Excellent, excellent advice, Les. From my post last night, it was only $28
to install pistons on rods.
Question on honing - shouldn't the new pistons have come with info on the
honing pattern? They're AE pistons. The machinist says he doesn't need it
- his machine "figures it out automatically" based on geometry. This is
new to me. Any experience with this out here? I'm calling the distributor
anyway.
-------------------------------------------------------------------
> From: Les Myer <lmyer@sprynet.com>
> To: Matt Liggett <mliggett-receive-spridgets@elise.kiva.net>
> Cc: spridgets@autox.team.net
> Subject: Re: 1275cc bore?
> Date: Friday, April 03, 1998 8:06 PM
>
> The machinist will have to install the pistons on the rods
> >
> >The wrist pins are an interference fit in the rods and fit close in the
> >pistons. Correct?
>
> on a 1275, yes.
> >
> >What tools will the machinist use to do this?
>
> a press and a special piston fixture is usually used - this is called
> pressing the piston pins out and in.
> >
> >I have been told it is doable by heating the pistons and rods to about
> >450degF and chilling the wrist pins in the freezer overnight.
> >
> Could work - I have never seen published instructions on doing this.
Plus
> the pins need to be put the small rod end to a certain depth. Sounds
like
> a pain to me. What if the first try doesn't work and the pin doesn't go
in
> all the way before it warms up and catches - then what?
>
> >> (which will probably need resized on the big end anyways)
> >
> >What does it mean to have the big ends resized?
>
> The rod bearing bores are re-sized to ensure perfect roundness and size
as
> well as the angle to the piston pin (if the angle is very bad, the rod is
> considered "bent" and is discarded. This is done by machining a small
> amount of material off the rod cap mating surface, making the bores ever
so
> slightly egg-shaped and a little smaller. Then the hole is restored to
> specifications with a hone to sub-thousandths accuracy (remember oil
> clearance typically runs 0.001 to 0.002.) This is also basically how
line
> boring is performed, only on the main bearing seats.
> >
> >> When going back together, remember the longer rod-cap boss on rods 1
> >> and 3 goes to the rear - on 2 and 4, the long boss goes to the front.
> >
> >Thanks.
> >
> >> If the piston has a dot or a mark, this goes to the front (otherwise
> >> they are probably omnidirectional pistons). If this is your first
> >> time, it might be best to have an experienced friend show you how to
> >> orient the rings (yes, you need a special tool to get them on the
> >> pistons without damaging them or the pistons), compress them, install
> >> the crank/pistons/bearings, and how to plastiguage clearances.
> >
> >I plan to get some guidance, but all of my car friends live a few
hundred
> >miles away, so the best guidance I'll get is by telephone or e-mail.
> >
> >> Not meaning to scare you, just trying to save some heartache and
> >> frustration as well as make sure it is done right.
> >
> >I appreciate it. This is the sort of guidance I'm looking for. But, I
> >am on a budget and I am determined to understand every part of the
> >process, even if I farm it out to a machinist. I also intend to do as
> >much as I can myself. Guess I've been reading a little too much Bob
> >Hoover, eh? (See http://www.type2.com/sermons/).
> >--
> > Matt Liggett
> > '60 Mini, '70 Midget, '89 SAAB 900t SPG
> >
>
> Next, someone will tell you that you don't need a ring expander to get
the
> rings on the pistons. True, you don't if you don't mind scratching your
> new pistons with the ring gap ends and improperly stressing the rings.
> What can I say, I'm pretty anal when it comes to engine building.
>
> Good luck, have fun -
>
> Les
>
>
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