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MG MGA - HRG Derrington Heads

I am trying to get a handle on the changes during the production run of these original alloy crossflow heads for the B series BMC motors.

If anyone has one of these, I'd appreciate you sending me the serial number, and whether it is small or large combustion chamber, and small or large (for 1622 and 1798 engines) valves. The serial number is normally stamped on a horizontal surface at the back of the head.

Please note that I am only interested in original HRG heads, not the new replicas.

Bill
Bill Spohn

Bill- My head has the smaller valves of the 1500 & 1600 motors and 33cc chambers. Serial # A 570/361 is stamped on the front of head to the right of thermostat housing. It has 1 3/4 HS SU's on a steel manifold. If you ever come across the original fitting instructions I would like to get a copy please. Thanks Gary
gary starr

That's definitely 570, not 470?

It seems out of sequence, but I'm just starting to get a handle on the dates and numbers. Thanks for the data point.

I have the fitting instructions as well as quite a lot of material and an original poster. One of these days I'll set something up on a site as a reference.
Bill Spohn

Bill- yes it is 570. In the 80's I wrote to V.W. Derrington and recieved a letter from Stuart Derrington. He advised me that my head was the 570th built in March 1961.Also just found my paper work for my head and the chamber size is 35cc.My head has at least once been surface planed and now has a thickness of 3.105 between head surface and valve cover gasket surface. What can I do to get a photo copy of the fitting instructions? Thanks Gary
gary starr

Interseting. I was hoping that either that number or the date was wrong as it puts yours out of order. Number 570 should have been built in 1963.

I wonder if old Alf, the one entrusted with the stamps, was a bit under the weather the day he stamped your head? It could have been in 1 - 63, and he just said "Bugger - oh well, no one will ever care...."

I'll arrange to put up a page with the fitting instructions and will post a note here when it is ready.
Bill Spohn

This thread was discussed between 27/11/2004 and 28/11/2004

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This thread is from the archive. The Live MG MGA BBS is active now.