On 10/14/2012, Mike Greener in Thomasville, Georgia, USA wrote:
"My cylinder head is marked 'Nissan'. I'm wondering if I need to be concerned about the Japanese head on my British engine, or just forget it. Is this a common thing? The PO told me the engine was 'rebuilt'. I'm guessing a cracked head, and the rebuilder just stuck on what was cheapest. Any chance Nissan heads were made to run on modern fuel"?

Nissan cylinder head

Nissan was a well known name building Japanese war planes during WW-II. After the war, Nissan was a poison name for international trade into the Allied countries, so cars sent to North America wore the Datsun brand name. 40 years later, Nissan phased out the Datsun brand in March 1986, going back to the native company name Nissan. Datsun was created in 1931 by the DAT Motorcar company to market its smallest cars. In Japan the cars and engines and trucks and most everything else they built during and after WW-II were Nissan. Very recently Nissan is considering reviving the Datsun name for a line of low priced cars for emerging markets. Apparently this is to segregate the cheap cars so as not to tarnish the good name of Nissan (which is supposed to be now related to an image of quality).

For prerequisite you should review VT-103 -- Non Production VARIANTS of MGA, and VT-103D -- VARIANTS - Datsun 1000 through Datsun 240Z. This second article is an interesting bit of history about rebuilding Japan after World War II, and what happened when the British lent a hand and licensed Austin technology for the Japanese to build engines and other mechanical parts and even clone complete cars.

You might also review BE-100 -- B.M.C, M.G., & Morris ENGINE CODES. Here you may find at least 75 different engine codes based on the Austin B-series engine block. Also see BE-100 -- CYLINDER HEADS for MGA, where you may find at least a dozen different casting numbers for cylinder heads that will physically fit on the B-series engines.

The point of all this is one of the Nissan cylinder heads that may sometimes show up on an engine in an MGA. There was quite a range of Nissan car models, commonly known as Datsun in North America, that had cylinder heads that can be a direct bolt-on substitute for an MGA engine. In the late 1960's through most of the 80's when MGA had notably low resale market value, it was common to piece one together with whatever parts were available on the cheap. This occasionally included a Japanese built cylinder head from Datsun cars and trucks, typically pulled out of a junk yard (auto recycling yard in modern jargon). It is not nearly as common today when MGA are more valuable and the old Datsun vehicles are mostly gone, but some of these substitute examples still survive.

Most of these Datsun cars (1000 through 310 series) used a cylinder head that is interchangeable on the MGA. With time Nissan upgraded engines and did more of their own design work. By the late 60's or early 70's I suppose the interchangeable cylinder heads may have ceased production in Japan. This was all before introduction of low lead or unleaded fuel, so none of the Nissan heads are no-lead heads. But don't let that bother you. Just go ahead and drive it with modern motor fuel, no additives. If/when you have enough miles on it to need a valve job, then install have the machine shop install hardened steel valve seats to make it a no-lead head. Bronze valve guides and Stellite exhaust valves are optional, depending on how much you intend to drive the car.

Like original Austin cylinder heads, the Nissan heads all look similar on the outside but had various internal porting and a few different sizes of valves over time. The Japanese casting numbers are likely different, and the heads may have been rebuilt with various modifications over time. So you never know what you have until you pull the head to check valve sizes and porting configuration. If you have MGA type dual carburetors you are probably "in the ballpark", but it is possible to have undersize valves that can cut into performance considerably (like the Nash Metropolitan head). If you can get a mostly stock MGA to do 0 to 60 in 1/4 mile you're doing okay for a stock engine. My large valve 1500 with stock cam could do 62 in the 1/4 mile, and I have a house full of autocross trophies to go with it. Vintage sports cars are not all about power, so if you are not building a concours car, don't worry too much about a substitute cylinder head. Photos below are from an Australian made B-series head with different combustion chamber shape.