Cam Cap Oil Flow - Alfa Romeo Bulletin Board & Forums
 
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post #1 of 11 (permalink) Old 05-25-2007, 10:42 AM Thread Starter
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Question Cam Cap Oil Flow

I have a pro-shop rebuilt head in a '77 Spider. Upon assembly and running the car there is a significant amount of what I would call 'squeeking' coming, I believe, from the cam cap area, in spite of being lubed up nicely preassembly. I have removed one of the cam caps to repair a stripped thread that holds the cam cover stud and in the process was introduced to the geometry of the system, with the cam caps being held in place by two undersized studs with short tubes running up the interface between the head and the cam cap to hold the caps in place. I am supposing the undersized studs allow oil to flow up the holes in the head to the top of the cam cap bolt, but where to from there?

My question is... how are the cam caps oiled in this arrangement? My short tubes were quite firmly in place in the head, is this OK? Is there a modification one can make to the cap to improve the oilflow? (drill tiny holes from the inside of the cap to the stud holes?) I want to stop the squeeking!!!

PS - I think the shop did a reasonable job, and in the process of dissassembling and re-assembling the head stamped the cam caps with numbers to identify them, so I presume they are all in the correct location.

I appologize if this is covered in a previous post, but I can't find it if it is.

Ian Mac
'73 Spider - Rebuilding Engine

Last edited by ianmac; 05-25-2007 at 10:44 AM. Reason: Added PS
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post #2 of 11 (permalink) Old 05-25-2007, 11:32 AM
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The cam journals are pressure fed via an oil hole at the bottom of each cam journal. The cam cap studs' sole purpose is to retain the cam caps.
Thoughts on the squeeking;
cam caps not in the proper location or orientation
insufficient lubrication
cam cover retaining stud(s) too long
incorrect cam caps

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post #3 of 11 (permalink) Old 05-25-2007, 11:48 AM Thread Starter
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Oil holes plugged?

I wonder if the grease that was used to lube the system has plugged the holes in the bottom of the cam journals? It was that really thick red stuff that machinists love to use.

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'73 Spider - Rebuilding Engine
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post #4 of 11 (permalink) Old 05-29-2007, 01:47 PM
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Or maybe the lobes squeaking/scraping on the cam followers. They receive their lube oil as the overflow out from the pressurized cam bearings, and so if nothing was getting to the bearings, nothing was leaking from them and getting to the followers. Were the galleries there somewhat full of oil? They ought to be approx half full.

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post #5 of 11 (permalink) Old 05-29-2007, 01:58 PM Thread Starter
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Yup, they are about half full, as expected. I'm going to try a stethescope and see if I can locate the sound more precisely.

Ian Mac
'73 Spider - Rebuilding Engine
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post #6 of 11 (permalink) Old 05-29-2007, 05:22 PM
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Squeek?

The cams & caps are not going to squeek. If the surface of a cam follower is that bad it should have jumped put at you and even then I can`t say I heard one squeek.
I would think that damage done during assembly/disassembly or either a keeper loose and about to come off-out which will be a real problem. I would not start it again till the cams & cam followers are out to verify. Better safe than broken...

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post #7 of 11 (permalink) Old 05-30-2007, 02:01 PM
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PS - I think the shop did a reasonable job, and in the process of dissassembling and re-assembling the head stamped the cam caps with numbers to identify them, so I presume they are all in the correct location.


every cam cap is stamped with a number org from the faktory.


the caps and studs can handle 13 mm lift lobs, the problem is not too thoque them more than org and you find out very ezie because you pull the threats off, thoque is 14.2 / 16.3 Lb ft.

the caps are numberd 1 is front off engine inlet ten too the back and from back too front on exaused side ending with 6 on the front off the engine on the exaused side.


caps are only useable for the head it was made for, if you take ather you need too line bore the caps.


.
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post #8 of 11 (permalink) Old 05-30-2007, 10:21 PM
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To tight of a cam cap will cause galling on the inside of the cap due to the lack of lubrication. The cap will be squeezed against the cam closing up the tolerance. The later 80's cam shafts had the front cam journals turned with a groove to improve oiling in this area.
Your squeeking is coming from another area. Might be the alternator bearing? Or a water pump bearing that has gone dry?
Han is correct, you can not swap caps from another head because they are line bored as a set to the head at the factory.
Keep searching, the sound will manifest itself if you use a rubber hose as a stethescope.
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post #9 of 11 (permalink) Old 05-31-2007, 03:56 PM
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You might need to check the chain tensioner. It is fed oil from the chain as it rotates, and if the lube holes to the bearing are clogged or the bearing is worn.... Good luck
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post #10 of 11 (permalink) Old 06-03-2007, 03:45 PM
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squeek

Sounds like the rubbing block on the points needs lube . Been there , done that .
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post #11 of 11 (permalink) Old 06-04-2007, 09:21 AM Thread Starter
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No Point(s)

I just picked up a mechanics stethescope on the weekend which should help locate this problem. I'm pretty sure that it's not my points, since they are sitting in a box under my workbench and have been since I installed an electronic, pointless (or is it point-free?) ignition.

Ian Mac
'73 Spider - Rebuilding Engine
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