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Bird. It's the word...
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Reface Rocker Arms?
I have reground cams to go into my new engine but have not done anything to my rockers...
Is this bad, why, etc... Cheers
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John Forcier Current: 68L 2.0 Hotrod - build underway |
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No not bad at all as long as they are still in spec.
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66 911 with S engine 2008 Westfield XTR2 |
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John,
My understanding is that you need to reface or replace the rockers so the surfaces wear in properly. I was told that if you don't you will see premature wear on both surfaces. Dave |
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Irrationally exuberant
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As I understand it, the cam and the rocker surfaces wear harden so replacing just one can create a situation where the old "hard" one "machines" the other. Ideally, the machine shop would have a special jig to finish the rockers to the right profile. I'm probably going to H**l for it, but years ago I ordered some rebuilt rockers that never arrived (after waiting for a month) so I used some fine sandpaper (600 I think) to remove the surface of the rocker or at least I tried. I don't know how deep the hardening went so who knows if I got through to the "soft" metal. I never noticed any unusual cam wear even with high pressure valve springs. The rockers should be riding on a film of oil anyway.
I don't know if rebuilding/rebushing rocker arms makes financial sense these days. -Chris
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'80 911 Nogaro blue Phoenix! '07 BMW 328i 245K miles! http://members.rennlist.org/messinwith911s/ |
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Shop around for rocker arm prices.. some are way too high.
Always use new or redone rockers on a new set of camshafts. The 600 grit paper trick is common. It removes the glaze on the rocker face, kind of like whats found on a disc brake rotor. Most of all it will bring to your attention any irregularities in the rocker arm face. The worn out bushings can have taper. Meaning one side of the rocker will touch the lobe. Permatex sells "Prussian Blue" which is a machinsts lay out die. Wipe the lobes with this and turn the engine over. If you do not have at least 80% contact between rocker arm and cam lobe replace that rocker arm.
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John Dougherty Dougherty Racing Cams |
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This works for me ....you do as you want- break out your dremal and jewery buffing compound (s) and go to work till you get a high luster. i do it to my cam lobes also.
No problems so far and is a savings right now.......( been doing this to all kinds of recipicating masses fpr a long time) Except turbins, we use wallnut shells!
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D troop 3/5 Air Cav,( Bastard CAV) and 162 Assult Helicopter Co- (Vultures) South of Saigon, U Minh Forest, Delta, and all parts in between |
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Follow Camgrinder's advice. I replaced all of mine with new. Once the hardened surface wears off, it'll be hard to keep a valve adjustment like a hardened rocker gives you. The old wear pattern also wears into the new cam profile. If it isn't square to the lobe, it kind of botches things up. I kind of worry alot, but I'm patient so It was easy for me to save up and replace them. It set me back, but it was worth it to me and the next owner, if there ever is one.
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78SC coupe, Silver Metallic Last edited by oneblueyedog; 06-21-2004 at 07:02 PM.. |
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Bird. It's the word...
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I hoped John D would chime in. I have some bearing blue and will follow that advice.
Thanks to you all.
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John Forcier Current: 68L 2.0 Hotrod - build underway |
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Author of "101 Projects"
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New cams must use new rockers. Used cams must use the same rockers on the same lobes. Otherwise, you will get premature cam/rocker wear...
-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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Now in 993 land ...
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I want to say it stronger: If you cheapen out on new rockers, you may have to live with a flat cam or two. You guys may have more time than money, but new cams are $300+, so even if you have time to go back in, you'll be $300 short and still have to buy new rockers.
![]() Play it safe, do it right and leave the dremel for your dog's nails. ![]() George |
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up-fixing der car(ma)
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Sooo, looks like brand new rockers are $950 ('72), for just the rocker arms (no shafts or hardware but that should be reusable as-is)...Is there a place that redoes rockers ? TIA
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Scott Kinder kindersport @ gmail.com |
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Irrationally exuberant
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Quote:
-Chris
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'80 911 Nogaro blue Phoenix! '07 BMW 328i 245K miles! http://members.rennlist.org/messinwith911s/ |
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Get your rocker arms refurbished (resurfaced and new bushings) its half the price of new ones! I had mine done at Competition Engineering they look like new.
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David |
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Like I said -do what you want,,I have polished cams and rockers a lot ( the ones that are servisable).......like most things on this board a lot of peo turn some of this stuff into a religion and say prayers to thir P. god b4 opening a tool box.
A lot of this stuff you can make simpler. Now if you had a known bad cam or banged up pitted rockers you might want to consider other options. Works for me .....can that be wrong??
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D troop 3/5 Air Cav,( Bastard CAV) and 162 Assult Helicopter Co- (Vultures) South of Saigon, U Minh Forest, Delta, and all parts in between |
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up-fixing der car(ma)
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Duh. Pelican's catalog says you need 24 rocker arms. I wasn't thinking...Didn't know when Porsche made 4-valve heads?
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Scott Kinder kindersport @ gmail.com |
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Irrationally exuberant
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Are you saying I don't have to say a prayer to the P-gods before opening my toolbox? Next you'll be saying I don't need to pray towards Zuffenhausen every morning on my little P-carpet. You shoud keep your heretical views to yourself. ![]() ![]() -Chris
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'80 911 Nogaro blue Phoenix! '07 BMW 328i 245K miles! http://members.rennlist.org/messinwith911s/ |
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Air Medal or two
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At least you have a seince of hummor too crissbennitt
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D troop 3/5 Air Cav,( Bastard CAV) and 162 Assult Helicopter Co- (Vultures) South of Saigon, U Minh Forest, Delta, and all parts in between |
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FWIW....... I was at a Porsche recycler place the other day looking thru the rocker arm pile. I looked for about 15 minutes at maybe 100 or so rocker arms. I didnt see one rocker I would say was useable as is.
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John Dougherty Dougherty Racing Cams |
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Irrationally exuberant
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I emailed Competition Engineering today and this is what they said:
Quote:
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'80 911 Nogaro blue Phoenix! '07 BMW 328i 245K miles! http://members.rennlist.org/messinwith911s/ |
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I sent my 3.0 rocker arms to Walt at C.E. for re & re'ing.
They came back as good as new, for way less money than new!
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'81 SC Coupe "Blue Bomber" "Keep your eyes on the road, and your hands upon the wheel."- J.D.M. |
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