Pistons got mixed up
Jay S
pistons/rods had no markings on them showing what cylinder they were from.
So, I lined them up on my work bench in the correct order and told myself
I'd mark them later.
I left for work and my dad decided he'd clean the pistons for me while I was
gone. He didn't realize they weren't marked and didn't know I had arranged
them in order. Now they're all mixed up.
He's a helpful bugger isn't he?
Of course I don't have a clue as to which piston came out of which cylinder.
What do I do now? I've always been told to put the piston back in the same
hole it came out of.
The crank was cut down 10/10 under. The cylinders were deglazed/finish
honed.
I've arranged the pistons so all the notches face forward, but what about
the big ends of the rods?
Is there a way to tell which way the rods face on the journals?
At least this taught me to mark each piston as it comes out. I swear I'm
gonna do that everytime form now on!
Any help???
Jay S
David J and Lynne J Shepherd
one, look at the big end of the rod you will see a more significant chamfer
on the rod big end bore one side is more obvious than the other, the larger
chamfer faces against the crank journal, not against each rod. This way you
can arrange the rods in the proper positions on the crank, as for which
cylinders on each side this is another problem, if you are using new rings
and bearings I wouldn't worry about it.
"Jay S" <IREALLYHATES...@shaw.caSPAMSUCKS> wrote in message
news:QG6U9.18096$Yo4.1...@news1.calgary.shaw.ca...
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Jay S
journal not towards each other.
Here's the problem (I'll try and draw it out, hope it works)
I've got 6 rods that the caps are chamfered this way:
_
/ l
I've got 2 that face this way
_
l \
the best I can do with this set up is 2 pairs that line up like this (which
is how I think they all should be.)
_ _
/ l l \
and 2 pairs that line up like this (both chamfers facing same direction)
_ _
/ l / l
The rods are installed on the pistons, so it's not a matter of flipping 2
rods around, unless I can press out the piston pins , flip the rods over,
and press them back in. Not likely unless there's an easy way to do it
without a press.
This just doesn't seem right to me. There is no way to get the rods facing
in the right direction for all the cylinders.
Jay S
"David J and Lynne J Shepherd" <djsl...@capital.net> wrote in message
news:3e219...@corp.newsgroups.com...
BACKNCARDR
>From: "Jay S" IREALLYHATES...@shaw.caSPAMSUCKS
>Date: 1/12/03 12:42 PM Pacific Standard Time
>Message-id: <0rkU9.21538$sV3.1...@news3.calgary.shaw.ca>
>
>That's what I was taught, the chamfered ends of the rod go toward the crank
>journal not towards each other.
>Here's the problem (I'll try and draw it out, hope it works)
>
>I've got 6 rods that the caps are chamfered this way:
> _
>/ l
>
>I've got 2 that face this way
>_
>l \
>
>the best I can do with this set up is 2 pairs that line up like this (which
>is how I think they all should be.)
> _ _
>/ l l \
>
>and 2 pairs that line up like this (both chamfers facing same direction)
> _ _
>/ l / l
>
>
>The rods are installed on the pistons, so it's not a matter of flipping 2
>rods around, unless I can press out the piston pins , flip the rods over,
>and press them back in. Not likely unless there's an easy way to do it
>without a press.
>
>This just doesn't seem right to me. There is no way to get the rods facing
>in the right direction for all the cylinders.
>
>Jay S
Shezam, looks like someone already replaced the pistons and didn't index the
rods worth a shit. If this engine was already running like this be4 you tore it
down-it is a moot point.
Respectifully submitted,
Loren Knighton
Woodland, CA.
Under the hood since 1964
Member TRNI IATN
Dave Baker
principles. Having to reassemble an engine without the aid of a manual that
someone else has already stripped isn't uncommon in my line of work but some
basic engineering principles usually sort it out.
1) Gudgeon pin offset. Pistons usually have the pin slightly offset to one
side. Only by 1mm or so but enough to measure. If this offset is present then
all the pistons should have it facing the same way. Normally the piston is
fitted such that the pin is closest to the thrust side of the engine. That's
the left hand side of each bank as you look at the engine from the front i.e
such that it rotates clockwise as you look at it.
