> Can someone tell me, or refer me to an authoritative source
> on, whether you can bore a 1600cc block out to 1622cc? The
> machinist I'm using, who does the engines for a local LBC
> specialist's garage, says he checked (I don't know where)
> and said the walls are too thin--I have to stay with stock
> bore dimensions. Others on this group, who I trust are
> knowledgeable, have said it can be done.
I'm sure that Bill S. will jump in here as he has first hand
experience.
Tell your machinist that you are within stock bore dimensions
... the Factory Work Shop Manual indicates that oversize
pistons are available in +.010", +.020", +.030", and +.040".
The standard bore for the 1588 is 2.968" ... if you overbore
by +.032" then you have the 1622 standard bore of 3" ... you
could overbore for 1622 +.010" pistons and only be +.002 over
the 1588 +.040" pistons. I don't see the problem ... you could
overbore +.032", fit standard 1622 pistons, and still allow
for an addtional overbore for either the 1588 +.040" pistons
or the 1622 +.010" pistons. In fact you might want to consider
another machinist ...
> I have an 1800 head I'm going to use either way. Of course,
> if I can and do bore it out to 1622 (3"), the problem
> becomes:
> a.) ensuring proper compression ratio with the right piston
> shape/head-shaving--apparently a tricky task, and
The early 'B' 43cc heads are essentially the same as the 1622cc
head ... so, when fitted with the 'flat-top' 1622 pistons you
will have a 8.9:1 CR without any mods. If you fit the head in
conjunction with the 'dished' 1588cc pistons then the head will
need to be shaved to maintain the orginial CR of 8.3:1.
> b.) locating rods at reasonable cost, as the old stock 1600
> rods are too small at the small end for the larger wrist pins.
> Moss has 1622 pistons but no rods. I can't afford custom-made.
Pick up a set of used 1622 rods ... have them checked for length
and balanced.
The other alternative is to fit a set of custom pistons from folks
like Venolia ... this would allow you to fit 'flat-top' pistons
to your 1588 rods. The pistons are actually pretty reasonablly
priced.
> If boring out is posible, is the gain in displacement worth
> the extra trouble (and risk to the block)?
As you can see from above, the gain in displacement isn't that
great ... however, fitting the 1622 pistons and the 43cc head
will provide a significant incease in power due to the increased
CR and improved porting.
> Hope this isn't a dumb question ...
Nope ...
> ... if someone can point me to a reliable book, I'll read it.
> The info isn't in Burgess or the MGA shop manual.
Well ... I think the shop manual gives the info required to
deduce that its possible, but I don't know of a book that
outlines this type of mod for the 1588 engine ... perhaps
Bill S. should publish one ... ;^)
Safety Fast! ... larry.g.unger@lmco.com
'61 MGA 1600 MkII
|