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MG MGB Technical - Engine ID

The cylinder head on my "new" '63 B has the number "565394" cast near the thermostat housing. The head has plugged holes for the later air rail connection.

So, this appears to be a replacement head.

Could this head have been installed on either a 3- or 5-main bearing engine? The ID plate is missing from the block, so I'm starting to wonder what's under the bonnet.

Are there any other clues as to engine type, i.e., distributor code?

Thanks,
Greg
Greg Van Hook

Greg - As far as I know, the heads are all interchangeable over the years. Perhaps someone else has more information on that and how to determine if you have a 3 main or a 5 main block. I believe that there is a build "clock" somewhere on the block, from which you can determine when the block was cast, which may be of some help. Cheers - Dave
David DuBois

If you remove the valve cover, and look at the top of the head, you should see another number cast in relief, which is the casting number of the head. If you post that number here, the members will be able to tell you the original application of the head.

Paul B.
P. Barnes

I am going to start building an "identify your engine" webpage!!!

The easiest way to tell a 3 from a 5 main bearing engine is to count the sump bolts -
the 3 main has 19 bolts, the 5 main has 18 bolts.

565394 is the Patent Number of the design of the head and is cast on the front of the earlier heads and under the rocker shaft on later heads.

The head will have a casting (not part) number under the rocker shaft too - 12H906 for very early heads, 12H1326, 12H2709, 12H4376 are the common UK specs, but you also find 12H2596 - a casting used on the Austin 1800 Landcrab.

US cars used the same castings up to the introduction of anti smog heads in 1969 with the 12H2389, 12H2923 & CAM1106, later also 12H4376 once the UK head was modified with the air injection bosses.

Some castings carry a date "clock" with 3 digits - the top one is the day, the left one is the month and the right one is the year - in the early 70s the month code changed to a letter, so 12, G, 3 would be 12th July 1973
Chris at Octarine Services

I'll check out the cylinder head under the valve cover this weekend.

I'd like to add an ID tag to the engine for appearance-sake. I notice that here in the US, Moss and Victoria British don't sell them. I'm guessing it's illegal to re-number an engine? Is it illegal to remove an engine number?

Greg
Greg Van Hook

There is a guy here in Pennsylvania that makes them for pretty much everyone who does a nice restoration. He has the original tools and stamps. Todd Clarke. His site is here:

http://www.clarkespares.com/carparts.html

No, it is not illegal in PA in change the engine number. I think Todd likes it if you can send along a photo cpoy of the British Motor Heritage Certificate and a copy of your title. That way, he knows that you own the car that you want the plate for, but I've only had chassis plates done by him (where ownership proof would be required), but, I don't think he cares regarding engine plates since they don't determine ownership. Well, ask HIM I suppose!

Paul B.
Bensalem, PA
P. Barnes

Thanks Paul,

I forgot about Clarke Spares. He's real close to me. In the meantime, I talked to the owner who had the car restored several years ago and he has the engine ID tag and will get it to me. Turns out, it's the original block. He took the tag off when he had the block boiled out. The head is "new" because the original cracked.

So, slowly but surely, I'm kind of nailing down the history of the car. Now I'd like to nail down the PO who messed up the wiring!

Greg
Greg Van Hook

This thread was discussed between 24/03/2009 and 27/03/2009

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