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Technical SBC eats cams

Discussion in 'Traditional Hot Rods' started by AGELE55, May 29, 2021.

  1. AGELE55
    Joined: Jan 4, 2018
    Posts: 398

    AGELE55
    Member

    So an SBC that served me well for 37 years has decided to devour cams. I had replaced the cam as part of an engine refresh with new lifters and cam. The cam lasted less than 1000 miles and ate a single lobe down to the nub. I used assembly lube, and did a proper break in, so wrote it off to a bad cam (fingers crossed).
    I flushed the oil pan, and valley and purged the system by spinning the pump with a drill and fresh oil. Then replaced that oil with fresh oil and installed another cam. Swapped oil at 500 miles. At less than 1000 miles, it ate 9 of 16 lobes. Aaaaaaarrrrgg.
    I ordered a crate engine for it cuz I'm tired of dicking around and want to drive it. It's earned a new engine after being a loyal 37 year driver.
    Question: What the frick is going on? I'm thinking either:
    A). The new oils have no zinc, which I'm reading is necessary during break in.... OR ...
    B). I also replaced the oil pump with the first cam. Maybe I ordered a high flow and its keeping the oil top and emptying the pan?
    I'm not seeing any other damage to the engine. Cylinder walls look good. I have not pulled the caps to inspect the bearings.

    FYI- I broke in another engine during this time with regular oil and have zero issues.
    I'd like to save this engine, but it's got me spooked.
    Thoughts?
     
  2. Budget36
    Joined: Nov 29, 2014
    Posts: 7,569

    Budget36
    Member

    I think the prudent thing to do would be to flush out all the oil galleys, in effect take the entire engine apart.

    Next thought is maybe too much spring pressure for break in?
     
  3. Moriarity
    Joined: Apr 11, 2001
    Posts: 22,293

    Moriarity
    SUPER MODERATOR
    Staff Member

    did you use oil that has zinc in it? valvoline racing oil has zinc and there are others. If you used normal oil then you did it to yourself. what oil did you use??
     
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  4. AGELE55
    Joined: Jan 4, 2018
    Posts: 398

    AGELE55
    Member

    Regular 10w30.... maybe a self inflicted wound..
     
    Nicholas Coe and sidewayzz69 like this.

  5. Moriarity
    Joined: Apr 11, 2001
    Posts: 22,293

    Moriarity
    SUPER MODERATOR
    Staff Member

    yes it was...... man, I thought everyone knew that by now. you better change the oil in your new engine immediately if it isn't already too late. and some may disagree with me but I run high zinc oil in my old cars all the time, not just for break in
     
  6. squirrel
    Joined: Sep 23, 2004
    Posts: 50,297

    squirrel
    Member

    New oils have zinc in them. They don't have quite as much as old oils.

    Taking the engine completely apart, and removing ALL the metal, is necessary after a cam failure.

    Another way to deal with it is to go to a roller cam.
     
  7. You answered your own question. It's the lack of Zinc. I use GM EOS "engine oil suppliment" or Penngrade racing oil which is the old Kendal racing oil. Valvoline VR1 Racing oil is good too
     
  8. 1971BB427
    Joined: Mar 6, 2010
    Posts: 7,094

    1971BB427
    Member
    from Oregon

    Cam failures or any failure that puts fine metal into the oiling system eats up not just cams, but also bearings. I'd never just put a new cam in and hope the rest was OK. It needs to be hot tanked, and flushed with oil galley plugs removed.
    And the engine oil has to be of a high zinc content for a flat tappet cam to survive. Valvoline Racing VR-1 is what I use as it's still got a high zinc content. You can add ZDDP to any oil also to increase the zinc content. Be sure to add a bottle to your new engine if it's also a flat tappet cam.
    I finally broke down and built my last SBC with a roller cam since it is a factory roller motor setup anyway.
     
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  9. cj92345
    Joined: Jun 17, 2009
    Posts: 161

    cj92345
    Member
    from so-cal

    One lope shouldn’t warrant a complete disassemble imo, but yeah zinc oil for sure
     
  10. Joe Gibbs break in oil for flat tapped motors. Is what I use and never had any problems.Frank
     
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  11. Belvedere1
    Joined: Aug 29, 2020
    Posts: 8

    Belvedere1
    Member
    from 85050

    Check to see if the lifters spin in the bores as you roll the cam through before you finish the final assembly. If one isnt spinning then place it another spot until they are all rotating.
     
  12. AGELE55
    Joined: Jan 4, 2018
    Posts: 398

    AGELE55
    Member

     
  13. AGELE55
    Joined: Jan 4, 2018
    Posts: 398

    AGELE55
    Member

    This engine will now go to the back corner for safe keeping until a future teardown, boil out, and rebuild.
    Ignorance can be cured with knowledge, but stupidity goes right to the bone.
     
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  14. 2OLD2FAST
    Joined: Feb 3, 2010
    Posts: 3,641

    2OLD2FAST
    Member
    from illinois

    Glad you're not doing my engine work ..
     
  15. look on utube ellison machine your engine guy . It is not only you having this problem . I was thinking maybe I am getting to old to build an engine .
     
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  16. Deuces
    Joined: Nov 3, 2009
    Posts: 21,627

    Deuces
    Member
    from Michigan

    Like Squirrel sez.... Go roller and forget about it!....:cool::rolleyes::cool::D
     
    AHotRod likes this.
  17. 2OLD2FAST
    Joined: Feb 3, 2010
    Posts: 3,641

    2OLD2FAST
    Member
    from illinois

    Are you financing ?
     
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  18. Truckedup
    Joined: Jul 25, 2006
    Posts: 4,280

    Truckedup
    Member

    When I was in HS in the early 60's, the 265 and 283 were known to lose cam lobes at less mileage than other engines.
     
