Hello Larry:
Thanks for the comments.
David F. Darby
Trying to get ahead in the Ozarks.
----------
>
> David Darby wrote:
>
> > ...[snip] ... The engine is a non-original +.030" 1600 with a mkII head.
> Hmmm ... *very* interesting. Commencing with the 1622, high
> compression ( HC - 8.9:1) and low compression (LC - 8.3:1) versions
> were fitted. 'Flat-tops' are standard on the HC 1622. A 1588 overbored
> +.032" equates to the 1622 standard bore of 3". Perhaps ... your 1588
> was overbored to 3" and fitted with a set of HC 1622 pistons and rods.
That's what I first thought until I removed the carbon buildup. The pistons
are
clearly stamped "+.030", Made in England," but no mfr name. I'm familiar
with
the piston configurations and these are definitely flat.
> > ... [snip] ... and someone has ported and polished the head extensively
> > if not expensively. [snip] ... Now I
> > have it back and am concerned that it may be excessively milled by
> > the cumulative amount of machining it has had over the years. ...
[snip]...
> > I do not have the burette setup to accurately measure the combustion
> > chambers, but I may have to devise one in order to answer my questions.
> > Does anyone know the factory dimensions for head height? I am probably
> > milled at least .095" (2.4mm) from stock.
>
> The rule of thumb is that removal of .010" equates to a 1cc reduction in
> the combustion chamber capacity, but the chambers have been modified
> so your right ... you will have to cc the chambers to determine what ya
have.
> Assuming a 3" bore with 'flat-tops' ... my WAG is that 37.5cc equates to a
> 10:1 CR ... 35.5 is a 10.5:1 CR.
I am jury-rigging a measuring setup now. If it works, I will describe it
later.
> At some point the head becomes thin enough that the exhaust valve will
> foul the block (thats why the 18V has the eyebrow cuts) ... so you may
> want to insure that ya have the minimum lift clearance of .060".
Good point.
> > Is this excessive? Should I consider double-gasketing the head? Will I
> > be able to burn 92 octane fuel?
>
> Seems a bit radical ... did you have problems with pinging/detonation
> prior to the valve work? If not, there are several of us that would love
to
> know the size the combustion chambers. ;^)
A slight ping was sometimes present, pulling a long hill in top gear at
WOT, e.g.
>
> Safety Fast! ... larry.g.unger@lmco.com
> '61 MGA 1600 MkII
|