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Functionista
 
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Maybe post a pic of rocker face. Geometry might be off? Wearing close to heel or nose, or in the middle?
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Old 12-25-2017, 10:21 AM
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Old 12-25-2017, 10:32 AM
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if the cams have no oil left and right they will be more likely ......in the middle...
Old 12-25-2017, 10:45 AM
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Did not understand quote below. With 20w-50 mineral my oil pressure is very high when cold, to the point where it limits progress in traffic. Anyone can recommend a 5w-40 or 10w-40 synthetic? With zddp enough to protect cams....

Quote:
Originally Posted by proporsche View Post
the oil should be at the highest point when cold, your is not...
Ivan

Last edited by trond; 12-25-2017 at 11:31 AM..
Old 12-25-2017, 11:27 AM
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my bad..i did not understand this

When cold I can hardly make 50 mph in fifth before the oil pressure hits max on the gauge...

Ivan

do you mean in fifth gear traveling 50mph?
Old 12-25-2017, 11:31 AM
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besides all out talk ...you have a problem with delivery to the cams ,i certainly doubt is has to do with the thickness of oil...
Old 12-25-2017, 11:36 AM
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Correct. When cold oil pressure hits max on the gauge at approximately 50 mph in fifth. Obviously not the same when hot. What could cause oil starvation in the heads? Difficult to install spray tubes wrong and there is good oil pressure at any temperature. I could start engine with cover off and see how much oil is splashing about
Old 12-25-2017, 11:49 AM
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Yup that is the way to go just before you do put some tube-hose on the further end on the camshaft housing and in the front when you take the bolt off put some hose an pour gas in it .It should come out on the other end into a bottle .So you can see if you have some mess inside.

...i had a problem once with 993 ..i had to start it with the cover of.I found out later send inside my tubes.the machine shop send-blasted my heads and i did not know about it.
When i talked to them they said they were sorry, apprentice did the job....i went trough 2 set of cams because of this little boy screw up.
So concentrate on the delivery of oil..
Ivan
Old 12-25-2017, 12:02 PM
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Quote:
Originally Posted by trond View Post
I determined they were stuck open after splitting engine and applying air pressure to the oilways. 4 opened around 3 bar while 2 were always open. Ok?
Air is a very deceptive way to try and test the opening of the squirters. In my testing on factory new squirters they opened with as little as 10 psi of air - ~.75 bar. These were BRAND NEW squirters, and not just one of them either.

They are 100% open using 1.1 bar or so of water pressure and begin their full spray pattern at about 2 bar. Again, this is with brand new squirters. The only reasons old ones open at such high pressures is they are full of crap and oil varnish. The spring within the stock quirter is less powerful than you would find inside a typical ball point pen.
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Old 12-25-2017, 03:57 PM
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Why not get a stick on silicon heater pad for the oil tank. Amazon and eBay have plenty of options. I would say cold starts in Norway on 20/50 oil is your problem. 100 watt heater turned on a few hours before your trip should help. And or switch to a thinner synthetic oil.
Old 12-25-2017, 04:23 PM
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Quote:
Originally Posted by trond View Post
..... I installed new stock cams and replaced only the dodgy rockers........Two years later again both of the stock cams are still OK but I had to replace 5 rockers.......
Trond,

Before we get carried away and jumping to conclusions that may not be correct, can you clarify a number of things please?
  1. Whenever you replace the cams, did you reface those rockers you didn't replace?
  2. Do the new rockers last longer or look less worn than the refaced ones?
  3. Do you think whoever refaces the rockers does it squarely? ie Are all the rocker faces failing on the same side or is there some other reoccurring issue?
  4. Are you running non standard tension valve springs?
  5. Is the cam lobe contact nicely in the middle of the rocker face?
  6. How are you bedding in your new cams and rockers each time?



I suspect the root cause is not related to engine oil at all.

Regards
Old 12-25-2017, 07:38 PM
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When I first changed to an aftermarket cams I got resurfaced rockers to go with it. I ran in the engine with Millers break-in oil observing the 2000 rpm rule for the first half hour. More or less. A few years later when I decided I liked the stock cams better after all and replaced the hotter cams I found that both the cams were in a sorry state with about half of the cam lobes scuffed and properly worn, along with the rockers on those lobes. I did not replace the rockers that looked good because because I believed the reason for failure could be bad geometry and/or material defects. I remember several of the rocker/lobe pairs were worn mostly on one side, looking like they did not contact cam lobes squarely and these ones were all junked.

With the new stock cams (came from FVD, not Porsche) I installed new rockers in about half of the positions (replacing only the bad ones). I used the car for about 2-3 years then took it apart again this May for 3.2SS conversion. I found again that 5-6 rockers were bad, both of the stock Porsche ones and resurfaced ones from previous installation. Unfortunately I did not take notes of which ones failed but I was relieved in a way to see that both stock and resurfaced had failed. At least my decision to re-use was not completely wrong..... I have again kept the good ones paired to the same lobes, and got new ones to replace the bad ones. I realize I should have replaced all rockers with the cams to reduce risk of damage but I had a sinking feeling there is something wrong here that I don't understand and had a feeling it was pointless to throw more money at it as the root cause has not been established and it all will need to be replaced in a few years anyway. i guess I had given up a bit.

My valve springs are stock and I don't rev the engine high (hence the stock SC cams).

