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 > 1- Porsche Technical Forums > 911 Engine Rebuilding Forum


Reply
 
LinkBack Thread Tools Rate Thread
Author
Thread Post New Thread    Reply
Registered User
 
stevepaa's Avatar
 
Join Date: Dec 2004
Location: san jose
Posts: 4,980
964 deck height

Putting it all back together. Measured my deck height at 1.20 mm using the crushed solder method. What was it stock and is this good to go? thanks
Old 04-01-2005, 06:42 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #1 (permalink)
Registered User
 
ChrisBennet's Avatar
 
Join Date: Aug 2001
Location: Nashua, NH USA
Posts: 8,082
I looked in my notes. On the 964 motor I did (avg) deck height on #3 was 1.27mm and 1.03mm on #6. This was measured at the edge of the piston.
-Chris
__________________
'80 911 Nogaro blue Phoenix!
'07 BMW 328i Coupe
http://members.rennlist.org/messinwith911s/
Old 04-01-2005, 06:49 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #2 (permalink)
Registered User
 
stevepaa's Avatar
 
Join Date: Dec 2004
Location: san jose
Posts: 4,980
Thanks Chris. This was at edge of piston on number 1. Should I do all of them? And what value is too low?
__________________
steve
old rocket inguneer
Old 04-01-2005, 07:02 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #3 (permalink)
Registered User
 
stevepaa's Avatar
 
Join Date: Dec 2004
Location: san jose
Posts: 4,980
Okay, the solder method is good but not required for a 964. The OD of the piston is greater than the OD of the dome cut into the head. So you can just measure at the flat on the edge of the piston. Both solder and gauge are now giving me 0.76 mm of deck height. My machinist took off about .5 mm when he made all the heads the same total height and flat.

So do I need to get a custom shim to go between the cylinders and case?
__________________
steve
old rocket inguneer
Old 04-02-2005, 10:51 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #4 (permalink)
Registered User
 
350HP930's Avatar
 
Join Date: Jun 2003
Location: St Petersburg, FL
Posts: 3,814
Removing that much material could end up bumping your compression by about a half a point unless you correct most of it with the shims.
Old 04-02-2005, 07:49 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #5 (permalink)
Registered User
 
ChrisBennet's Avatar
 
Join Date: Aug 2001
Location: Nashua, NH USA
Posts: 8,082
Quote:
Originally posted by stevepaa
Thanks Chris. This was at edge of piston on number 1. Should I do all of them? And what value is too low?
I'd measure one cylinder on each bank. I'd shim it back to 35-40 thou (.9mm-1mm). Competition Engineering has custom shims for earlier motors. I don't know if they have them for 3.6 motors.
-Chris
__________________
'80 911 Nogaro blue Phoenix!
'07 BMW 328i Coupe
http://members.rennlist.org/messinwith911s/
Old 04-03-2005, 03:28 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #6 (permalink)
 
Registered User
 
stevepaa's Avatar
 
Join Date: Dec 2004
Location: san jose
Posts: 4,980
A well known shop has indicated that if I do not use a shim, but just assemble, then the increase in compression ratio may trip the engine computer to not run the ignition.

Anyone know anything about this?
__________________
steve
old rocket inguneer
Old 04-06-2005, 01:43 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #7 (permalink)
Registered User
 
350HP930's Avatar
 
Join Date: Jun 2003
Location: St Petersburg, FL
Posts: 3,814
Your knock sensor may kick in more if you have one and the timing will be pulled back accordingly, but thats not the same thing as not running the ignition.
Old 04-06-2005, 04:17 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #8 (permalink)
Registered User
 
stevepaa's Avatar
 
Join Date: Dec 2004
Location: san jose
Posts: 4,980
Thanks, that's what I thought.
__________________
steve
old rocket inguneer
Old 04-06-2005, 04:28 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #9 (permalink)
Registered User
 
ChrisBennet's Avatar
 
Join Date: Aug 2001
Location: Nashua, NH USA
Posts: 8,082
These are the figures for the only 3.6 (964) I've measured:
Left bank: 1.23mm deck height for 10.5:1
Right bank: 1.03mm deck height for 10.7:1

0.75mm deck height is 11.1:1

"350" is right. That's a compression increase 6 points (.6). 10.5:1 is about the limit for twin plugs. I suspect that more compression will cause knock (with street gas) which will cause the computer to retard the spark taking with it that extra horsepower or worse.

