Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 11-04-2016, 10:13   #16
Registered User
 
Sailor647's Avatar

Join Date: Feb 2013
Location: Hailing Port: Portland, Oregon
Boat: Norseman 400
Posts: 197
Re: Rebuild question on Groco K

Quote:
Originally Posted by wsmurdoch View Post
Tell me, what am I changing when I flatten the piston rings? Am I making the ring wider, that is increasing the width of the ring thus making the outside diameter greater and the inside diameter smaller? Or, am I making the piston ring longer so that the gap disappears thus making the piston ring bigger in diameter?

Do you have any pointers or technique? I think a re-rebuild is in my future.
You are changing the OD (outside diameter) of the Delrin rings so they fit tight against the inside of the brass cylinder.

The steps I use:
1. Gently tap one side (the flat surface) of both rings to expand them slightly. And by slightly, I estimated a millimeter, but this measurment will vary with each head. I used a medium weight ball peen hammer with smooth face and placed the ring on a smooth metal dock cleat. I don't recommend using a framing hammer (too heavy) or a hammer with any sort of pattern on the face. Don't place the ring on wood (too soft) or concrete (too rough.)
2. Place both rings on the piston and insert the piston and rings into the cylinder. I used a thin, sharp blade to coax the rings into the cylinder being careful to not cut the rings.
3. Check for fit. Move the piston up and down the cylinder with your fingers. Does the piston slide easily? (Rings are still too small.) Can't move the piston up and down? (Rings are now too large.)
4. Repeat step two until the rings fit really tight, but you can still (just barely) move the piston up and down in the cylinder.
5. Remove the piston and rings and lubricate the rings with marine grease.
6. Reinstall the rings and piston inside the cylinder.

The specs for a newly built head call for .001" of clearance between the OD of the rings and the ID of the cylinder - a really, really tight fit - but most people don't carry a micrometer onboard. And the plastic rings are a challenge to measure accurately since they are flexible.

When we rebuild the head again in 6-12 months, we'll take pictures and post a complete set of color work instructions on the forum.

Let me know if you have any more questions - happy to help. (We are headed into the Sea of Cortez in three days and will be out of internet range for quite some time.)

Good luck!
__________________

__________________
Sailor647 is offline   Reply With Quote
Old 11-04-2016, 10:34   #17
Registered User
 
Sailor647's Avatar

Join Date: Feb 2013
Location: Hailing Port: Portland, Oregon
Boat: Norseman 400
Posts: 197
Re: Rebuild question on Groco K

A couple of pics that may help.

To test the fit of the rings, I inserted the piston upside down so I had something to hold on to.
Attached Thumbnails
Click image for larger version

Name:	IMG_3640.jpg
Views:	57
Size:	403.2 KB
ID:	122481   Click image for larger version

Name:	IMG_3642.jpg
Views:	52
Size:	386.4 KB
ID:	122482  

__________________

__________________
Sailor647 is offline   Reply With Quote
Reply

Tags
rebuild

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Groco vs Conbraco Valves... Christian Van H Plumbing Systems and Fixtures 31 22-09-2014 09:21
Groco Sweettank Amwasp Plumbing Systems and Fixtures 7 21-09-2009 08:30
Seacocks - Perko, Groco, Forespar, Apollo SkiprJohn Plumbing Systems and Fixtures 24 22-02-2009 13:08
Groco Recall AnchorageGuy Plumbing Systems and Fixtures 5 31-12-2007 03:03
Groco HF drh1965 Plumbing Systems and Fixtures 1 05-11-2007 22:24



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 17:28.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.