Pelican Parts
Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help



Go Back   Pelican Parts Forums > Porsche Forums > 911 Engine Rebuilding Forum


Reply
 
LinkBack Thread Tools Rate Thread
Author
Thread Post New Thread    Reply
Registered User
 
Join Date: Nov 2019
Location: Central Connecticut
Posts: 66
machine shop head screw up .. info needed ..

So i brought my 6 original heads off my 76 row turbo motor to be rebuilt at a local northeast machine shop that came highly recommended by some local local pca zone 1 members ..It was supposed be new guides, reseat the valves and a light fly cut to freshen up the top of the heads due to broken studs on #4 .. well something went awry with the light fly cut now all 6 heads have the same groove in them and i am afraid the groves are to deep to be corrected by recutting .. so what are my options . can this be corrected? i ' m hoping the cut missed a spot and its is actually a high spot not a grove but its such a gradual transition i cant tell.
i contacted the machine shop and i have an appointment later today . but i would really appreciate some feedback prior to this appointment. i am posting this not to air dirty dirty laundry but because i would like to speak intelligently when i get to the shop . i understand accidents happen but i have a lot of time and money into this motor and i want the heads fixed correctly. what's the correct course of action if these are groves not high spots ?
i took a picture with black tape to reduce the glare so it's easier to see in the picture.
Thanks in advance
Regards Ned


Last edited by gorskined; 01-03-2020 at 05:20 AM.. Reason: fat fingers
Old 01-03-2020, 04:58 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #1 (permalink)
Registered User
 
Join Date: Nov 2019
Location: Central Connecticut
Posts: 66



Old 01-03-2020, 05:03 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #2 (permalink)
Registered User
 
Join Date: Nov 2019
Location: Central Connecticut
Posts: 66
Old 01-03-2020, 05:06 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #3 (permalink)
abit off center
 
cgarr's Avatar
 
Join Date: Feb 2002
Location: At the Airport Kentwood, MI
Posts: 7,083
Garage
Send a message via Yahoo to cgarr
If they are not stamped with the amount removed then ask them how much was taken off. max is .25mm or you could measure them from the top surface to the cylinder surface stock is 84.5mm
__________________
______________________
Craig
G2Performance
Twinplug, head work, case savers, rockers arms, etc.
Old 01-03-2020, 05:37 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #4 (permalink)
Registered User
 
Join Date: Dec 2014
Location: Syracuse,Ny
Posts: 2,352
Too much holiday eggnog perhaps? That's a shame that someone let those out the door.
Old 01-03-2020, 06:42 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #5 (permalink)
Registered User
 
Join Date: May 2016
Posts: 2,131
Highly recommended ?
Old 01-03-2020, 07:10 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #6 (permalink)
Registered User
 
Join Date: Nov 2019
Location: Central Connecticut
Posts: 66
So i just met with the machine shop
The deepest discrepancy ( gouge ) is .039mm they originally took .050mm off so it can be fixed with room to spare
Craig thanks for the info on the tolerances, my heartburn is slowly starting to subside .

Regards Ned
Old 01-03-2020, 09:10 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #7 (permalink)
Registered User
 
cmcfaul's Avatar
 
Join Date: Feb 2003
Posts: 1,547
Garage
Send a message via AIM to cmcfaul Send a message via Yahoo to cmcfaul Send a message via Skype™ to cmcfaul
What will that do to compression? A ROW motor I believe has about as high a CR as pump gas will allow. Machining that off the heads will increase the CR. May want to think about slightly thicker base gaskets to offset.

Chris
Old 01-03-2020, 10:38 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #8 (permalink)
Under the radar
 
Trackrash's Avatar
 
Join Date: May 2007
Location: Sebastopol, the land of wine and redwoods in The Republic of California.
Posts: 6,167
Garage
Quote:
Originally Posted by gorskined View Post
So i just met with the machine shop
The deepest discrepancy ( gouge ) is .039mm they originally took .050mm off so it can be fixed with room to spare
Craig thanks for the info on the tolerances, my heartburn is slowly starting to subside .

Regards Ned
Are you sure about those measurements? .039mm equals about .001". That would hardly be noticeable.
__________________
Gordon
___________________________________
'71 911 Coupe 3,0L outlawed
#56 PCA Redwood Region, GGR, NASA, Speed SF
Trackrash's Garage :: My Garage
Old 01-03-2020, 12:16 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #9 (permalink)
Registered User
 
Join Date: Nov 2019
Location: Central Connecticut
Posts: 66
Quote:
Originally Posted by cmcfaul View Post
What will that do to compression? A ROW motor I believe has about as high a CR as pump gas will allow. Machining that off the heads will increase the CR. May want to think about slightly thicker base gaskets to offset.

Chris
the 76 turbo row motor is stupid low compression like 6.4 to 1
Old 01-03-2020, 12:21 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #10 (permalink)
Registered User
 
Join Date: Nov 2019
Location: Central Connecticut
Posts: 66
Quote:
Originally Posted by Trackrash View Post
Are you sure about those measurements? .039mm equals about .001". That would hardly be noticeable.
they were all between .0015 and .0017" the owner assured me there was nothing over .002 he was measuring and writing down i didn't have my glasses. what made it noticeable was that it was a clean line not gradual and the black mat tape really showed it ( old trick i learned long ago electrical tape will really make any imperfection pop ).. i guess we will see once i get the final #s back. fingers crossed.

Old 01-03-2020, 12:31 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #11 (permalink)
Reply

Thread Tools
Rate This Thread
Rate This Thread:

 


All times are GMT -8. The time now is 04:22 AM.


 
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2020 Pelican Parts, LLC - Posts may be archived for display on the Pelican Parts Website -    DMCA Registered Agent Contact Page
 

DTO Garage Plus vBulletin Plugins by Drive Thru Online, Inc.