In my ignorance, I would be more concerned with the piston hitting the head. When I measured deck height in 4 places on the piston I got 4 different values i.e. some places on the piston are going to be closer than where you crushed the solder. Also, remember that when the engine is running, forces will be trying to fling the piston out towards the head.

Knowing just how small the deck height can be (for this flavor of motor) without wacking the head with a piston is one of those things that separates the "experts" from you and I.

A while back I think Dan Jacobs ("Dan J") indicated to someone that you could raise the true compression to the factory stated compression of 11.3:1. See this thread: 964 engine rebuild 11.3:1 compression
-Chris
__________________
'80 911 Nogaro blue Phoenix!
'07 BMW 328i Coupe
http://members.rennlist.org/messinwith911s/
Old 04-06-2005, 05:02 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #10 (permalink)
Registered User
 
350HP930's Avatar
 
Join Date: Jun 2003
Location: St Petersburg, FL
Posts: 3,814
Quote:
Originally posted by ChrisBennet
"350" is right.
Yup, rule of thumb for the big bore 911 motors is about one compression point per millimeter.
Old 04-06-2005, 05:50 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #11 (permalink)
Registered User
 
stevepaa's Avatar
 
Join Date: Dec 2004
Location: san jose
Posts: 4,980
So any one know the minimum measured deck height so pistons don't hit heads when everything is hot and all parts grow?
__________________
steve
old rocket inguneer
Old 04-07-2005, 07:26 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #12 (permalink)
Registered User
 
350HP930's Avatar
 
Join Date: Jun 2003
Location: St Petersburg, FL
Posts: 3,814
The block will grow faster than the crank and rods so there's no issue with temp expansion.

The problem is stretch from the extreme loads of piston acceleration.

I will leave it to the experts to say exactly what it is but if memory serves me correctly I think wayne's book says you need 0.05" or more of deck height. I think that might be a generous number but I have not had a chance to personally investigate this detail yet.
Old 04-07-2005, 03:22 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #13 (permalink)
Registered User
 
stevepaa's Avatar
 
Join Date: Dec 2004
Location: san jose
Posts: 4,980
My deck height is at .031". I guess I'll ask Woods tomorrow.
__________________
steve
old rocket inguneer
Old 04-07-2005, 09:48 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #14 (permalink)
Registered User
 
Join Date: Jul 2001
Location: Houston, TX USA
Posts: 2,072
Garage
Send a message via Skype™ to KNIGHTRACE
I try to keep these motors at .040 if it helps.
Old 04-09-2005, 11:41 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #15 (permalink)
Registered User
 
Join Date: Jul 2001
Location: Portland Oregon
Posts: 6,898
Quote:
Originally posted by Steve@Rennsport
I'd affirm Bill's suggestion;..........040 is the targeted spec for the majority of engines.

Under certain conditions, some race engines can use less deck height depending on the cam profile and ONLY if the piston to valve clearances are precisely measured,.....
__________________
Steve Weiner
Rennsport Systems
Portland Oregon
(503) 244-0990
porsche@rennsportsystems.com
www.rennsportsystems.com
Old 04-10-2005, 04:17 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #16 (permalink)
Registered User
 
stevepaa's Avatar
 
Join Date: Dec 2004
Location: san jose
Posts: 4,980
So does anyone know of a .010 inch shim for 964 engines that have that green o-ring seal at the base of the cylinder?

The cam profile was standard 964.

I'll study up on valve clearance.
__________________
steve
old rocket inguneer
Old 04-10-2005, 07:45 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #17 (permalink)
Registered User
 
stevepaa's Avatar
 
Join Date: Dec 2004
Location: san jose
Posts: 4,980
Talked to Woods and they suggested a base shim of .019 inch as they believed that .031 was just cutting it a little too close and the pistons might hit at high rpm. So he is making my shims which should bring this back to where I started. I will repeat measurements all around the perimeter to get a base value. Also they suggested DC730 as sealant to use around base of cylinders now with the added shim. So how does a projected deck height of .050 inch sound?
__________________
steve
old rocket inguneer
Old 04-12-2005, 07:35 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #18 (permalink)
Registered User
 
Join Date: Jul 2001
Location: Houston, TX USA
Posts: 2,072
Garage
Send a message via Skype™ to KNIGHTRACE
safe lots of stock motors are at about .060" .040 is my target but on a street motor it would be fine.
Old 04-12-2005, 07:52 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #19 (permalink)
Reply

Thread Tools
Rate This Thread
Rate This Thread:

 


All times are GMT -8. The time now is 09:14 PM.


 
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2018, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2018 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.