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MG MGB Technical - MGB/Nissan Head

I ran up on a head like this in a machine shop some years back and commented on it on this BBS. Most thought I was nuts and a few even told me so, but here is one for sale. Look at the casting letters.

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&category=42606&item=2438991414

David
David

I'm not one of the historians on this board, but I do know that Datsun manufactured the 1600/2000 Fairlady - pretty much a licensed copy of the MGB. It's a huge investment to design and engineer something from the ground up. So it's not beyond imagining that Datsun/Nissan would modify a head they already owned to use on a later engine.

But as an aside, that elbow hanging off the head suggests a heater valve solution. I don't have a lathe to turn down an existing heater valve base. But I could drill into the heater valve opening and tap in a pipe fitting. Then connect a hose to the fitting and use an in-line heater valve.

I wonder if there's enough metal there to drill and tap a big enough hole without ruining something?
Matt Kulka

No need to drill and tap - the Austin / Morris Marina and other B engined cars had a simple elbow bolted onto the head.

Easily enough made up from a flat piece of steel and either a straight pipe or an elbow welded in.
Chris at Octarine Services

That's interesting. I wonder how it flows compared to the 'B head and what size intake valves it uses. My guess is that it comes with the heater valve elbow. Used to see a lot of those Datsuns racing in SCCA production classes (I don't remember which class, was it E?).
Marvin Deupree

The Datsun Roadster came out BEFORE the MGB and it was suggested in a BRITISH magazine recently that perhaps the MGB was influenced by the Datsun. The only British licensed parts are the Dunlop brakes (also licensed by Alfa) and the SU HS carbs - Datsun did their homework and redesigned significant features and IMHO are much better machined than the SUs as used on Bs. That being said the Roadster head will not fit an MGB although it was told to me that MGB racers are using Roadster cams. The Datsun head which may be adaptable to a B engine is probably from the 'A' series engines. The Roadster engines don't have siamesed intakes and the 2000 engine was an OHC head with huge ports and a forged fully counter-weighted crank (which I used to stroke my 1600). The rods are beefier than big block Chevies and the machine shop who balanced my engine told me he couldn't believe how well balanced the reciprocating parts were as compared to American and British engines. Basically all OHV heads are similar but the coolant and oil passages and other important items are far different. The Datsun Roadster has a full frame under it using tube shocks all around and ball joints rather than trunnions in the front which is a big improvement although the worm and lever steering box is not as good as the MGBs rack and pinion. I've owned my 66 Datsun Roadster since 79 and I own a 67 B. Oh, I don't have to fuss with the pedal box to change either my brake MC or clutch MC as I had to do on my B.
Mike MaGee

I should have mentioned that the head that I saw many moons ago was supposedly from a Datsun forklift.
David
David

How very odd.

That is clearly a B head with some detail differences - the rocker cover is held on with four screws round the edge rather than 2 studs at the top; the rocker pedestal lands are a different shape; the port face is further from the bore centres; the heater valve area is different (and the metal where the gasket isn't has been cut back a bit), and the corners are sharper on the thermostat area.

You can tell that it's not an A series derivative as it has 11 head stud holes - the A only has 9. This is clearly not a magic source of performance B heads though - look at the size of those intake ports!

I shall have to ask my handy local rover history expert about this bit of licencing.

ttfn,
--
Olly
Oliver Stephenson

edit... the comment about the metal around the gasket was meant to apply to the comment about the port face being further outboard. Wasn't paying attention, sorry...

--
Olly
Oliver Stephenson

Mr. MaGee,

The "B-Series" engines were around long before the Datsun 1600 plans were ever put to paper. Think not, just have a look under the bonnet of the MGA. As for Syd Enever and Don Hayter's team getting styling "Q's" from Datsun, I would think not. While they may have been aware of the Datsun, the French and Italians most likely played a bigger part with styling. David Knowels has all of this well documented in his book, "M.G. The Untold Story".

Perhaps I'm wrong on this point, but as well built as they may have been I just don't see many Datsun 1600's about? Further, maintenance issues that you point out aside, I found them bit too boxy for my taste even when they were new.

