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Chain fence eating turbo
Join Date: Dec 2008
Location: Austin, TX
Posts: 9,131
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As I was putting my camshafts in and sliding on the camshaft end-plates/retaining plates, I noticed the end-plates did not look like they line up with the chain housings.
I know "Cgarr" shaved my heads some (due to my knuckleheaded mistake) but can you really see this with the naked eye - this misalignment? Will removing the chain housing gaskets really make the alignment ok?
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Cory - turbo'd '87 C3.2 Guards/Blk, 3.4, 7.5:1 CR, 993SS cams, Borg-Warner S366 turbo @ 1.2-1.5 bar, Treadstone full bay IC, 70mm TB, TiAL F46 WG, HKS 1 1/2" BOV, twin 044 pumps, MicroSquirt AMP'd w/GM smart coilpack, Bilstein coilovers, Tramont replica Speedlines (285's rr, 225's frt), Big Reds frt, 993 rr., tower brace, MOMO wheel Last edited by Tippy; 05-06-2011 at 06:29 AM.. Reason: **Follow up question** |
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Registered
Join Date: May 2008
Posts: 726
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When you put together all parts do the cams touch the cam cover plate? When parts are machined like the case half's, the case cylinder surface and the head cylinder surface this moves the cams closer to the center of engine. Its best to use larger cylinder base gaskets to keep the cam centered through the chain boxes.
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Case work like cylinder spigots surfaced, case half's surfaced and cylinder head surfacing will move the cam closer to the engine center-line. If your chain housing is now off center with the cam you need measure the amount of offset then have that amount (less gasket thickness) removed from the housing end that bolts the the engine case. Then you can use the stock gasket and all will be good. I had this problem ounce and just sealed the chain housing to the case less gasket and it ended up having a leak.
Other may have a different solution.
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Mark Jung Bend, OR MFI Werks.com |
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Registered
Join Date: May 2008
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Yes you can have a machine shop shave the chain housing down to compensate. I've done this once, it will also make the tensioner push out more to tighten the chains. If everything is together and you don't want take it back apart then that is a option. I have a pair of mag housings that have are shaved about 0.040". Valve to piston clearance might be a issue.
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Chain fence eating turbo
Join Date: Dec 2008
Location: Austin, TX
Posts: 9,131
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I have to pull it down and look again as I'm not sure which direction the misalignment is but once I torqued the cam bolt, it felt like it was binding. I thought originally it was too much Loctite 574 but then I remembered seeing the misalignment.
Just curious if this is seen with the naked eye and a simple removal of the chain housing gaskets would do the trick. |
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abit off center
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I just did a top end on my 3.2 this spring and took .008 off my heads and did not have any problem with alignment. When I tried to draw the end plate in with the bolts it was miss-aligned too. What I did was just start the bolts as a guide and pressed/worked the plate all the way in place flush with lube on the o-ring then ran the bolts all the way in. There should be plenty of give in the o-ring to take up .008 The factory limit is .010 and maybe that's why the limit is .010 because anything more then you start having problems with the plate? What about making the holes in the plate just a tad bigger for more adjustment?
I got a set of race heads in once and they had .018 off the surface, then you need to do a lot of adjusting to the chain boxes and the chains too as they will be to long sometimes.
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______________________ Craig G2Performance Twinplug, head work, case savers, rockers arms, etc. Last edited by cgarr; 04-28-2011 at 06:25 AM.. |
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Porsche Tech
Join Date: Apr 2011
Location: Canada Ontario
Posts: 2
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Hi Tippy , If u have a good machine shop that know what they r doing u should have no problems , depending how much they took away ,then u need to address the problem . I
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Chain fence eating turbo
Join Date: Dec 2008
Location: Austin, TX
Posts: 9,131
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Quote:
I need to quit pestering you guys and just rip it apart and look. ![]() Quote:
I think it is just the angle of what I was looking at. When I get some time, I will rip into to it and investigate.
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Cory - turbo'd '87 C3.2 Guards/Blk, 3.4, 7.5:1 CR, 993SS cams, Borg-Warner S366 turbo @ 1.2-1.5 bar, Treadstone full bay IC, 70mm TB, TiAL F46 WG, HKS 1 1/2" BOV, twin 044 pumps, MicroSquirt AMP'd w/GM smart coilpack, Bilstein coilovers, Tramont replica Speedlines (285's rr, 225's frt), Big Reds frt, 993 rr., tower brace, MOMO wheel |
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Chain fence eating turbo
Join Date: Dec 2008
Location: Austin, TX
Posts: 9,131
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**UPDATE**
I pulled it apart and indeed saw I put too much Loctite 574 on the camshaft end-plate gaskets causing some of the binding........but......... The thrust face of the camshaft (where the thrust washer mates) is not in the center of the chain housing as I originally posted. It shows a larger gap towards the 9 to 12 o'clock area. Fine, so I pull the chain housing gasket out and reinstall the housing back on and mock up the end-plate to see how it looks. Well, it fixed the side-to-side gap but there is still a larger gap at the top versus the bottom. I'd say a gap of .150" on the top versus .080" on the bottom (total guess by eyeball!!!) for reference. So, I decided to pull the right side apart and remove the chain housing gasket also. Well, when I did, I saw the side-to-side gap is pretty good already with the gasket installed, but same as the left side, there is a larger gap at the top than there is at the bottom. My questions are: 1. Have you seen an engine that needed one chain housing gasket on one side and none on the other?!?! 2. Is this gap at the top larger than the bottom normal?!?! I cannot see how you can fix this without major machine work..... Please help! TIA guys ![]()
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Cory - turbo'd '87 C3.2 Guards/Blk, 3.4, 7.5:1 CR, 993SS cams, Borg-Warner S366 turbo @ 1.2-1.5 bar, Treadstone full bay IC, 70mm TB, TiAL F46 WG, HKS 1 1/2" BOV, twin 044 pumps, MicroSquirt AMP'd w/GM smart coilpack, Bilstein coilovers, Tramont replica Speedlines (285's rr, 225's frt), Big Reds frt, 993 rr., tower brace, MOMO wheel |
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Chain fence eating turbo
Join Date: Dec 2008
Location: Austin, TX
Posts: 9,131
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Steve, Henry, or anyone????
