Notices
928 Forum 1978-1995
Sponsored by:
Sponsored by: 928 Specialists

Cam timing effects, 32V

Thread Tools
 
Search this Thread
 
Old 11-18-2011 | 03:09 PM
  #46  
BC's Avatar
BC
Rennlist Member
 
Joined: Dec 2001
Posts: 25,152
Likes: 87
Default

I'm in. I course I said that months ago
Old 11-18-2011 | 03:11 PM
  #47  
Mako 928's Avatar
Mako 928
Burning Brakes
 
Joined: Jul 2007
Posts: 1,075
Likes: 2
From: S.F. Bay Area
Default

Dear Santa Ken,

I have been very good this year. Having just installed the latest version of chips along with the TQrings I passed California smog last week with flying colors. Included will be a copy of the smog readout along with the last version of chips I am sending back to you.
This has made the evil smog lords of California very happy so I now deserve a new toy. The new Porken timing wrench set will be on my list.

P.S. I have left you some Amsoil instead of cookies as I know your sled is very fast.
Old 11-18-2011 | 04:43 PM
  #48  
FredR's Avatar
FredR
Rennlist Member
 
Joined: Jun 2005
Posts: 10,006
Likes: 804
From: Oman
Default

If what I have read over the years is correct, I get the impression that if the belt jumps a tooth then Fred Astaire and Ginger Rodgers will clatter their knee caps together. Given the cam sprocket has something like 50 teeth, that represents just over 7 cam degrees per tooth or say 15 crank degrees.

Colin's experiments have been limited to a [sensible] range of +/- 5 degrees [crank I presume]. Does anyone know exactly how many degrees of advance or retard need to be applied to cause the valves and pistons to interfere?

I would assume that Porsche in their infinite wisdom designed the cam timing adjustment range such that it would not be possible to cause contact at full range of adjustment providing the cams are indexed correctly.

Ken- another interesting looking piece of kit.

Regards

Fred
Old 11-18-2011 | 04:54 PM
  #49  
Mike Frye's Avatar
Mike Frye
Craic Head
Lifetime Rennlist
Member
 
Joined: Sep 2006
Posts: 8,795
Likes: 6
From: Jersey Shore, USA
Default

Originally Posted by PorKen
Thanks, all!

If you have to ask...click on my facebook page (<-) for the guesstimate retail.
<snip>
FACEBOOK?!?!?

That's crap! I don't do the Facebook thing. Guess I'll have to wait for it to be stocked at a retailer near me.

Hopefully an announcement will be made when they're available.

If your distributor needs to have a count or will allow for pre-orders maybe a thread asking for interested parties would be appropriate...
Old 11-18-2011 | 04:55 PM
  #50  
Lizard928's Avatar
Lizard928
Nordschleife Master
 
Joined: Apr 2003
Posts: 9,600
Likes: 34
From: Abbotsford B.C.
Default

Fred,
1 tooth = 8 deg iirc.
The interference will depend greatly on the camshaft profile.
I have run 0 deg, 5 deg adv, and now 3 deg advance with my cams.
Old 11-18-2011 | 05:00 PM
  #51  
PorKen's Avatar
PorKen
Thread Starter
Inventor
Rennlist Member

 
Joined: Sep 2002
Posts: 10,177
Likes: 412
Default

One cam gear tooth is 7.5 crank degrees.

Folks have gone 2-3 teeth w/o contact w/stock cams.


Originally Posted by Mike Frye
I don't do the Facebook thing.
Don't be timid! It clicks on the
Facebook Post
(or it gets the hose again).