Regards,

L.C. '74 B/GT
Larry C.

interesting.....
I took apart a 75 with an engine (block) from a 72 and until I lifted the rocker cover I did not know that it had a nissan cyl head. I was wondering what to do with it? I think I might send a message to the seller and inquire as to why he believes, other than the shape it looks close, that it would work on a B
andy heston

I saw, years ago there was a datsun 1200 p.u. that had a motor just like the B but smaller bore & stroke. If you saw a B & datsun motor apart on a bench 10 ft. away, you could only see the smaller bore diff.
Glenn Towery

The B also started life as a 1200cc unit... does anyone know what the stroke was? Surely they didn't keep the stroke the same between 1200 and 1800...

ttfn,
--
Olly
Oliver Stephenson

Oliver
The A series did have an 11 stud head, although generally on the Cooper S, and teh 1300 range of GT and MG.

As I understand it, Datsun produced the A40 under licence from BMC in the 50's, and consequently much of their technology was copied. In South Africa, the 1200/1400 Datsun engine used int he cars and pick-up trucks had an A cast into the block which I was told stood for Austin Copyright. In fact the Datsun engine was just identical to the A & B series, and was used as an upgrade in Morric Minors, midgets and Spitfires etc.
FWIW
Martin

I do beg your pardon, I'd forgotten all about the different blocks and heads used on the cooper S. I was taking my marks from a friend's 1275 midget and my mum's non-cooper mini. Sorry :o)

--
Olly
Oliver Stephenson

I should have been clearer. I mentionned an 'A' series engine and I meant a Datsun 'A' series head - that's what that casting mark is for. The forklift head is the same as a Roadster head but the ports are far smaller, it's made of cast iron and the head is super heavy duty. I had one and heaved it as the ports were just too small and restrictive. For whatever reason, although forklift engine parts are interchageable with many Roadster parts, the forklift parts are half-price. FWIW, I have a forklift block in my car as it has 5 mains and is better constructed than the Roadster block. There is no arguement that Datsun's first cars were licensed Austin cars and that the Japs were heavily influenced by the British cars. However by the time the Roadster was built they were going their own way. I think it was a strange convergence that the B and Roadster looked so similar. I remember sneaking my Roadster into a British show many years ago and no one questionned it. In my opinion the B was influenced by the Italian and French cars and not the Datsun but I only repeated what I read. Too bad MG and Datsun didn't copy the convertible top mechanisms too!

I can't wait to fully restore my B correctly and then compare the cars. As it is my B needs work while my Roadster is fully restored although it's an older restoration.

Didn't mean to raise any flames but I had to be the devil's advocate and excite some people.
Mike MaGee

Yikes. Mike, thank you for correcting me about the Datsun NOT being an MGB stepsister. I haven't seen one since my youth, but sure would like to. I remember mentally putting them on my "gotta get one of those someday" list about the time I got my driver's license.

And to the rest, thanks for all of your additions to this thread. I really enjoy the potpourri of arcane knowledge.

Carry on, please!
Matt Kulka

Mike: do you really mean to suggest the MGB was based on the Datsun or is that a typo in your first sentence?The Datsun 1600 had no influence on MGB design whatsoever. The B styling was based on the MG EX181 record car and not on the Datsun (never heard of this assertion before) or the Renault Floride as some have claimed (notably Renault themselves). I see no styling resemblence between the 1600 and the B at all. The Datsun more resembles a TR4-narrower, longer, and more angular than a B and on a separate ladder chassis rather than a B type monocoque but I doubt any big influence either way.

It is much easier to observe B series engine influence on the Datsun 1600. In their Roadster advertising Datsun referred to their induction as "SU type twin carb" with no mention of the name Hitachi though they most certainly were. The big divergence came in 1967 with the 2 litre engine which was a stroked version of the 1600 with a wonderful alloy overhead cam cylinder head. This head had wedge combustion chambers and came from the factory with smooth contoured intake ports. It was mated to a 5-speed tranny and boasted 135 HP @6000 RPM stock. Redline was an astounding 7000 RPM made possible by those heavy duty rods and crankshaft Mike mentions. The car did 0-60 in 9 seconds and topped out over 120 mph. Install a fast road cam and upgraded carbs and you're on the sweet side of 150HP. Exciting performance in 1968 for a sports car that cost $100 more than a B and $300 less than a TR250.

All this brings up the question of why couldn't BMC have developed the B series engine along the same lines in the mid -late '60's instead of taking so long to get the O series into production?

I knew a guy in the mid 70's with a Datsun 2000 and remember the seamless strong acceleration up to 100 mph (in third gear!)and cruising at 120. I'm devoted to my Bs and much prefer the styling but I must say that as a young man in the late '60's I know I would have gone with the great Datsun performance after test driving both cars.
Terry

This thread was discussed between 23/10/2003 and 25/10/2003

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