    Elcohaulic likes this.
  19. Blues4U
    Joined: Oct 1, 2015
    Posts: 6,111

    Blues4U
    Member
    from So Cal

    That's not accurate....

    Squirrel is correct, all engine oils have zinc as an anti-wear/anti-oxidant additive. Its true the levels have decreased from previous levels, but the level of zinc in modern engine oils is still as high as it was back when most of the OHV engines we use were new, and the quality of the zinc is vastly improved vs the zinc used back then.

    Careful just dumping aftermarket zinc additive into an engine, unless you have the ability to run effective compatibility tests on your own, and if you did you probably wouldn't be buying engine oil, you'd be blending your own.

    There are engine oils out there with higher levels of zinc, but you have to do some research. An easy way to go is to find some heavy duty diesel engine oil that carries the CJ-4 or earlier API service classification, they will have ~ 1200 - 1400 ppm of high quality zinc. Typically available in 10W-30 or 15W-40 viscosity grades, one of them should work well for you.

    FYI, as I've written about before around here on other threads, the way zinc works is to plate out on the wear surfaces up to a certain thickness, and no more. Higher levels of zinc in the oil DO NOT produce thicker films, the only thing higher levels of zinc accomplish is a sort of reserve capacity; as the film wears off during normal use the remaining zinc in the oil replaces it, and the thickness is maintained at the maximum. If the oil doesn't have sufficient level of zinc over time as the zinc is depleted the engine will experience accelerated wear. If the failure occurs in less than 1000 miles it probably wasn't due to low zinc levels in the oil. One thing higher levels of zinc will do is fight with other surface acting additives, preventing them from doing their job. Lubricant mfgr's spend a fortune developing and licensing engine oils, they are carefully balanced blends of chemicals. Its pretty hard to out do them by mixing up your own blends using aftermarket additives.
     
  20. I still use GM break in additive when I am breaking a cam in. Maybe I have been lucky so far, knock wood.

    I have been told by more then one cam guy that if the cam lives through break in you are normally golden. I usually try to keep good oil in my engines and try to buy good quality cam shafts. I am going to say something that some here will find offensive, but here goes anyway. I buy cam shafts from cam shaft companies, not from oil pump companies or ignition or carburetor companies. I also do not buy ignition or carburetors or oil pumps from cam shaft companies. This is not to be offensive this is just sage advice based on experience.
     
  21. 2OLD2FAST
    Joined: Feb 3, 2010
    Posts: 3,641

    2OLD2FAST
    Member
    from illinois

    Most cam , oil pump , ignition companies are using the " name" of whoever purchased them lately , these days , name brands mean nearly zero / zip/ nada !
     
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  22. jimmy six
    Joined: Mar 21, 2006
    Posts: 10,295

    jimmy six
    ALLIANCE MEMBER

    What’s your rods side clearances? I’ve kept mine .018-.020” to throw more oil at the cam, pistons, and cylinder walls. If I could still get “spit hole” bearing inserts I’d file a gap line in the rod cap for more like the original SBC’s were manufactured in the 50’s-60’s..solid lifter cams gave some gap time for oil too. Your savior today are hydraulic roller cams..
     
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  23. Agree on using the right break-in oil. After that you should be good. As Blues4U stated, modern oils do have anti-wear additives. Yes different chemistries than old oils, but they do have sufficient for a broken in engine. The point about checking lifter rotation is very valid, the lifters must rotate completely and easily in their bores.
    Couple alternatives are the roller cams as suggested. More money, but also able to get more area under the lift curve. So potential for better performance. You can also investigate the lifters with a very small EDM'd hole that feeds oil to the lifter face. That face is lubed mostly by splash oil, so a direct oil feed might be beneficial in your problem engine.
     
    AGELE55 and Deuces like this.
  24. On the SBC use 1:3 ratio rockers for the break in,or lower pressure valve springs.After its broken in change springs,or rockers to what you want to run.If you go crate engine get one with a roller cam,and be done.
     
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  25. Make sure the lifters you use are high quality. Junk from China will ruin a cam fairly quickly.
     
  26. 1971BB427
    Joined: Mar 6, 2010
    Posts: 7,094

    1971BB427
    Member
    from Oregon

    I guess I'm out of touch, but can't say I've seen a camshaft sold by MSD, Mallory, Pertronix, etc. ever? Nor one sold by any oil pump manufacturers? I have seen camshafts sold under Summit, or Jegs, etc., but I'm pretty sure they're having a camshaft company just make them for them?
    I stick with name brand cam makers also, but only because I've never had a chance to buy a Mallory, MSD, Holley, etc. camshaft.
     
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  27. 1971BB427
    Joined: Mar 6, 2010
    Posts: 7,094

    1971BB427
    Member
    from Oregon

    1:3 ratio valve springs? Afraid they'll do more damage than help. If you could even find 1:3 ratio rocker arms the ends wouldn't be centered on the valve stem and would likely damage the end of the valve stem from running off center during breakin. Even 1.6 ratio rockers will require a proper length set of pushrods to correct the rocker angle to center on the valve stem.
     
  28. All the lifter you can buy no matter what name is on them or who sells them come from 2 places both in china .
     
    buick bill likes this.

  29. That's hard to believe, but maybe so....... He can always find NOS GM lifters on the internet......
     
    Deuces likes this.
  30. Moriarity
    Joined: Apr 11, 2001
    Posts: 22,293

    Moriarity
    SUPER MODERATOR
    Staff Member

    I put a cam in my off topic Chevelle last December. I bought the cam and lifters from Isky. Everything went great. I figured that they have been in the business for a long time and they have a quality product....
     

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