11041-H9202 HEAD ASSY-CYLINDER A14E 7904-7907 11041-H9204 11041-H9204 HEAD ASSY-CYLINDER A14E 7908-8010 A15E 8011-
All of these are replacement-equivalents
Datsun Cherry Heads
The Datsun Cherry model family was Datsun's first front-wheel-drive line and includes the E10, F10 and N10 models, a.k.a. Pulsar and includes Datsun 310.
A10 from E10
Intake valves: 29mm 13201-H1000
Exhaust valves: 35mm 13202-H18000
11041-M0102 HEAD ASSY-CYLINDER A10
A12S from E10
Intake valves: 29mm 13201-H1000
Exhaust valves: 35mm 13202-H18000
11041-H1503 HEAD ASSY-CYLINDER A12S
A12T from E10 (dual valve springs)
Intake valves: 13201-H2300
Exhaust valves: 13202-H2300
11041-M0801 HEAD ASSY-CYLINDER A12T
A12 from F10 Sedan & Coupe
Intake valves: 13201-H2300
Exhaust valves: 13202-H7400
11041-H7401 HEAD ASSY-CYLINDER A12S S,K
A12 from F10 Van
Intake valves: 29mm 13201-H1000
Exhaust valves: 35mm 13202-H18000
11041-M3000 HEAD ASSY-CYLINDER A12S V
A14S from F10
Intake valves: 13201-H6200
Exhaust valves: 13202-H6200
11041-7502 HEAD ASSY-CYLINDER A14S
A14T from F10
Intake valves: 13201-H6200
Exhaust valves: 13202-H6200
11041-M2460 HEAD ASSY-CYLINDER A14T
A12S from N10 Van
Intake valves: 29mm 13201-H1000
Exhaust valves: 35mm 13202-H18000
11041-M3001 HEAD ASSY-CYLINDER 11041-G2560 11041-G2560 HEAD ASSY-CYLINDER
A12AS from N10
Intake valves: 13201-H2300
Exhaust valves: 13202-H7400
11041-H8500 HEAD ASSY-CYLINDER A12AS 11041-H8501 11041-H8501 HEAD ASSY-CYLINDER A12AS 11041-H8503 11041-H8503 HEAD ASSY-CYLINDER A12AS
A14S from N10 Van
Intake valves: 13201-H6200
Exhaust valves: 13202-
11041-G3202 HEAD ASSY-CYLINDER 11041-G3203 11041-G3203 HEAD ASSY-CYLINDER 11041-H7863 HEAD ASSY-CYLINDER
A14S from N10 P
Intake valves: 13201-H6200
Exhaust valves: 13202-
11041-H8900 HEAD ASSY-CYLINDER 11041-H8902 11041-H8902 HEAD ASSY-CYLINDER 11041-H8904 11041-H8904 HEAD ASSY-CYLINDER
A14E from N10 (dual valve springs)
Intake valves: 13201-H6200
Exhaust valves: 13202-
11041-H9200 HEAD ASSY-CYLINDER 11041-H9202 11041-H9202 HEAD ASSY-CYLINDER 11041-H9204 11041-H9204 HEAD ASSY-CYLINDER
Nissan Competition
From the 1984 Nissan Competition Catalog:
CYLINDER HEADS & COMPONENTS (A-SERIES)
- 11041-H2302 GX CYLINDER HEAD (TO 6/73) For use with any A-series engine built up to 6/73. It has a 29cc combustion chamber and, due to its large intake port size, must be used with either the GX or Mikuni/Solex intake manifold. Valve size is 35mm/1.38" (intake) and 29mm/1.14" (exhaust)
- 11041-H5703 GX CYLINDER HEAD (FROM 7/73) Specifications are the same as 11041-H2302. For A-series engines built from 7/73
- 99996-H1167 COMPETITION CYLINDER HEAD (TO 6/73) This cylinder head is recommended for racing purposes only. Must be used with either the GX or Mikuni/Solex intake manifold. Completely ported, polished and fitted with competition intake (37mm/1.46") and exhaust (30mm/1.18") valves. For A-series engines built up to 6/73
- 99996-H1165 COMPETITION CYLINDER HEAD (FROM 7/73) Specifications are the same as 99996-H1167. For A-series engines built from 7/73
- 11056-H2301 GX HEAD BOLT Torque spec = 58 ft/lbs (9 needed)
- 11057-H2301 GX HEAD BOLT (TO 6/73) Torque spec = 58 ft/lbs (1 needed)
- 11057-H5700 GX HEAD BOLT (FROM 7/73) Torque spec = 58 ft/lbs (1 needed)
- 11044-M0821 COMPETITION HEAD GASKET Gasket has a bore diameter of 79mm/3.11", an uncrushed thickness of 0.8mm/ 0.032" and displaces 3.9cc's
Hollander Interchange
North American-Market Cylinder Heads (reference Hollander interchange 1980)
No. 183 Datsun 1200 (B110) 71-73 A12
11041-H1001 to 5/71 obs 11041-H3900 6/71-12/72 obs 11041-H3901 1/73-2/73 obs 11041-H3902 3/73 & up
No. 1367 Datsun B-210 (B210) 1974 A13
11041-H6200
No. 1370 Datsun B-210 (B210) 1977 A14
11041-H78261 or 11041-H7760
No. 1375 Datsun B-210 (B210) 75-76 A14 & Datsun F10 1976
11041-M4900
No. 1376 Datsun F10 1977-78
11041-H7660
No. 2641 Datsun 210 (B310) 1979 Ex. California A14 & A15
11041-H7702
No. 2642 Datsun 210 (B310) 1979 California A14 & A15
11041-H9162
No. 2742 Datsun 310 (N10) 1979
11041-H7762
DOHC Heads for A-series
GM Vauxhall DOHC head on A block
GM Opel/Daewoo/Vauxhall Ecotech HeadNissan DOHC Head
(GA16 ?)
Nissan DOHC HeadMazda b6
KA24E
Osgiken
E15 SOHC
Will the new E-series heads might fit on the A12 engine? Note that the 1982 E15 engine design is based on the A15 engine:
-
<li>Same bore & stroke
<li>Same bore pitch (82.5mm - 90mm - 82.5mm)
<li>Lighter casting
<li>Similar head gasket
<li>E15 is overall shorter to fit transverse applications (FWD)
<li>Crossflow head with semi-spherical chambers improves on A15: HP and torque are both up 3%
<li>The E15 uses a jackshaft "in the area where the camshaft is mounted on the A-series engine" to drive the fuel pump and oil pump (the distributor is driven off the front of the cam)