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

WP/TB change question

Thread Tools
 
Search this Thread
 
Old Dec 21, 2014 | 07:09 PM
  #1  
Jetdriver69's Avatar
Jetdriver69
Thread Starter
Banned
 
Joined: Apr 2013
Posts: 850
Likes: 6
From: Humble, TX
Default WP/TB change question

Just started on the WP job and drained the coolant, removed hoses on the 82.

I rotated the engine to get TDC on the harmonic balancer and cam gears before locking the flywheel.

My left cam gear is not perfectly lined up with the notch and V pointer, it is about a 1/2 tooth off to the right as you are looking at the gear from the front.

Prior to this, the engine ran great with no misses. Should I try to rotate the cam assembly once I remove the belt to get perfect alignment or leave well enough alone? Haven't removed the right cover yet to see where the right gear is at.
Thanks!
Attached Images
File Type: jpg
IMG_0437.jpg (137.7 KB, 250 views)
File Type: jpg
IMG_0438.jpg (110.5 KB, 257 views)
Reply
Old Dec 21, 2014 | 07:29 PM
  #2  
Gman1003's Avatar
Gman1003
Intermediate
 
Joined: Nov 2014
Posts: 49
Likes: 0
From: Matawan, NJ
Default

JetDriver,

I am in the middle of the TB/WP on my 86. My Passenger side cam is also about 1/2 a tooth off. I am new at this, but I think when you go to install the new TB you will likely need to rotate the PS cam to get it into the new timing belt notch. I'm sure others with extensive experience in tis will chime in here as well.

Gman
Reply
Old Dec 21, 2014 | 07:31 PM
  #3  
GregBBRD's Avatar
GregBBRD
Former Vendor
 
Joined: Feb 2005
Posts: 15,228
Likes: 2,529
From: Anaheim
Default

They never line up perfectly...too many pieces can be moved slightly either way (like the cover that the mark is cast into.

As long as you can't move the gear one tooth and make it any better.....you've got it in the correct place.

Your cam gears are not adjustable, like the 1985 and later gears. Tighten them down, set them so that the notch in the gear is as close to the pointer as possible....and forget it.
Reply
Old Dec 21, 2014 | 07:35 PM
  #4  
GregBBRD's Avatar
GregBBRD
Former Vendor
 
Joined: Feb 2005
Posts: 15,228
Likes: 2,529
From: Anaheim
Default

Originally Posted by Gman1003
JetDriver,

I am in the middle of the TB/WP on my 86. My Passenger side cam is also about 1/2 a tooth off. I am new at this, but I think when you go to install the new TB you will likely need to rotate the PS cam to get it into the new timing belt notch. I'm sure others with extensive experience in tis will chime in here as well.

Gman
Your cam gears are adjustable....they have a rather large elongated key slot in them that can be moved and then locked down into that position by the front bolt.

You will need to set your cam timing correctly.

Do not simply line the marks up....this will not work!

Porken makes a clever tool to do this....which eliminates the necessity of removing the valve covers to do this job.

Liftbars.com is his Website, I believe.
Reply
Old Dec 21, 2014 | 07:43 PM
  #5  
The Deputy's Avatar
The Deputy
Drifting
 
Joined: Dec 2014
Posts: 2,177
Likes: 4
From: Michigan
Default

Out of curiosity...how many miles are on the belt?

And, I would think…if your tension was somewhat out of adjustment…it could let the belt be off that much. A new belt, properly tensioned will probably bring he marks closer.
Reply
Old Dec 21, 2014 | 07:47 PM
  #6  
Gman1003's Avatar
Gman1003
Intermediate
 
Joined: Nov 2014
Posts: 49
Likes: 0
From: Matawan, NJ
Default

Greg,

Thanks for chiming in. So when I install my new belt, if the belt is off on the Passenger side cam gear by 1/2 tooth, I should not rotate that cam gear the 1/2 tooth to make the gear mark line up with the notch in the back of the cam cover housing and slip into the new belt? If the belt won't line up perfectly without moving the cam gear that little bit, do I need to do something else like you mention above?

