Main Menu

Home News Forum Photo Album Tech Wiki Downloads Web Links Polls FAQ Members Map

Fast Search

Slow Search

Google Ad

Revision as of 04:25, 16 October 2012

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). An exception to the above is the work AY12 head. It is cast in aluminum and unlike the BMC A-series bathtub chamber design, the Datsun A-series uses a more modern wedge-shaped chamber with inclined valves.

1 Application
2 Cylinder Head Identification
3 Early A Engine
- 3.1 Round Port
- 3.2 Large Oval Port
  - 3.2.1 A12GX Head
  - 3.2.2 Early A12T Head
4 Late A Engine
5 Nissan Competition Catalog
- 5.1 Competition Head
6 Other heads
7 High Roof Heads
8 Measuring Combustion Chamber Volume
9 Which Cylinder Head is "Best"?
- 9.1 So which is better for a street engine?
10 Modifying a Head
11 Part Numbers
12 DOHC Heads for A-series
13 AY12 Racing Head

Application

For application by Datsun model, see Cylinder Head Part Numbers.

Cylinder Head Identification

Most A-engine heads do not have unique casting numbers. For a process of identification see Cylinder Head Identification. The article also discusses various distinguishing features of the various cylinder heads and includes many photos.

Early A Engine

The 1967-1973 heads provide oil to the rocker arm shafts in different locations than 1974-up, so when fitting a newer head you may need to redrill the oil passage.

Round Port

All early (pre-1974) A-series round-port engines uses the following
* 35 mm Intake valves 13201-H1000 
* 29 mm Exhaust valves 13202-18000 
* Dry type manifold 
* 14035-18000 GASKET-manifold to head
* Original manifold bolt pattern

A10 head

The 1970 B10 is 9.0:1, same as the B110 ratio. Yet they use the exact same head. This indicates the B10 piston dish is 20% larger.

* (optional) Rally Springs (dual valve springs) 
* Early heads have non-A12 fittings
* Late A10 heads are same as A12

B10 Coupe Head

B10 Coupe with A10 engine had different part number. It is unknown how it differs from the regular Datsun 1000 cylinder head.

It is fitted with flattops pistons (same as the Hi-Gas A12GX pistons), and a dual-outlet exhaust manifold.

A10 M01 Head

11041-M0100 HEAD ASSY-cylinder E10 JDM
11041-M0101 HEAD ASSY-cylinder E10 JDM (from '72-1)
11041-M0102 HEAD ASSY-CYLINDER E10 JDM
11041-M0105 HEAD ASSY-CYLINDER N10 EUR 0878-0781 
11041-M0104 HEAD ASSY-CYLINDER N10 EUR 0878-0781

A12 H10 Head

H10 head has no casting numbers
* JDM B110
* USA B110 Early 1971 model (until April 1971) 
* Closed Chamber

Known in SCCA racing circles as the "H Production" head, legal alternative for H39 head.

See discussion: Are these A series GX or comp heads? Experts needed!

Some say a ported and polished standard A12 head with larger valves fitted flows about the same as a standard GX head. See head trivia.

A12 H15 Head

From Nissan Cherry E10

A12 H39 Head

* USA B110, from April 1971
head has no casting numbers
* Same as H10 head, but with open chambers
* Compression ratio 9.0:1 with dished pistons

Open Chamber heads are most common in USA. They were fitted mid-1971 to remove the temperature-spiking "quench" area therefore reducing NOx (nitrogen oxides) emissions.

Large Oval Port

All Large Oval-port engines use the following:
* 35 mm Intake valves 13201-H2300 
* 29 mm Exhaust valves 13202-H2300 
* Wet type manifold 
* 14035-H2300 GASKET-manifold to head
* Original manifold bolt pattern

A12GX Head

Cast "JAPAN" and "NISSAN"
* Large Oval Ports (30 x 36 mm)
* Same size valves as A10 & A12 engine

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 ratio 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

Early A12T Head

Cherry E10 model has a head same or very similar to the A12GX head (11041-H2300):

 11041-M0800

Late A Engine

1974-up A Engine Redesign heads provide oil to the rocker armshafts in different locations than earlier heads. The new heads do not have the oil passage on their face, so when swapping into earlier blocks you need to drill the oil passage.

Round Port

Round ports heads were used by all A12s & some A14s and one A15.

Some A12s use the original bolt pattern while other A12s have the new-type bolt pattern.
Valve sizes vary

H81

Sweden emissions head.

* Intake valves: 35mm 13201-H1000
* Exhaust valves: 29mm 13202-H1000
Gasket 14035-18000
* Dry type
* Original bolt pattern
* round ports

A12 M30 Head

The new-style A12 head (without oil passage on face of head), Low-po Van/Truck engine. Used in Europe cars except Sweden.