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Cory - turbo'd '87 C3.2 Guards/Blk, 3.4, 7.5:1 CR, 993SS cams, Borg-Warner S366 turbo @ 1.2-1.5 bar, Treadstone full bay IC, 70mm TB, TiAL F46 WG, HKS 1 1/2" BOV, twin 044 pumps, MicroSquirt AMP'd w/GM smart coilpack, Bilstein coilovers, Tramont replica Speedlines (285's rr, 225's frt), Big Reds frt, 993 rr., tower brace, MOMO wheel Last edited by Tippy; 05-09-2011 at 10:08 AM.. |
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Registered User
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Cory, I understand what your saying so I pulled some parts off the shelf to take a look. To me, there is some room for error with the cam being centered in the thrust plate. If there was a big problem, I don't think the thrust plate could be installed at all.
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Mark Jung Bend, OR MFI Werks.com |
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Chain fence eating turbo
Join Date: Dec 2008
Location: Austin, TX
Posts: 9,131
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Quote:
Yeah, I see your point. If it was too far off, the thrust washer would not even go into the housing and seat against the cam thrust face. But, once I torqued the sprockets, the cams got tight. Hopefully it was just my over zealous use of Loctite 574. Just wanting to make sure others have seen this and if any corrections needed to be made. But, I think it is a little ghetto to have one side with a gasket and other without. So, that is why I wanted to hear others and what they've done. Unfortunately, to have the cams centered the best as possible, I have to have it in this configuration.
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Cory - turbo'd '87 C3.2 Guards/Blk, 3.4, 7.5:1 CR, 993SS cams, Borg-Warner S366 turbo @ 1.2-1.5 bar, Treadstone full bay IC, 70mm TB, TiAL F46 WG, HKS 1 1/2" BOV, twin 044 pumps, MicroSquirt AMP'd w/GM smart coilpack, Bilstein coilovers, Tramont replica Speedlines (285's rr, 225's frt), Big Reds frt, 993 rr., tower brace, MOMO wheel |
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Registered
Join Date: May 2008
Posts: 726
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The cams don't need to be centered in the hole, just not touching the plate. Not usings the gasket will be asking for a big leak.
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Chain fence eating turbo
Join Date: Dec 2008
Location: Austin, TX
Posts: 9,131
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Wayne's book states you can leave out the chain housing gaskets?
Anyone done this with success? |
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Registered User
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Yes I did on my 2.7 short stroke engine. The only oil leaks I have are on the chain housings where it bolts to the case. Next time I will have the chain housing machined so I can use the gasket.
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Mark Jung Bend, OR MFI Werks.com |
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abit off center
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If you have access to a surface table or something real flat it does not take long to remove 5 thou on these chain boxes. You can also tell then if its warped. I always like to give them a quick surface since there is only 4 bolts holding them in place and not much meat on them for good clamping.
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______________________ Craig G2Performance Twinplug, head work, case savers, rockers arms, etc. |
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Author of "101 Projects"
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-Wayne
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Wayne R. Dempsey, Founder, Pelican Parts Inc., and Author of: 101 Projects for Your BMW 3-Series • 101 Projects for Your Porsche 911 • How to Rebuild & Modify Porsche 911 Engines • 101 Projects for Your Porsche Boxster & Cayman • 101 Projects for Your Porsche 996 / 997 • SPEED READ: Porsche 911 Check out our new site: Dempsey Motorsports |
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Chain fence eating turbo
Join Date: Dec 2008
Location: Austin, TX
Posts: 9,131
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Quote:
Quote:
![]() Yeah, I know. Whoever rebuilt my engine in the past (no records) did some weird things, like only replace one timing chain and cam sprocket.
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Cory - turbo'd '87 C3.2 Guards/Blk, 3.4, 7.5:1 CR, 993SS cams, Borg-Warner S366 turbo @ 1.2-1.5 bar, Treadstone full bay IC, 70mm TB, TiAL F46 WG, HKS 1 1/2" BOV, twin 044 pumps, MicroSquirt AMP'd w/GM smart coilpack, Bilstein coilovers, Tramont replica Speedlines (285's rr, 225's frt), Big Reds frt, 993 rr., tower brace, MOMO wheel |
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