Re: Head Dimensions

["JOHN CLAYTON" <john.h.clayton@domain.elided>]

Wendy,

In the absense of a reply from the usual "gang" let me
try and help.  I'm currently reading through all (yes,all)
the SOC magazines selecting articles and other text for
a Technical Reprint book which should be published
in the reasonably near future.

(I agree that if everyone had Internet access it wouldn't
be necessary, but they don't -yet- so it is!)

On the subject of cylinder head thickness I've so far
come across the following:-

In Issue no.13 (December 1980) Tony Hart wrote:-
"It is possible to skim up to 20 thou using a standard
head gasket, and up to 40 thou using a thick head gasket."

In Issue no.32 (October 1982) Tony Hart wrote:-
"The quickest and easiest way to measure the thickness of
cylinder heads is the following rule of thumb method:-
With the inlet valve seated in the head, if the valve is below
the head surface standard head gaskets can be used.
If the valve is proud of the head surface a thick head gasket 
must be used.  If an excessive amount has been skimmed off 
the cylinder head so as to start cutting into the inlet valve seat
material, then the head cannot be used."

He warns against fitting a MK1 head to a MK11 block but says
the reverse is possible.

In Issue no.35 (January 1983) Malcolm Gough related how he
decided to write to BL at Cowley for the definitive measurements.
Armed with their reply he wrote:- "The minimum depth 
measurement from the block face to the bottom of the camshaft 
bore is 4.427in. BL suggest you use a ball bearing to ensure that
the check is carried out from the bottom of the camshaft bore.
Take a reading and subtract the size of the ball bearing.  The
procedure can be carried out at both ends of the bore."
  
Of course it depends what BL mean by "minimum" here.
I would think Tony's rule of thumb method is your best bet.
I seem to recall reading somewhere that 4.5in. was the original
measurement but don't quote me on that.

I hope this helps you.

John Clayton
SOC member 1570.

----------
> From: Wendy Dron <Wendy@domain.elided>
> To: Stag Mailing List (E-mail) <stag@domain.elided>
> Subject: Head Dimensions
> Date: 19 February 1999 09:08
> 
> Good Morning All
> 
> Does anyone out there know the correct thickness for Mk I and MkII heads,
in
> their original unused state.  We've got one of each at the moment, and
have
> just been told that they're beyond planing and are thus knackered, but
we'd
> like to know exactly how knackered!
> 
> Many thanks,
> 
> Wendy
> ____________________________________________________
> Wendy Dron, BA(Hons), PGDip, AITI
> Senior Staff Translator
> 1st Applied Translations Ltd, 2nd Floor
> 39 Ludgate Hill, London EC4M 7JN
> 
>