B120 Sunny Truck 7510-7907
B210 JDM Late A12 Van
B310 JDM A12S Van -7909
F10 JDM A12S Van
N10 JDM A12S Van
EUR N10 A12S except SWE
* Intake valves: 35mm 13201-H1000
* Exhaust valves: 29mm 13202-18000
* Dry manifold
* Closed Chamber
* Cast "M30" 
* Original bolt pattern
14035-18000 Manifold gasket

M30-060

M30-064

H74

H74 Head was fitted to late JDM B210 Van (from October 1975)
* Intake valves: 35mm 13201-H2300
* Exhaust valves: 29mm 13202-H7400
* Round Port
* Dry Intake
* New intake bolt pattern
* 14035-H7400 Gasket-head to manifold
11041-H7401 HEAD ASSY-CYLINDER A12S S,K -7612
11041-H7403 HEAD ASSY-CYLINDER A12S S,K 7701-

A12 G25 Head

* G25 cast number
* Dry manifold 
* Closed Chamber 
* New bolt pattern 
11041-G2560 HEAD ASSY-CYLINDER 7908-8109
11041-G2561 HEAD ASSY-CYLINDER 8110-8910

G32

* Round Port A14
* Intake valve: 37mm 13201-H6200
* Exhaust valve: 30mm 13202-H6200
 replaced by 13202-H8900 7907-
* 14035-H7201 GASKET-MANIFOLD to CYLINDER HEAD
* 14035-H7400 GASKET-MANIFOLD TO CYLINDER HEAD A14S.V 7906-
11041-G3202 HEAD ASSY-CYLINDER A14S.V JDM A10 7907-

A12 G61 Head

11041-G6100 HEAD ASSY-CYLINDER B120 8910-
Wet manifold 
Closed Chamber, deep shroud
New bolt pattern 
58 hp

728

A14 Round Port head, high swirl type, for the FU Engine 1977-1979.

11041-H7281, 11041-H7282, 11041-H7283
Round Port, Large Valves
Dry manifold
Closed chambers
Intake: 37mm
Exhaust: 30mm
14035-H7400 GASKET-MANIFOLD TO CYLINDER HEAD

728-402

Lowered-port high-swirl design for the FU Engine. 728 heads were also used on 1978-1982 Canada models (B210 & B310).

These have quench chambers (closed 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 for 8.5:1 in 1977 and 9.0:1 in 1978 FU (4mm dish or 5mm dish). 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.

H990

For 1980, wet intake replaced dry intake. USA FED A12/A14/A15 round port, wet intake, new bolt pattern.

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. These cannot be ported out to match the oval port heads (you'll hit a water jacket). It has two small coolant holes below the intake ports, to provide heat for the intake manifold. These came on the "FU" and "MPG" cars (USA-market B310 fuel economy champion models).

Has "990" cast near #4 cylinder and "415" at the #1 end

H991

USA A12A 
CAL A14/A15

H916

CAL A14/A15

H85

* Intake valves: 35mm 13201-H2300
* Exhaust valves: 13202-H7400
* Round Port
* Intake Water Ports
* New intake bolt pattern

* 11035-H8501 GASKET-MANIFOLD TO CYLINDER HEAD A12S.S,K
11041-H8500 HEAD ASSY-CYLINDER A12S.S,K B310 JDM N-7909 11041-H8501
11041-H8501 HEAD ASSY-CYLINDER S,K.A12S B310 JDM 7910-8010

* 11044-H8660 GASKET-MANIFOLD TO CYLINDER HEAD A13S, A15 JDM 8011-
11041-H8503 HEAD ASSY-CYLINDER A13S 8011-

A14 H78 Round Port Head

A14: (H78) Round Port, dry manifold, large valve A14S Van
* 11044-H7400 GASKET-MANIFOLD TO CYLINDER HEAD
11041-H7863 HEAD ASSY-CYLINDER A14S V A10 7807-7906

Small Oval Port

A13 H62 Head

The 1974 A13 engine for north america featured small oval ports.

H95 Small-Oval Shrouded-port Head

Also see: H95

Used on all USA engines 1981-1982 (A12A, A14 and A15)
Intake: 37mm, 100.0 mm
Exhaust: 30mm, , 100.0 mm
- All other A-series valves are 103.8 mm long
peanut-shaped combustion chambers
Small-oval ports, guide is shrouded
wet intake
14035-H8901 manifold gasket (same as Larg Size ports)

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.

Regular Oval Port

The A14/A15 Oval-port Heads include large 37 mm intake valves and 30 mm exhaust valves.

There are many part numbers, which differ for year, emission control, accessory fittings, coolant passages, etc.
These heads first appeared with the 1975 A14 engine.
Open Chamber versions can can be milled .080" or more to raise compression.

