Re: 4 cylinder head question

[Jon Pike <jhpike@xxxxxxx>]

> Can someone who has a head off the engine measure the combustion chamber depth and
> diametre?  The measurement can be either in mm or inches, I can convert into the form I
> require.
Well.. to the best of my limited abilities, and accuracy of a cheap pair 
of calipers...  I went to the head off of the basket case motor I'm 
rebuilding, convienently located on the breakfast nook table, (it's good 
to have a VERY understanding wife!) and measured as follows:

Thickness of head (for reference)             4.405"    111.89 mm

Outer diameter of combustion chamber    3.297"    83.75 mm

What I'm calling the "inner angle diameter" is a narrow surface kind of 
like a valve seat, that extends from flush with the surface of the 
head,  to where it stops being a flat angle and joins the original 
hemisphere.  Measurement is at the beginning of the "hemisphere".

Inner angle diameter                                 3.149"    80.0 mm  
(except #4 which was79.62 mm!)

And here it gets more complex,  there are smaller hemispheres around the 
valve seats, #1 and #4 are large and off center,  #2 and #3 are smaller 
and more evenly centered on the valve seats.  Both types come together 
at the spark plug hole, kind of leaving a angled ridge in the middle.  
Rather than try to figure out something else, I measured down from 
approxamately the center of the chamber, to the highest point of the 
ridge.  Usually this was a few mm from the spark plug hole.  This varied 
a fair amount.

Depth of chamber                #1    31.43 mm
                                          #2    30.96 mm
                                          #3    31.06 mm
                                          #4    30.99 mm

BTW engine is a 2L, 72-74 vintage.

Hopefully that gives you something to play around with.

Jon and Marcia
77 Spider
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