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Cam removal question
Broke #6 intake rocker arm at the cam end. Everything looks good but will nevertheless at least do a leak down test. Broken rocker end appears to have jammed itself into the camshaft but can't see any significant damage to the cam lobes except about 1mm on the edge of each of the intake and exhaust lobes.
I did build this hot rod 3.4 turbo motor about four years ago but my memory has faded (LOL) so I can't remember what is involved in pulling out the right cam for repair should I decide to do so. I've searched but can't find an appropriate thread. So need some "how to" guidance from those more knowledgeable. Thanks in advance. Johan |
You should have Wayne's book it shows cam R&R and timing in good detail. If you can't remember how to take it out you'll never figure out how to time it without some kind of manual.
Less than $30 off of amazon.ca https://www.amazon.ca/Rebuild-Modify-Porsche-Engines-1965-1989/dp/0760310874/ref=sr_1_fkmr1_1?ie=UTF8&qid=1495284267&sr=8-1-fkmr1&keywords=porsche+engine+rebuilding Pull all the rockers, chain box cover, tensioner, dowel, sprocket, chain, 3 bolts pull off the cover under the sprocket, adjuster shims and woodruff key. The cam should now just pull straight out with a slight turning action as you pull. |
Engine rebuild experience.......
Johan,
As we age our long time memory is not as sharp as when we were much younger. Since you have rebuilt this motor, you have indeed quite an experience in engine rebuilding already. You might not recall today how you did it, but a reminder and refresher will bring your old memory back. It nice to have manuals or books for reference because you will forget things and would not remember things you used to memorized. Are you planning to pull the motor out? Take it out and work on it on an engine stand. Mark has given you good suggestions how it is done. Start the breakdown by setting it to TDC @ Z1 for cylinder #1 and let the fun begins..........Keep us posted. Thanks. Tony |
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Get a new paper gasket and Orings for the cam cap and tensioner & chain cover too. I suggest marking everything so when it is time to set timing you may get lucky and no need to adjust :D http://forums.pelicanparts.com/uploa...1493622810.JPG http://forums.pelicanparts.com/uploa...1490811185.JPG Break a Leg Brother. |
Mark, I recognized the cover of the book and sure enough after much searching I found my copy buried in "other things Porsche". An obvious read. Thanks.
Tony and Draco, many thanks. It's now coming back to me, albeit slowly. :) I will re-read Wayne's book and do the leak-down on Tuesday. Then decide. Cheers, Johan |
Thought an update was in order.
#6 intake lobe appeared OK so I tested the oil tube with compressed air. All 9 orifices appeared good. Went ahead and replaced the rocker and put it all back together, adjusted the the valves. Drove about 500 km and the ticking started to appear again. Guess I can't do valve adjustments very well. So, off came the valve covers and noticed that #6 intake lobe had some coloring (copper-blue). Off came the new rocker.... already marred. http://forums.pelicanparts.com/uploa...1497495277.jpg Obviously I have an oil delivery problem thru the oil rail, I think. I pulled the cam and in fact both #6 intake and exhaust lobes are slightly marred. #4 and #5 are perfect and so are the related rockers. Tomorrow I'm going to clean out the offices with things welder so use to clean their equipment ( name escapes me), blow out the tube from both ends and test the 9 oil rail orifices with oil with 1 bar and 2 bar pressure to simulate idle oil pressure. http://forums.pelicanparts.com/uploa...1497495479.jpg http://forums.pelicanparts.com/uploa...1497495046.jpg I keep looking at the large size of the orfice pointing inwards towards the cam journals at the rear banjo connection and the front screw plug and wondering how there is enough pressure at, say idle (1-2 bar when hot), to feed the 9 small orfice feeding the rockers. Am I missing something here like a restrictor? Can't see one in the PET. Thoughts please. BTW, cam is already in for a reground/hardening and I'm replacing both rockers. Thanks in advance. Johan |
That is because the cam is out. That tube provides oil to the cam journals as well as the lobes.
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Got the regrounded and hardened cam back. Installed it and then jimmied up a pressurized oil line. Used high pressure one way then the other several times to hopefully dislodge any dirt. Collected all the oil and there were several tiny black flakes collected. Repeated the clean out of the nine orfices by poking thin bent wire and repeated the high pressure oil blow out. Successfully tested the spray bar with oil at 15 and 30 pounds pressure and then with gravity feed.
.... .http://forums.pelicanparts.com/uploa...1498435117.JPG Motor all buttoned up with new #6 rocker, gaskets, etc. and now back in the RST. As DRACO suggested I had marked the chain and sprocket positions supported by lots of pics so everything went together without having to redo the timing. Relief to hear the sound of the motor again. :) Thanks guys. Johan |
Brilliant!
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The usual method of dealing with the oil tube is to remove it for cleaning. That way you can get at debris which is larger than the spray holes if the cam is in place to prevent most of the pressure used for blowing things out won't just run through those larger cam journal holes.
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I drilled, tapped, and removed one of the plugs on the end. That gave me total access to the tube without having the hassle of removing and correctly replacing the tube.
If there is debris in the tube you really need full access. AHIK. |
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I recognize that this is rather unconventional and perhaps not fool proof but I'm willing to take that risk. Johan |
Update, 1000km now. No issues. :)
Johan |
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