Oval-Port heads include:

H72: Dry, Large Oval, Open Chamber. The original A14 head, designed for USA market. With Air Pump passage
H77: Same as H72 but drilled for more emission controls
H75: Same as H72 but for non-USA market w/o Air Pump
H89: Closed Chamber Wet manifold use in B310
M24: For twin-carb A14T, similar to H89 but with dual-valve springs

G51

Late model Vanette large-bore head (A14/A15)

14035-H8901 Gasket-manifold to head
* Wet Type 
* 14035-05H01
* Intake valves: 37mm 13201-H6200
* Exhaust valves: 30mm 13202-H6200 
11041-G5100 HEAD ASSY-CYLINDER GC22 EUR.LHD A15 0986-1190
11041-G5100 HEAD ASSY-CYLINDER C22 JDM
11041-G5101 HEAD ASSY-CYLINDER C22 JDM
11041-G5200 HEAD ASSY-CYLINDER GC22 EUR.LHD A15 1190-

H72

The original A14 head. Designed for north america, it has open combustion chambers and is drilled for air pump passages.

B210 USA '75-0777
* Cast "H72" and "108"
* Cast "H72" and "104" is H77
* Open chamber
* Dry Type
* Oval Ports
* Air-exhaust passage
14035-H7200 Gasket-manifold to head

Sometimes erroneously called the "low compression GX head", it has a casting number "H72". Has a larger 360-degree "open" combustion chamber for reduced emissions. It does not have the coolant holes below the intake ports, so uses a 'dry' type inlet manifold. It has the nice straight big oval intake ports. It is better than the A14 oval "swirl port" (H95) head, and certainly better for high RPM use than the round intake port A14 heads. Air pump galley drilled from front face all the way back through, intersecting all the exhaust ports.

Open Chamber design

So is Oval-port "H72" a good head or not? [Naukkis] says the "high-compression" (closed chamber) head is a better design, and not just because of the compression (see New A series oval port head). The quench design of the combustion chamber is more efficient. 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?

Note air pump passage

Note the "extra water port" at the rear, plugged in 1975, but fitted with a sensor/switch in others:

The original A14 head (H72) has the oil boss casting like early A12 heads, only it is not drilled & plugged:

H75

A14: (H75) 
JDM Late B210 A14S Van
A10 JDM A14S.S,K -7803
* 14035-H7200 GASKET-MANIFOLD TO CYLINDER HEAD
* Intake valves: 37mm 13201-H6200 
* Exhaust valves: 30mm 13202-H6200 
* Oval Ports 
* Dry Intake
* Open Chamber design, 31cc

[1]

H77

Same as H72 but with different emission provision
* Cast "H72" and "104"
* rear port face boss (for water sensor) is undrilled
* B210 USA A14S 0877- non-5speed models
* B310 USA FED 1980 model year
* N10 USA A14S Federal 0878-0779
* Open chamber
* Dry Type
* Oval Ports
* Air-exhaust passage
14035-H7200 Gasket-manifold to head

A14 H78 Oval Port Head

A14: (H78) Oval Port, dry manifold, large valve A14S Van
* 11044-H7860 GASKET-MANIFOLD TO CYLINDER HEAD
11041-H7860 HEAD ASSY-CYLINDER A14S V B210
11041-H7861 HEAD ASSY-CYLINDER A14S V A10 -7806

H89

Oval-port Closed-Chamber was fitted to A14-powered B310 Coupe and Sedan in the JDM market (but not to Van (wagon). C120 came with A15 engine and H89 head. Closed-chamber is a non-emissions controlled head (no EGR). It is sometimes called "High Compression", but the compression is about the same as the open chamber (H72) head -- the compression is controlled by the piston dish, not the head.

Closed Chamber
Oval Port
Intake Water Ports
New intake bolt pattern

H99

* USA N10 A14S 0879-0780
* Similar to FU Engine and late model G61 A12
* Round Port for A14
* Closed chamber
* Wet type

M24

M24 Head from A14T engine
* Intake valves: 37mm 13201-H6200
* Exhaust valves: 30mm 13202-H6200
* Dual valve springs
* Oval Ports (smaller than GX, same size as standard A14)
** Intake-to-Head gasket 11044-H7200
11041-M2460 HEAD ASSY-CYLINDER A14T B210 JDM

M66

A15S new type combustion 
* USA N10 (Pulsar) "Datsun 210" 0880-0781
* Wet type
* Oval Port
* INTAKE 35mm: 13201-H9500
* EXHAUST 30mm: 13202-H9500
* 14035-H8901 Gasket-manifold to head
** interchangeable with 14035-05H01
11041-M6600 HEAD ASSY-CYLINDER

M49

Medium Oval Port

28x32 intake ports were used by A14E and A15E EFI heads.