You don't have to be on the facebooks to see the page.
Old 11-18-2011 | 09:39 PM
  #52  
Bill Ball's Avatar
Bill Ball
Under the Lift
Lifetime Rennlist
Member
 
Joined: Mar 2002
Posts: 18,648
Likes: 49
From: Buckeye, AZ
Default

Ken: The Xmas season begins offically the day after Thanksgiving. Get those new parts up for sale!
Old 11-19-2011 | 10:43 AM
  #53  
Bilal928S4's Avatar
Bilal928S4
Drifting
 
Joined: Apr 2011
Posts: 2,879
Likes: 16
From: New Canaan, CT
Default

In the Northeast it looks like Christmas season has already started.
Bilal
Old 11-19-2011 | 10:57 AM
  #54  
FredR's Avatar
FredR
Rennlist Member
 
Joined: Jun 2005
Posts: 10,006
Likes: 804
From: Oman
Default

Originally Posted by PorKen
One cam gear tooth is 7.5 crank degrees.
Ken,

I presume when you are talking about degrees of advance and retard wrt cam timing you are referring crank degrees.

However, with 48 teeth [or whatever] on the cam wheel the 7.5 number logically would be cam degrees surely [i.e. 15 crank degrees]?

Best wishes

Fred
Old 11-19-2011 | 03:59 PM
  #55  
PorKen's Avatar
PorKen
Thread Starter
Inventor
Rennlist Member

 
Joined: Sep 2002
Posts: 10,177
Likes: 412
Default

I should have 7-8 by the first week or so in Dec for the most hard-core early adopters/cam timing ninjas. Since they will be 'pre-production', the price will be lower than the expected retail.

I will post the link on my FB page (<-) when they are ready.



Fred - 24 teeth on the crank pulley, 48 on the cam. Moving the belt one tooth equals ±15° on the crank pulley, ±7.5° degrees on the camshaft pulley.
Old 11-19-2011 | 05:14 PM
  #56  
dprantl's Avatar
dprantl
Race Car
 
Joined: Dec 2003
Posts: 4,477
Likes: 4
From: Atlanta, GA
Default

I'm in for one.

Dan
'91 928GT S/C 475hp/460lb.ft
Old 11-19-2011 | 07:51 PM
  #57  
heinrich's Avatar
heinrich
928 Collector
Rennlist Member

 
Joined: Jan 2003
Posts: 17,270
Likes: 5
From: Seattle
Default

Ken I'm hardcore as always. Please put me down for your alpha tester list
Old 11-20-2011 | 06:29 AM
  #58  
FredR's Avatar
FredR
Rennlist Member
 
Joined: Jun 2005
Posts: 10,006
Likes: 804
From: Oman
Default

Originally Posted by PorKen


Fred - 24 teeth on the crank pulley, 48 on the cam. Moving the belt one tooth equals ±15° on the crank pulley, ±7.5° degrees on the camshaft pulley.
Ken,

Durrgh!

Thanks for the clarification I think I must have been looking at the other cam wheel instead of the crank - either way head well and truly stuck up *ss on that one!

I was interested in just how much flexibility you have before running into interference issues as it does not take much of a slip to be off quite a bit when you start playing with this part of the system. Although I very much like the 32vr tool and used it to verify my timing was set up correctly I would be very reluctant to try adjustments unless I was way off or out of balance as it were [which I am glad to say I am not thanks to the 32vr].

You new tool may well those concerns redundant.

Best wishes

Fred
Old 11-20-2011 | 01:42 PM
  #59  
fbarnhill's Avatar
fbarnhill
Rennlist Member
 
Joined: Mar 2006
Posts: 1,277
Likes: 1
From: Supply, NC
Default

Hey Ken,
I sure as heck want one. ASAP. I will be building the heads and timming them before putting the engine back into the body. I would love to have it before then. Say early December???

Thanks,
Old 11-20-2011 | 01:47 PM
  #60  
fbarnhill's Avatar
fbarnhill
Rennlist Member
 
Joined: Mar 2006
Posts: 1,277
Likes: 1
From: Supply, NC
Default

Thanks Ken, sorry but I didn't see your earlier answer. BTW, I could care less about having them plated... Also, I did not get the heads started this week. My grandkids will be here all next week so it will be 2 more weeks now before I get back to it. I am getting a little excited... Man, I will have an 86.5 with virtually 0 miles on engine.... I will be totally Porkenized...I am trying to build as solid an engine as I possibly can so I don't have to do this again in the near future...



All times are GMT -3. The time now is 05:00 PM.