Home  |  Forums  |  914 Info  |  Blogs
 
914World.com - The fastest growing online 914 community!
 
Porsche, and the Porsche crest are registered trademarks of Dr. Ing. h.c. F. Porsche AG. This site is not affiliated with Porsche in any way.
Its only purpose is to provide an online forum for car enthusiasts. All other trademarks are property of their respective owners.
 

Welcome Guest ( Log In | Register )

2 Pages V  1 2 >  
 Reply to this topicStart new topic
> Cracked piston skirt for a big bore kit: machine or replace?
porkchopexpress
post Apr 2 2014, 06:12 PM
Post #1


Newbie
*

Group: Members
Posts: 39
Joined: 18-August 12
From: Tucson, AZ
Member No.: 14,821
Region Association: Southwest Region
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!
(IMG:style_emoticons/default/beerchug.gif)
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
Dr Evil
post Apr 2 2014, 06:15 PM
Post #2


Send me your transmission!
***************

Group: Members
Posts: 23,032
Joined: 21-November 03
From: Loveland, OH 45140
Member No.: 1,372
Region Association: MidAtlantic Region
Toss it and get another.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
r_towle
post Apr 2 2014, 06:17 PM
Post #3


Custom Member
***************

Group: Members
Posts: 24,646
Joined: 9-January 03
From: Taxachusetts
Member No.: 124
Region Association: North East States
A perfect situation where JB Weld might come in useful.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
yeahmag
post Apr 2 2014, 06:33 PM
Post #4


Advanced Member
****

Group: Members
Posts: 2,442
Joined: 18-April 05
From: Pasadena, CA
Member No.: 3,946
Region Association: Southern California
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).
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
messix
post Apr 2 2014, 06:37 PM
Post #5


AKA "CLUTCH KILLER"!
*****

Group: Members
Posts: 6,995
Joined: 14-April 05
From: between shit kickers and pinky lifters/ puget sound wa.north of Seattle south of Canada
Member No.: 3,931
Region Association: Pacific Northwest
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.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
stugray
post Apr 2 2014, 06:47 PM
Post #6


Advanced Member
****

Group: Members
Posts: 3,825
Joined: 17-September 09
From: Longmont, CO
Member No.: 10,819
Region Association: None
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.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
VaccaRabite
post Apr 2 2014, 06:51 PM
Post #7


En Garde!
**********

Group: Admin
Posts: 13,593
Joined: 15-December 03
From: Dallastown, PA
Member No.: 1,435
Region Association: MidAtlantic Region
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
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
wndsnd
post Apr 2 2014, 07:14 PM
Post #8


You wanted a horse, but got a goat. Nobody wants a goat....
****

Group: Members
Posts: 2,861
Joined: 12-February 12
From: North Shore, MA
Member No.: 14,124
Region Association: North East States
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?
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
Jake Raby
post Apr 2 2014, 07:21 PM
Post #9


Engine Surgeon
*****

Group: Members
Posts: 9,398
Joined: 31-August 03
From: Lost
Member No.: 1,095
Region Association: South East States
I thought this was an April fool's joke.. Seriously?
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
Johny Blackstain
post Apr 2 2014, 07:26 PM
Post #10


Walnut Elite Stratocaster player
****

Group: Members
Posts: 3,434
Joined: 5-December 06
From: The Shenandoah River
Member No.: 7,318
Region Association: MidAtlantic Region
I'm gonna go out on limb here & be politically incorrect & say screw the paperweight, make it an ashtray.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
Java2570
post Apr 2 2014, 07:29 PM
Post #11


Senior Member
***

Group: Members
Posts: 649
Joined: 7-May 11
From: Fishers, IN
Member No.: 13,035
Region Association: Upper MidWest
or a cupholder!
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
cary
post Apr 2 2014, 07:31 PM
Post #12


Advanced Member
****

Group: Members
Posts: 3,900
Joined: 26-January 04
From: Sherwood Oregon
Member No.: 1,608
Region Association: Pacific Northwest
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 ......................
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
wndsnd
post Apr 2 2014, 07:37 PM
Post #13


You wanted a horse, but got a goat. Nobody wants a goat....
****

Group: Members
Posts: 2,861
Joined: 12-February 12
From: North Shore, MA
Member No.: 14,124
Region Association: North East States
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....
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
timothy_nd28
post Apr 2 2014, 08:26 PM
Post #14


Advanced Member
****

Group: Members
Posts: 2,299
Joined: 25-September 07
From: IN
Member No.: 8,154
Region Association: Upper MidWest
Maybe if I was stranded on a deserted island, I'd consider the glue (IMG:style_emoticons/default/blink.gif)
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
Allan
post Apr 2 2014, 08:41 PM
Post #15


Teenerless Weenie
*****

Group: Members
Posts: 8,373
Joined: 5-July 04
From: Western Mesopotamia
Member No.: 2,304
Region Association: Southern California
Butt plug... (IMG:style_emoticons/default/KMA.gif)
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
0396
post Apr 2 2014, 09:14 PM
Post #16


Advanced Member
****

Group: Members
Posts: 2,046
Joined: 13-October 03
From: L.A. Calif
Member No.: 1,245
Region Association: Southern California
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)
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
porkchopexpress
post Apr 2 2014, 10:09 PM
Post #17


Newbie
*

Group: Members
Posts: 39
Joined: 18-August 12
From: Tucson, AZ
Member No.: 14,821
Region Association: Southwest Region
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.


User is offlineProfile CardPM
Go to the top of the page
+Quote Post
Mike Bellis
post Apr 2 2014, 10:22 PM
Post #18


Resident Electrician
*****

Group: Members
Posts: 8,346
Joined: 22-June 09
From: Midlothian TX
Member No.: 10,496
Region Association: None
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)
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
Valy
post Apr 2 2014, 10:30 PM
Post #19


Senior Member
***

Group: Members
Posts: 1,677
Joined: 6-April 10
From: Sunnyvale, CA
Member No.: 11,573
Region Association: Northern California
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.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
cary
post Apr 2 2014, 10:53 PM
Post #20


Advanced Member
****

Group: Members
Posts: 3,900
Joined: 26-January 04
From: Sherwood Oregon
Member No.: 1,608
Region Association: Pacific Northwest
http://www.europeanmotorworks.com/vw/type-...-cylinders.html
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
« Next Oldest · 914World Garage · Next Newest »
 

2 Pages V  1 2 >
Reply to this topicStart new topic
1 User(s) are reading this topic (1 Guests and 0 Anonymous Users)
0 Members:

 

Display Mode: Standard · Switch to: Linear+ · Switch to: Outline

Track this topic · Email this topic · Print this topic · Subscribe to this forum

- Lo-Fi Version Time is now: 2nd December 2024 - 02:10 PM
Invision Power Board v9.1.4 © 2024  IPS, Inc.
All rights reserved 914World.com © since 2002
914World.com is the fastest growing online 914 community!
We have it all, classifieds, events, forums, vendors, parts, autocross, racing, technical articles, events calendar, newsletter, restoration, gallery, archives, history and more for your Porsche 914 ...