Thanks, Gman
Reply
Old Dec 21, 2014 | 07:58 PM
  #7  
uncre8tv's Avatar
uncre8tv
Racer
 
Joined: Sep 2013
Posts: 303
Likes: 2
From: NWMO
Default

Originally Posted by GregBBRD

You will need to set your cam timing correctly.

Do not simply line the marks up....this will not work!
Greg - for clarification - if you mark where your belt came off, (gear to cover) you can just keep the gear in that spot (even if it springs one way or the other, move it back as you put the new belt on) and you will be ok. The timing set is only if you have NOT preserved your original marks... right?
Reply
Old Dec 21, 2014 | 08:16 PM
  #8  
Jetdriver69's Avatar
Jetdriver69
Thread Starter
Banned
 
Joined: Apr 2013
Posts: 850
Likes: 6
From: Humble, TX
Default

Thanks Greg!

My belt only has about 3000 miles and about 14 months.

The rebuilt metal impeller WP that was about 4 years old and 3000 miles was reused after an engine rebuild.

Yeah I know, should of got a new Laso pump while I had everything apart. Now the old pump is leaking, so out it comes. Penny wise and pound foolish I guess....

My old worn alloy cam gears have really started to fray the new TB. I scored a nice set of steel gears that will be installed with the WP job.

Everything will be dismantled tomorrow and hopefully WP installed. Let the RTV cure 24 hrs, install and tension the belt and reassemble on Tuesday.

Hopefully all will go well so I can make the Xmas gathering 28 Dec.
Reply
Old Dec 22, 2014 | 01:39 PM
  #9  
antsmands's Avatar
antsmands
Racer
15 Year Member
 
Joined: Sep 2009
Posts: 382
Likes: 0
From: Chicago, IL.
Default

Originally Posted by Jetdriver69
Just started on the WP job and drained the coolant, removed hoses on the 82.

I rotated the engine to get TDC on the harmonic balancer and cam gears before locking the flywheel.

My left cam gear is not perfectly lined up with the notch and V pointer, it is about a 1/2 tooth off to the right as you are looking at the gear from the front.

Prior to this, the engine ran great with no misses. Should I try to rotate the cam assembly once I remove the belt to get perfect alignment or leave well enough alone? Haven't removed the right cover yet to see where the right gear is at.
Thanks!
Looks fine to me, mine was just like that when I did my WP job. I just put it back in the same position.
Reply
Old Dec 22, 2014 | 01:52 PM
  #10  
James Bailey's Avatar
James Bailey
Addict
Lifetime Rennlist
Member
 
Joined: Feb 2009
Posts: 18,061
Likes: 10
Default

Originally Posted by uncre8tv
Greg - for clarification - if you mark where your belt came off, (gear to cover) you can just keep the gear in that spot (even if it springs one way or the other, move it back as you put the new belt on) and you will be ok. The timing set is only if you have NOT preserved your original marks... right?
That ASSUMES that who ever did it BEFORE had it timed correctly.......big assumption, what you know is only that the car will run that way !
Reply
Old Dec 22, 2014 | 02:25 PM
  #11  
FredR's Avatar
FredR
Rennlist Member
20 Year Member
 
Joined: Jun 2005
Posts: 10,572
Likes: 1,027
From: Oman
Default

I presume with the earlier motors such as yours you do not have the issue of interference so setting the flywheel at 45 degrees as we do with the interference [32 valve?] motors is not required.

Just a point of observation for clarity.

Regards

Fred
Reply
Old Dec 22, 2014 | 04:38 PM
  #12  
mark kibort's Avatar
mark kibort
Rennlist Member
20 Year Member
 
Joined: Feb 2003
Posts: 29,828
Likes: 218
From: saratoga, ca
Default

the marks are always off a bit.. adjustment of the cams is independent of this phenom, as its a function of the belt and the mechanical bits all involved.
best to get it close, and this should be obvious, and then adjust the cams... pretty hard to not pick the right spot with the cam gears. one way will be closer than the other, so it will be obvious. usually, you will never be more than a 1/4 tooth off the cover or head marks, again, which is fine.
Reply




All times are GMT -3. The time now is 04:29 PM.