Hey guys. I really need some help here. I bought a SBC 350 4 bolt main and rotating assembly from Larry's Performance (big mistake!). It is .040 with hyper-t pistions. I assembled it with a Comp Cams hyd cam, .440 lift, new push rods, and rockers on top of some Indy iron 2.02/ 1.60 64cc reman heads. Performer RPM with a Demon 625 on top. We installed it in my '70 Chevelle with a new TH 350 behind it. It fired right up and ran great. Oil pressure at idle is 30 psi and about 55 psi while cruising at about 2600 rpms. After about 100 miles I noticed what sounded like a loose lifter ticking. I pulled the valve covers and noticed that exhuast on #6 cylinder was very loose. I adjusted it back (took the slack out of it and 1/4 turn preload)and checked all the others. About 20 mile miles and it was ticking again? I inspected it and noticed the rocker nut was much lower than the rest when it was set correctly? Now the 2 lifters in front of it on the driver side were also loosing and oil pressure was down to 5 psi at idle. I pulled the intake and noticed the lifters were sitting too low in their bores. I thought maybe they had an oil suppy problem. I pulled the #6 exhuast lifter and spun the oil pump with a preluber on my drill. The empty lifter bore was flooded with instantly. I thought maybe after all these years of engine building I goofed up and set too much preload on them during assembley. I removed the cam and cleaned the lifter vally with thinner to remove any debris from the pan as it drained. The lifters all looked great except the 3 that had lobes rounded off. They did have a pattern on them that showed the had rotated before the trouble started. The lifter bores were checked and nothing seized or scored. We lubed up and installed a new Crane 282 Energizer cam and lifters. The cam and lifters were lubed exactly as they should be. Fresh oil and filter. We prelubed it with a drill and it read 35 psi and all rockers were getting oil. She fired right up. We did a text book break in like the instructions state. Oil pressure was 65-45 psi during the 25 minutes break in. Changed the oil and filter and fine tuned the carb abd timing and too kit for a spin. The car loved this cam ran great with great oil pressure. I drove it to work Monday, 25 miles round trip. When I got home I noticed a lifter ticking! I pulled the passenger side valve cover and #6 exhuast was loose? I bumped it over and sit the preload again. I then unpluged my ignition and cranked it over while observing the rocker... maybe .010 lift! The lobe is already near gone! Needless to say I was PO'ed and ordered a crate motor from GM, but I still need to know what is wrong with this block? Any ideas? Anyone ever seen this before?  

Did you use a break-in additive when you broke both cams in?

Sounds like you didn't. The problem is, today's oil doesn't have the heavy metals necessary for a proper flat tappet cam break-in. Both Comp and Crane sell the additive you MUST use when breaking in a cam with today's oils to ensure that you get proper camshaft break-in and life.  

Phill,

Thanks for the reply. Both cams were broke in with Rotella 10-40, as suggested by Jeff at Reher-Morrison and in CHP. As for the new additive, I understand the intent of it, but most engine shops (including Reher-Morrison) I have spoke to have told me it is completely un-needed if the cam has been lubed and is broke in correctly. Even the Comp Cams tech line said it was not needed for proper break in. But it is probably cheap insurance. But what are the chances of two cams failing on the same 3 lobes from not running a additive? Probably none. I'm thinking it has to be some thing in the block. I thought maybe a stuck valve might be putting too much pressure on the valve lobe, but the heads were just built by Indy Cylinder Head and they were on the 307 for 5 months before we switched over to a 350 with no problems. And it is lobes from both sides of the motor, so what are the chances again that both head went bad... none. The new crate motor gets here Friday  , this motor will get torn down until I can find the problem. Thanks again. Anyone else got any ideas??????????  

Check your spring pressures and valve spring installed heights.  If the valves springs bind or exert to much pressure it'll be like a lathe tool and round off the cam lobes.  Also check the rocker arms for galling at the tips, It's unlikey it's the block.  

Just an opinion.After losing three flat tappetcams in under 50 1/8 mile passes,I am now a die hard roller cam man.Its actually cheaper power,dollar for dollar.With what I had to pay when I wiped out my mains and rings (and almost pistons),with the metal particles off the cam and lifters,I figure roller puts you ahead of the game on only one rebuild.Not to mention,if you swap cams alot,you get to reuse your lifters.I know the cams run $250+ ,but just think about it.Once you go roller,you get hooked on them.Great torque down low,able to breathe up high to post those big HP numbers,too