H92

The EFI heads. Fitted to A14E and A15E in Asia-market B310s and N10s.

N10 JDM A14E
B310 JDM A14E, A15E
* Intake valves: 37mm 13201-H6200
* Exhaust valves: 30mm 13202-H6200 replaced by 13202-H8900 7910-
* Dual valve springs
14035-H9201 Manifold gasket
* Wet manifold
* Medium Oval Ports with notch for injector
* 28x32 mm with injection cutout of extending up to 40mm 
* compare to standard A14: 28x34

Large Oval Port

H57

Late A12T from B210 Sunny and E10 Cherry. Appears to be the same as the earlier A12T engine, except the head has no oil passage on the face of the head.

Nissan Competition Catalog

From 1984 Nissan Competition Catalog

* 11041-H2302 GX CYLINDER CYLINDER HEAD (TO 6/73)
* 11041-H5703 GX CYLINDER HEAD (FROM 7/73) 
** This is actually the A12T head from B210
* 99996-H1167 COMPETITION CYLINDER HEAD (TO 6/73)
* 99996-H1165 COMPETITION CYLINDER HEAD (FROM 7/73)

Competition Head

99996-H1165 pictured

* Intake: 35mm (optional 37mm)
* Exhaust: 29mm (optional 30mm)

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.

The Competition Head has the large oval ports and a small heart-shaped chamber (Closed Chamber) and was available from Datsun Competition, later called Nissan Competition and then Nismo. The part is unforunately now NLA (No Longer Available). This race cylinder head reported has the same 29 cc chamber volume as the A12GX head.

Sometimes the Competition Head is erroneously called the A14 "GX" head because it is similar to the GX casting but fitted with the A14 size valves.

99996-H1167 Competition Cylinder Head (to 6/73)
99996-H1165 Competition Cylinder Head (from 6/74)

Presumably the difference in the two Competition Head part numbers only differ in the oil passage and fittings/bolt holes.

The Competition heads are "recommended for racing purposes only ... ported, polished ... competition intake (37 mm)... competition exhaust (30 mm)" -- in other words, the same valve sizes as regular A14 heads. However, the valves are tulip-machined for better flow.

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

An 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.

High Roof Heads

High-port heads. Are these the Competition Heads? Or some other kind of racing-only head?

Also see: Cylinder Head Modifications Raised-Ports.

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:

place the head upside down as level as possible
put a small ring of grease around one of the combusion chambers
place the plexiglas over it and press it flat
Fill the syringe with water, and measure how many CCs it takes to fill the chamber

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:

combustion chamber design: closed chamber "heart-shaped" is more efficient than open chamber
port flow: oval is better than round for high-rpm use, and larger valves can be useful

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.

closed chamber head with a half-dished piston is probably best due to the efficient "quench" combustion

For a low-rpm 'grunt' engine, or for maximum fuel economy, you'll want:

Small ports<
large valves with an A14 or A15, small stock-size valves with an A10 or A12 (anyone have another opinion?)
closed chamber or swirl-port head

So which is better for a street engine?

High compression engine: pay 15% premium for high-test fuel but get better mpg
Low compresion engine: buy the inexpensive petrol, but get worse mpg

Modifying a Head

See main article: Cylinder Head Modifications

See: Head Porting (Port and Polish)

Part Numbers

See Cylinder Head Part Numbers

DOHC Heads for A-series

See DOHC Heads

AY12 Racing Head

There was one exception: The race-only AY12 cylinder head:

Retrieved from "http://datsun1200.com/modules/mediawiki/index.php?title=A-series_Cylinder_Heads"

A-series Cylinder Heads

Revision as of 04:25, 16 October 2012

Contents

Application

Cylinder Head Identification

Early A Engine

Round Port

A10 head

B10 Coupe Head

A10 M01 Head

A12 H10 Head

A12 H15 Head

A12 H39 Head

Large Oval Port

A12GX Head

Early A12T Head

Late A Engine

Round Port

H81

A12 M30 Head

H74

A12 G25 Head

G32

A12 G61 Head

728

H990

H991

H916

H85

A14 H78 Round Port Head

Small Oval Port

A13 H62 Head

H95 Small-Oval Shrouded-port Head

Regular Oval Port

G51

H72

H75

H77

A14 H78 Oval Port Head

H89

H99

M24

M66

M49

Medium Oval Port

H92

Large Oval Port

H57

Nissan Competition Catalog

Competition Head

Other heads

High Roof Heads

Measuring Combustion Chamber Volume

Which Cylinder Head is "Best"?

So which is better for a street engine?

Modifying a Head

Part Numbers

DOHC Heads for A-series

AY12 Racing Head