>> 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.
Hmmm ... could be your 1588 is overbored +.062 and fitted with 1622
+.030 pistons/rods. Is the bore 2.998" or 3.030"?
Took a look at the BMC "MGA 1500 and 1600 Special Tuning" booklet
... as you are probably aware, BMC did offer 'flat-top' pistons for the
1588 (BMC Part No. C-12H-173), but they required the use of the Twin-
Cam rods (BMC Part No.s C-AEH-642 and C-AEH-644).
According to "Tuning BMC Sports Cars", the BMC Special Tuning pistons
rods are no longer available (th book was printed in 1970), but Hepolite did
make a piston with a 3.8cc dish (Hepolite Part No. 14986), in lieu of the
stock 7.75cc dish, and a 'flat-top' piston (Hepolite Part No. 15059) for use
with the stock 1588 rods ... perhaps you have the later.
>>> ... [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.
Anxious to hear your findings ...
>>> 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.
With 92 Octane fuel?
Safety Fast! ... larry.g.unger@lmco.com
'61 MGA 1600 MkII
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