I too has a bad feeling about it that my problem might not be related to just viscosity/cold starts but I have not been able to find anything else. Oil types are good, I never abuse a cold engine, oil pressure is good (and no other engine damage) and I have had spray bars out and re-checked oil ways and spray pattern both with bars in situ and on the bench. Never found anything wrong.

Spray bars are possible to install upside down but it is quite obvious with the spray pattern not matching the cam lobes in any way and hitting the valve covers instead.

What else could it be. Bad practice with old rockers on new cams, possibly a material/geometry issue with the previous aftermarket cams. Or oil viscosity/cold starts


  1. Whenever you replace the cams, did you reface those rockers you didn't replace?
  2. Do the new rockers last longer or look less worn than the refaced ones?
  3. Do you think whoever refaces the rockers does it squarely? ie Are all the rocker faces failing on the same side or is there some other reoccurring issue?
  4. Are you running non standard tension valve springs?
  5. Is the cam lobe contact nicely in the middle of the rocker face?
  6. How are you bedding in your new cams and rockers each time?



I suspect the root cause is not related to engine oil at all.

Regards[/QUOTE]
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Old 12-26-2017, 02:31 AM
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Don't give up yet!

Are you able to post some photos of the damaged rocker faces and the cam lobes please?

I assume the engine is still pulled down? ie unassembled.
Old 12-26-2017, 02:58 PM
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I am dubious that this is an oil viscosity issue. I used Mobile 1 20W/50 for some years before they dropped the ZDDP and I retired the car from street use (because of the headers and stingers and to save on insurance). It was my ski car, so had its share of fairly cold weather starts in the mountains, or here in Boulder CO during cold snaps. And my drive to work car much of the time. Cams were fine when I rebuilt it after 10 or so years of daily driving and track events.

If these engines were inherently super sensitive to viscosity I think we would all have heard about it long ago. The cams are kind of at the far end of the oil distribution chain, but still with good pressure (and no restrictors) should get plenty even for a cold start.

I'm pretty sure if you had clogged spray bars you'd have noticed much more dramatic wear - as in lobes worn down to the base circle, with little thin parts still sticking up on each side of the lobe showing its former outline. It appears that's what happens when one spray bare hole is completely blocked - I saw a cam once which had suffered from that - it took a very short time, as once the hardening is worn through the wear is rapid with no lubrication.

I would, though, be careful about starting the engine with a valve cover off. One reads tales of that leading to an awful mess, while leaving a chain cover off to observe the chain is feasible. I've not tried either.

The fact that this happens to some but not all lobes/rockers does suggest a cam perhaps not ground correctly, or some other rocker/cam misalignment, which is why guys are asking about pictures.

The three cam journals get their lube through the spray bar too - do they look fine? If they do, that's one more point suggesting it is not the oil.

Your oil pressures also seem high - what is max on the gauge in your car? 5 bar? Are you really in 5th in cold weather at 80 kph? I'm trying to remember what the oil pressure regulator spring opens at.

Guessing, like everyone else.

Walt
Old 12-26-2017, 10:54 PM
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Thanks for good inputs everyone. Cam journals look perfec, and now on the last teardown so did the cam lobes . Yes, I did notice uneven wear on some of the rocker pads/lobes and believe there could have been a geometry issue. I am travelling now and will see if I will post some pictures mid January when I get home.
Old 12-27-2017, 01:14 AM
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Just remember high oil pressure doesn't always mean high flow.
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Old 12-28-2017, 08:01 AM
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^ ^ ^
Agree . . .
Our engine tech says high idle RPM to warm up engine to provide better oil flow to cams . . . 1500-2000 RPM
We also had pitting on cam and rockers probably caused by low RPM idle warm up.

Regards,
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Old 12-28-2017, 08:31 AM
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zinc issue? Mobil 1 V-twin has a very high level of zinc, designed for air cooled engines and a v=twin does not have a wet clutch. Should be perfect but very expensive oil.

You are not supposed to use racing oils as they contain no detergents and certain additives.

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Old 01-08-2018, 11:05 AM
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As long as you start the engine and do not allow it to idle under 2000 RPM until warm you have not caused the issues.

However there are other factors that could be in play here.

Its not an oil issue but it could be a lack of oil.

If the lash is too small or not there, then there is no oil present removing any of the heat created in this design. This design is one of the most critical when it comes to an oil film. It is a sliding finger design. If there is no oil present when on the cam heel, valve closed, there will be no oil present when the cam lobe slides across the rocker face.

Have you checked the coil bind distance? This too could be the cause. Not really possible but it should be checked. I would think after these sorts of miles, you should see a broken spring.

If the rockers were ground improperly this too can cause this problem as does the way the cam lobe was ground. If the oil spray bars are clear, then I would suspect the start up first, then the lash, then the rocker and cam grinding.

Spring force does not really cause this until you get some really high seat pressures which should never be present in any 2V engine. In this case stock springs are used which should be giving around 70-80 PSI on the seat and around 260- 280 PSI over the nose.
Old 01-08-2018, 08:06 PM
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Are you using silicon gasket sealer on gaskets or case? I have almost always found plugged tube squirtters when worn rockers and cams, usually from silicon sealer tabs hanging out the holes, sometimes they free themselves but the damage is already done. I have seen it plug crank oil passages too.
Old 01-08-2018, 08:46 PM
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