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MG MGB Technical - Gold seal engine information

Hi, I recently acquired my first MGB (1970 Chrome). The P*O did not keep any history so I am trying to sort out whats fitted where. My main difficulty is the engine. I have managed to get to it being a 'Gold Seal' (no sign of gold paint though) as it has a plate number of:
48G 755 EP nnnn I have found a reference that states the 'E' is for Exchange but no where can I find any reference to the 'P' or the numbers (Which I guess indicate a 'rebuild' period/date). Also http://www.mgb-stuff.org.uk/enginetext.htm#goldseal shows it to be 'High compression' but Haynes does not show different comp ratios for the equivalent model (GD/GG). Does this make any difference on maintenance etc. Any thoughts welcome.
Thanks in advance
Bernie
B Anderson

As 755 isn't listed by Clausager for the MGB it can only be either incorrect (doubtful) or more likely an engine for another model such as the Marina. As the MGB engine numbers seem to be consecutive, with 737 the highest before the change to BHM numbers, it would seem to date to around 1974/75.

My Haynes has the following statement or similar in italics for 18GB and later engines: "The specifications above apply except where modified/superceded or added to by that below.", and the 18G and GA specifications include low and high compression engines. As far as routine maintenance goes only ignition timing is affected by compression ratio. You can get an idea of the compression ratio by doing a compression test, but obviously a high compression engine in poor condition may well give readings more appropriate to a low compression engine.
PaulH Solihull

Seems to me there were a few people re-building 1800, and no doubt other, engines, then spraying them gold. I've just dismantled a so called gold seal MGB engine. +20thou overbore with a 1622cc cylinder head!!! I have the invoice passed on from the PO. Gold Seals were always linered, so I believe, and presumably had the correct head as well. The up side is the head is good and I've ported it fitted hardened seats, AND the crank is steel!
Allan Reeling

Actually page 69 of clausager lists 48G 755 as a gd/gg replacement. I just wondered what the letter P might mean in the full plate number of:
48G 755 EP 15963
B Anderson

An early Sprite/Midget/B/C/V8 centre parts book lists 5 bearing 18GB onwards - 48G 755E as 'MGB alternator spec up to 18v engine 1972 exchange engine' and 48G 733E as 18V on.
BHM 1111E Rubber bumper cars on.

R.
richard boobier

Thanks all,
I guess the reality is that these things are lost in the midst of time :) At least I know its an MGB engine and not a lower quality Marina 'lump'. I will have to wait till the rocker cover is off to check the head type but there no hurry.
B Anderson

This thread was discussed between 21/11/2011 and 23/11/2011

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