V8s don't always use an offset pin. If it is central and there are no valve
cutouts then the piston can be fitted either way round.
2) Bearing tangs on the rods. Both tangs for the upper and lower shell are
usually on the same side of the rod. On a four cylinder all rods should be
fitted such that the tangs are on the same side of the engine unless a crank in
the rod indicates otherwise (see 7 below). Usually this is the same side as the
tangs for the main bearing shells too.
3) Oil squirt holes in the rods. If there is a small drilling from the big end
shell to the outside of the rod to squirt oil up under the piston then these
holes would normally all go on the same side of the engine.
4) Piston cutouts. Not always present but an obvious guide to piston alignment
if the inlet cutouts are larger than the exhaust ones.
5) Pip marks or casting marks on the rods. Again these would be expected to
point the same way.
6) Arrows on the piston crown or pip marks on the flats by the pin. Usually
meant to point to the crank pulley end of the engine except for French engines
(Peugeot, Citreon etc) where both the cylinder numbering and point marks is
done from the flywheel end. If I had a quid for every French engine that some
semi skilled twerp has assembled thinking the crank pulley end is the front I'd
be a richer man than I am.
7) Crank or offset between the big and small end of the rods. Usually only
found on V engines where two rods share a journal. Leyland A series engines
have it also though. These should usually NOT all point the same way but will
be relative to any corresponding offset between each crank journal and the
centre of that bore.
8) Chamfers on the sides of the big end of the rod. Small and large chamfers
usually mean the rod is oriented one way round relative to the adjacent crank
web and/or the adjacent rod if two rods share a journal.
If the bores have been honed/rings replaced then it makes no difference which
piston goes back in which bore other than perhaps grading piston sizes and
trying to match them nicely to bore sizes.
Dave Baker - Puma Race Engines (www.pumaracing.co.uk)
Duncan Wood
"BACKNCARDR" <backn...@aol.comno1spam> wrote in message
news:20030112171714...@mb-mw.aol.com...
You might want to wander down to your local engine shop & ask them. They'll
probably be amused but helpful
Steve
fact they're one of my favorite GM designs along with Buick) but I do
have a suggestion. I see that you found the piston notches and got that
taken care of... now look at the big-ends of the rods (with the caps
installed). Does one side have an oil squirt hole where the cap and rod
meet? If so, the squirt hole should face *up* and toward the opposite
cylinder bank when the rod/cap is installed on the crank. The squirt
hole sprays the cylinder across from the one that the rod is attached
to, so that the rod of each cylinder oils the cylindr walls/rings of its
partner on the other side of the engine.
At least thats how Mopar v8s work.
Good luck!
Steve
> 3) Oil squirt holes in the rods. If there is a small drilling from the big end
> shell to the outside of the rod to squirt oil up under the piston then these
> holes would normally all go on the same side of the engine.
>
Whoah, whoah whoah! Not on v8s. The squirt holes alternate so that the
rods of the left bank squirt the right bank cylinder walls and
vice-versa. See my previous reply.
Jay S
"BACKNCARDR" <backn...@aol.comno1spam> wrote in message
>
> Shezam, looks like someone already replaced the pistons and didn't index
the
> rods worth a shit. If this engine was already running like this be4 you
tore it
> down-it is a moot point.
>
>
>
> Respectifully submitted,
>
> Loren Knighton
> Woodland, CA.
>
> Under the hood since 1964
> Member TRNI IATN
>
>
I'm starting to think the same thing.
I bought the engine used , already pulled out of the car it was in so I
never saw it running.
It didn't look like it was apart anytime recently.
Tomorrow I'm going to buy another Olds 403 and pull the pan and see how the
rods are laid out.
I found another complete engine (sold as a core) for $150.00 . I may use the
piston/rods out of that engine to replace the mixed up assembly I have now.
(Assuming that those pistons/rods check out OK and the bore is the same)
Jay S