About to embark on replacing my TR4 head for the second time now
(due to a crack in the first replacement). I noticed that the second
head has a combustion chamber different than the original.
The original head places the valves in a chamber with an outside
perimeter that defines an area about 2/3 the area of the cylinder
perimeter. The remaining 1/3 area is flat, flush with the bottom of
the head.
The new head has the same chamber, but the boundary between the
chamber and the flat area is beveled, not 90 degrees. This, I
assume, results in greater volume/less compression, as has been
talked about in recent mailings.
I had no intention of changing the compression ratio (all I want is
to get the %&$^#* car running!). Should I be concerned about this
bevel? How much will it affect the car's running? Is this perhaps a
later model head?
One pleasant side affect of doing this twice is that I got to use
the rope trick to loosen the head! Not only fun but effective!
Thanks,
---------------
Charlie Farwell
1962 TR4 #CT3852L
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