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> Cracked piston skirt for a big bore kit: machine or replace?
porkchopexpress
post Apr 2 2014, 06:12 PM
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I recently picked up a 73 1.7 (was originally told it was a 1.8.... didn't think to check the engine stamp to verify. (IMG:style_emoticons/default/headbang.gif) but I got it for a song).

I also and looking at picking up a big bore kit (94mm by Kolbenschmidt) for trade. The original plan was they should bolt onto the 1.8 and be a pretty easy setup.

With the 1.7, I understand I will need to have some head work done to accept the larger cylinders and pistons.

Here is my dilemma: one of the pistons has a chipped skirt. The cause of the broken piece is unknown.

Attached Image

Attached Image


I realize it MIGHT work to just use it as is, but as the person who is offering these in trade so rightly stated: " Emotional side of me says I don't like putting an engine together with something I know is not quite perfect"

So I figure my options are to
a) get all the piston skirts machined off to match
b) inquire on the classified section if anyone has a single 94 mm Kolbenschmidt they would be willing to sell (hopefully cheap since its only one!)

Anyone have input on the first option to machine off all the skirts to match?
Thanks as always!
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Dr Evil
post Apr 2 2014, 06:15 PM
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Toss it and get another.
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r_towle
post Apr 2 2014, 06:17 PM
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A perfect situation where JB Weld might come in useful.
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yeahmag
post Apr 2 2014, 06:33 PM
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JB won't hold up in an environment like this. You need to user Crazy Glue or maybe Gorilla Glue if you have lot's of water in the oil (it's activated by water).
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messix
post Apr 2 2014, 06:37 PM
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it's a paper weight!

the weight of the piston is now different to the others and will throw of the balance of the rotating assembly. that is the really big problem !

the other issues would be the stability of the piston would be off also and it would rock in the cylinder enough to gall the walls.

if this guy thinks it would run ok with it.... I question the rest of the parts.
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stugray
post Apr 2 2014, 06:47 PM
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I am pretty sure I have a set with one bad piston.
The wrist pin would not go in on just one.

Let me check.
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VaccaRabite
post Apr 2 2014, 06:51 PM
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Big bore is usually a 96mm piston (or larger), not a 94. Sure about the piston size? Or are you just getting stock 2.0 pistons and the seller is calling them "big bore."

Zach
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wndsnd
post Apr 2 2014, 07:14 PM
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QUOTE(r_towle @ Apr 2 2014, 08:17 PM) *

A perfect situation where JB Weld might come in useful.



Ya think?

Why not just bench grind it flat and then do the other side?
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Jake Raby
post Apr 2 2014, 07:21 PM
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I thought this was an April fool's joke.. Seriously?
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Johny Blackstain
post Apr 2 2014, 07:26 PM
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I'm gonna go out on limb here & be politically incorrect & say screw the paperweight, make it an ashtray.
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Java2570
post Apr 2 2014, 07:29 PM
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or a cupholder!
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cary
post Apr 2 2014, 07:31 PM
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QUOTE(Jake Raby @ Apr 2 2014, 06:21 PM) *

I thought this was an April fool's joke.. Seriously?

You and I are on the same page ......................
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wndsnd
post Apr 2 2014, 07:37 PM
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You wanted a horse, but got a goat. Nobody wants a goat....
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QUOTE(wndsnd @ Apr 2 2014, 09:14 PM) *

QUOTE(r_towle @ Apr 2 2014, 08:17 PM) *

A perfect situation where JB Weld might come in useful.



Ya think?

Why not just bench grind it flat and then do the other side?


Reply to my own reply.

It's called "blueprinting an engine".

I read it in another thread....
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timothy_nd28
post Apr 2 2014, 08:26 PM
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Maybe if I was stranded on a deserted island, I'd consider the glue (IMG:style_emoticons/default/blink.gif)
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Allan
post Apr 2 2014, 08:41 PM
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Butt plug... (IMG:style_emoticons/default/KMA.gif)
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0396
post Apr 2 2014, 09:14 PM
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QUOTE(wndsnd @ Apr 2 2014, 06:37 PM) *

QUOTE(wndsnd @ Apr 2 2014, 09:14 PM) *

QUOTE(r_towle @ Apr 2 2014, 08:17 PM) *

A perfect situation where JB Weld might come in useful.



Ya think?

Why not just bench grind it flat and then do the other side?


Reply to my own reply.

It's called "blueprinting an engine".

I read it in another thread....


Actually, it is blue printing...you will need to reduce the other three and keep it under 1500 rpm...oh just short shift. (IMG:style_emoticons/default/biggrin.gif)
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porkchopexpress
post Apr 2 2014, 10:09 PM
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Seems as though most people didn't read the full post. My bottom line question was can I machine off all the slipper skirts so all the pistons match. If that wasn't clear, then that's on me and my bad. I have seen several new big bore kits that have pistons that do not have those slipper skirts so it seemed like a valid question.

Consensus seems to be, "bad idea"

Additionally, I am doing all of this on a budget. Would love to have the cash to send an engine out to one of the guru's on here and have them do it for me, but for now, that's just not in the budget. And in case you didn't notice the "Newbie" designation, I still have a lot to learn. And I enjoy learning so its great to ask about these things to try to figure out what I can, or am willing, to do myself.

I am all for being sarcastic, and can take and dish with anyone.... just wish some of you might have added something valuable to say along with it. Even if its "no clue"

Next time I will be less likely to ask, which sucks.


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Mike Bellis
post Apr 2 2014, 10:22 PM
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Bad idea.

How many times do you want to rebuild it?

Just install it like it is. It will make a cool slapping sound. People may even think it's a rod knock. But you'll know better, laughing all the way with your self machining pistons and bent crank... (IMG:style_emoticons/default/evilgrin.gif)
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Valy
post Apr 2 2014, 10:30 PM
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To your questions:
$200 will get you a new set of 94mm AA pistons, cylinders and rings.
$230 for a new single piston and cylinder from Mahle (German). I think KS that you have are NLA.
Either choice is better and cheaper than what you try to do.
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cary
post Apr 2 2014, 10:53 PM
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http://www.europeanmotorworks.com/vw/type-...-cylinders.html
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