Some may have followed my posts a bit but here is a summary, sorry it got so long, but the back story I think is important to get the whole picture. I just broke in the cam Saturday.
I built this motor (302 flat tappet, .040 over). The machine work was in my opinion excellent. I followed all the rules and now after tear down, I would not have done anything different knowing only what I know.
The motor went together “perfect”, meaning no red flags or concerns (once I got replacements for a couple defective parts (lifter and push rod). Cam and crank spun easily, primed the motor before firing. Got oil evenly at all rockers and I primed in 8 crank positions.
I broke in the cam for 30 minutes and did not hear anything strange, maybe some tapping here and there but no squealing, etc. After break in I changed the oil and it looked really good to me (a few shiny specs but that seems normal from what I have read). Changed the water with 50/50 coolant, and the water looked good (no oil). There was not a single leak on the motor.
The next day I installed the Sniper EFI and Hyperspark distributor. (broke in with carb and mech dizzy). The motor fired immediately and I ran for maybe 10 minutes while I was figuring out the idle. It was idling 1250 RPM and I got it down near 800 for now. Now here is where I found a big problem. The Sniper RPM and my external tach RPM were way off, like 50% (Sniper 1250, Tach = 2500 RPM). OK that’s not good. I look at the external tach and realize that the switch somehow got clicked over to 4 cylinder when I was mounting it. I was so preoccupied with monitoring everything in break-in, that I just adjusted to that. I have not had a “muscle car” in 30 years so I did not even consider the RPM was not high enough from the sound of it. I had a lot on my mind to say the least at that point. Live and learn. So that motor has 40 minutes of run time.
Oil was clean but I know
the cam was not broken in properly. I decide to cut my losses and replace the cam and lifters now and not later as if it wipes lobes and fills the motor with metal.
So I tear down (lifters look great but I press on), pull the motor and get the cam retainer plate off. It looks bad before i even pull the cam out. There is metal between the cam journal #1 and the bearing/block (this is a huge surprise as this is NOT why I was tearing down). Like the bottom “filled with metal”. I know I recessed that bearing, so did it move and squish? No way. So now I can’t get the cam out. I was able to turn it but it was tight and then could not budge it. Pull the flex plate, knock out the cam plug and able to tap out the cam shaft. #1 bearing totally wiped out. I peer into the block and ALL 5 bearings are totally wiped out. See pics. The oiling holes on all bearings are still aligned properly but basically plugged with bearing metal now. When I pushed the cam out, each bearing sheared off a sliver of bearing. It looks as though the bearing melted and redeposited metal and also squeezed some out the side. Fortunately, before I pulled the motor I drained the oil and again it looked clean. I think I caught this just in time before things really got ugly (not that this is not ugly enough). The lifters and cam lobes look great by the way
(lifters have circular burnish type marks which is how I understand they break in). Of course if I rebuild this, new cam and lifters for sure. Even the cam journals look good, as the bearings sacrificed themselves.
I remove the crankshaft and the main and rod bearings all have some spots on the bearings that are the “dull” factory kind of finish and some shiny spots (maybe this is normal). But all the rod and mains had plenty of oil when I took them apart and I think they are fine. No foreign material in there and the surfaces are smooth. The crank journals look perfect.
So I have oil to the crank/rods, I assume still oiling the rockers and no oil or somehow overheating the cam bearings. I could see if it was one bearing but all 5? #1 gets oil direct right after the oil filter and 2,3,4,5 are indirect from the mains. So again, if I destroyed just #1 or a combination of 2,3,4,5 then maybe that tells us something. But all 5 means something different. Maybe too much oil going other places? I have also read that possibly the bearing failed due to high rocker spring pressure. (My E-street heads are only 300 PSI or so springs, so nothing of the ordinary. Cam bearings are Dura Bond F-18 bearings. All bearings failed at the bottom and “moved” molten bearing metal up clockwise.
HELP! If I figure out root cause, I rebuild this motor. If not I'll get a crate short block. I just can’t think of a reason for no oiling to these bearings.
Cam Bearing #1.JPG
Cam Bearings 2-5.JPG
Rod and Mains post break in.JPG
Rod and Mains post break in1 .JPG