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There was a series of different engine block blues used to denote the compression ratio on the 3.8L series available for Mks VII, VIIM, VIII, and IX. Unless my memories playing tricks AFAICR

Did this blue colour scheming also apply to Daimler Sovereign 4.2L? I believe my 4.2L was a mid-80s version, but have no idea what its compression ratio is (was) The engine number is 7A35393-8 (8 = 8:1?). Heritage could only confirm that it was an 80's Sovereign

Thanks to anyone with clearer memory and or some lists to refer to
(x-posted to wherever the Daimler Sov lot hang out)

Was it just the cylinder head that was painted blue etc?

Could've been -- but my memory's not what it was
Here's a pic of what's on the block. But could this be a number for the cylinder head?

[URL=http://s1361.photobucket.com/user/ ... jpeg[/img][/url]

Richard SEL,
I think my brain is becoming addled too . As far as I can remember all blocks were black, cylinder heads had colours, except the early ones with plain aluminium , then green then blue, also red ( XK 120 ) and gold for E type and possibly Mk 10. These colours denoted head design changes valve angles etc. Compression ratio's were identified by a suffix number i.e. -7 (overseas I think) , -8 and -9 on the cylinder head. This number was/is located down the Vee just in front of the front spark plug.

There, how did I do, Is this a question for Master Mind ?

That's as I remember it for the 3.8L having a suffix for the compression ratio
But was trying to find out (hence my X-post in the XJ forum) whether that system also applied to their 4.2L lumps too?
And whether they also had a colour system for their cylinder heads

Here's a pic of what my 4.2L looks like now...
[URL=http://s1361.photobucket.com/user/ ... .jpg[/img][/url]

Since the lump is coming out, might as well get the colour correct before it goes back

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As that's where the XJ6/Daimler Sov lot hang out