Curious that you lost #7 lobe on both cams. The GM motors oil from the bottom up, and the back forward. But..... With no mechanical reason cropping it's head,,,,,,,, read this with regards to ZDDP (the soluable zinc molecules in the oil additive package and be aware Rotella and Chevron Delo just fell under the same EPA knife as every other 'over the road' oil and now has DRAMATICALLY reduced ZDDP levels)
Quote:
Directly from the Hot Rod article, June 2006, When Good Cams Go Bad:
SH API oil rating 1996
zinc = 0.130%, 1130ppm (parts per million)
phosphorous = 0.120%, 1120ppm
SJ API oil rating 2001
SL API oil rating 2004
zinc = 0.110%, 1100ppm
phosphorous = 0.100%, 1000ppm
SM API oil rating 2005
zinc = 0.087%, 870ppm
phosphorous = 0.080%, 800ppm
Cosworth Racing Oil
zinc = 0.125%, 1250ppm
phosphorous = 0.115%, 1150ppm
Shell Rotella T
zinc = 0.140%, 1400ppm
phosphorous = 0.130%, 1300ppm
Pennzoil 25W-50 Racing Oil
zinc = 0.196%, 1960ppm
phosphorous = 0.180%, 1800ppm
Quaker State Q Racing Synthetic
zinc = 0.200%, 2000ppm
phosphorous = 0.180%, 1800ppm
Obviously, the 4 oils above do not have an API rating for newer engines.
Their rating would be SH or SG. Pennzoil Racing is SG. Rotella is SH/SJ.
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That was in 06, you ought to see where the levels are now. Take a look at your bottles of Castrol and I'll bet a dollar to a donut they are SM rated. The only way I have found to get a flat tappet cam to survive the breakin,,,
1. remove the inner springs of dual spring packages.
2. The GM EOS is almost impossible to find these days, so the only alternative is to dump $10 a quart off road racing oil like Royal Purple XRP (my preferance) Kendal racing oil, Shaffers etc. Not the CRAP they sell in the local parts houses that has the API sunburst, the OFF ROAD oils with the additive packages to support the extreme pressures of a flat tappet cam.
3. IF you can find Gm EOS that's a big plus, but in lieu of OES, I have a couple of cases of old OLD blue label STP oil treatment. Lay a ribbon of that thick honey crap down the lifter valley so it coats the cam before dropping the lifters inthe bores, then finish off the cam across the top of the lifters so the honey flows into the oil drainback holes in the block.
BTW, this is all IN ADDITION TO the heavy cam lube all the cam manufacturets supply,, it ain't enough! Finally, your going to be rolling the motor over to adjust the valves, to install the convertor bolts, and the last thing you want is to wipe the breakin lube film off before you get to startup and breakin. Get timing set to 10 or so degrees, make sure the float bowls are full of fuel, charge the battery, put a big fan in front of the truck to supply fresh air at the radiator, get a bug sprayer to give the radiator a nice mist every few minutes, Be PREPARED to start up and do the 20 minute cam breakin at 2000-2500 rpm and DON'T Fail. If you have a major problem like a oil or water leak, shut the motor down, fix the problem and get back to RPM and the breakin.
As soon as you have the 20-25 minutes at 2500rpm, shut it down, let the motor cool to stone cold, drain the oil, pull the filter , cut it open and check for debris. Anything in the filter is being circulated through the motor. "SOME" machining dust and fine particles are 'normal' if you didn't wash and brush the motor sanitary clean before assembly (to which I say SHAME on you). If you DID clean the casting corectly,,, you might see a flake here and there, and is more 'normal' . If you cleaned the block correctly, anything more than a 'flake' is the cam going away and you might as well stop and pull the motor back apart before you trash the crank and every other machined surface.
Non API starburst oil is surely not cheap, but compared to new cams, lifters and fresh bearings every time the cam wipes a lobe,, it becomes pretty reasonable.
My breakin ritual of a flat tappet motor....
20 minute breakin then dump the oil and filter,
500 miles (10 hours)MAXIMUM and do NOT let the motor idle under 1000rpm with no less than 35-40psi of oil pressure,,,and again dump the oil and filter
Then again at 1500 miles and at 3000 miles you go to a normal 3000 mile schedule.
Excessive??? maybe, but I have never (let me say that again) 'NEVER' lost a flat tappet lobe on a motor I built. In that same breath I have to say that I quit building flat tappet motors about 2 years ago too. You can figure about $1000 to go to a roller package with a good set of Morel hydraulic roller lifters (w/ springs and correct length pushrods) It's $'s well spent IMO,,, but, just my 2cents