Datsun 620 Pickup Truck ,¡|The 620 Resource|¡, ->The SSS cylinder head

WHAT IS A SSS CYLINDER HEAD?

The SSS cylinder head (#11041-U0600A) was part of the SSS package available in Datsuns outside of the North American market. It has 1.65" intake valves, 1.38" exhaust valves and 1.50" intake ports. These heads are sought after by performance enthusiasts because of their small combustion chambers. Noticed the heart shape of the chambers in the photo below (OK, it's the shape of a diseased heart) It is also referred to as the "peanut head"or "closed chamber head". Perhaps the "kidney bean" head would be more appropriate. When used with flat-top pistons, these heads were good for a static compression ratio of 9.5:1 (according to the factory manuals) when used with an L-16. Keep in mind that the compression will be higher if the head has been surfaced (likely) and the block has been bored. FYI, the uncut surface-to-surface thickness of the L-series cylinder head is 107.9mm/4.248". There were a few variations of the SSS cam. The most common version had .410" lift and 248 degrees duration. This is the same as the L-20B cam that came to the U.S.

Other cylinder head options:

While the original SSS head (casting # 219) is very rare today, there are other L-series cylinder heads that have the same combustion chambers. As a result, these other heads are often referred to as SSS heads. The "peanut" combustion chamber volume was approximately 41cc. These heads will sometimes have smaller (1.30") exhaust valves and will always have smaller intake ports (1 1/4" and 1 3/8") These smaller intake ports are a plus for a street engine, as the 1.50" SSS intake ports are a bit on the large side. However, if you plan on using the factory SSS SU intake setup, it would be wise to port match the head to the SSS intake manifold (which is 1.50").
Most Datsuns imported into this country came with an open-chamber cylinder head (see below). The open-chamber heads found on L-18 and L-20B's had combustion chambers of approximately 45.3cc. Most of the open-chamber heads found on the L-16 had a chamber volume of 38.5cc.

For a performance engine, a cylinder head with peanut chambers is preferable. The design is more efficient and less prone to detonation. There are applications where the open-chamber design would be a better choice. Large displacement hybird engines such as the L-22 or L-23 would be good examples.

Cylinder head castings:

The following is a list of cylinder head castings and their corresponding chamber shapes. Keep in mind that list is not etched in stone. For example, the A87 casting can be either open or closed chamber design. The only way to tell is to pull the head. To find your casting number, look just below the #1 and #2 spark plugs. The number will be cast right where the head meets the block.

Casting #	Chamber type	Description
A87	open or closed	found on many L-18 and L-20B's. The "domestic" version usually came with open chambers. Many of the "used Japanese import" engines came with the peanut version of this head. Large quantities of these used engines were imported in the 80's, so the peanut version is fairly common. These heads usually have 1.25" intake ports and square exhaust ports. 1.65" intake valves. Exhaust valves can be 1.38" or 1.30"
W53	closed (with some exceptions)	This head is from the Japanese market. Some of these castings are for factory fuel injected engines and have notches in the intake ports to accommodate injectors. 1.25" intake ports and square exhaust ports. 1.65" intake valves and 1.38" exhaust valves.
219 11041-V9182	closed	The true SSS head from imported used engines or ordered from the Datsun comp. catalog. Later versions could be ordered from the catalog with a V912 casting. 1.50" intake ports, square exhaust ports. 1.65" intake valves and 1.38" exhaust. These are hard to find. Any of the other closed chamber heads can be "converted' to this design by simply opening up the intake port to 1.50" (if that's desired) Some of these heads are marked "A87" on the side, but have "219" cast at the front of the head, just below the timing chain inspection plate.
210 (some have no number) 11041-N2202 SV	open (with rare exceptions)	This is the head that came stock on the 510. Tiny 1.125" intake ports, square exhaust ports. 1.50" intake valves and 1.30" exhaust valves. There have been variations reported on the valve sizes. This head is believed to be originally designed for the L-13, and engine never imported to the U.S. I know of one that has the peanut (closed) chamber with 37cc displacement. The earliest versions had more of a "semi-open" chamber design but later examples were the open chamber design. These heads are usually avoided on performance applications.
U67	open	The stock cylinder head for many L-20B's. 1.375" intake ports, square exhaust ports. 1.65" intake and 1.38" exhaust valves.
U60	open	Identical to the U67 head, this number has been found on very early L-20B's. It seems to be fairly rare.
W58 11041-W5880	open(with rare exceptions)	This is the L-20B smog head usually found on '77 and later engines. 1.375" intake ports with ROUND exhaust ports. These exhaust ports have steel liners that help burn off emissions. I know of one of these castings that has closed chambers. These heads don't flow well and are avoided for high-performance applications.
N56	open(?)	This is an emissions head that appears to be identical to the W58 casting. The combustion chamber design has not been verified yet, but is probably open.

I want to thank Jason Gray for helping me update this page.

- Brendan Parrott

Page last updated on Wednesday, August 20, 2008

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