Cam bearing let down

-
Sorry for posting this here and reviving an old thread, but I tried messaging @nm9stheham and @yellow rose but couldn't upload pictures in that private message!
I'm rebuilding my 360 following KrazyKuda's diy, and the cam bearings worried me. You two seem to have experience with knowing when to leave them alone. Could you please give me your opinions? This will be a pretty hot street stomper with ~500hp (stock stroke), if that matters for your judgement. My main concern is, if the babbitt flakes some more... where does it go? On a nice tour of all my other bearings, scratching everything in the way? Thank you in advance!

That's #5, against the back of the block, looks pretty good:
#5.jpg


That's #4, the scariest:
#4.jpg


That's #3, pretty good except for that one very little piece of babbitt missing:
#3.jpg


That's #2... the second scariest:
#2.jpg


That's a view of the top of #1. No chunks missing, but the oil groove is suspiciously shallower on top.. so much that it's noticeable in the picture:
#1 (top of bearing).jpg


And finally, bottom view of #1. No worries with this one...
#1 (bottom of bearing).jpg
 
Looks like fatigue damage similar to what I found in my 340. I had used standard 1484M bearings. This time I bought high performance SH875S Clevite 77 cam bearings.
IMG_5400[1]_1280x960.JPG
 
Apparently the babbit gets brittle with aging and flakes out. If you are going 500 HP, then your valve spring pressures are going up, maybe waaaay up, and that is going to put higher forces back into these bearings. I can't imagine not doing replacing them for this level of performance.

The babbit flakes ought to just work outwards and find their way into the pan... unless they work their way down a web and somehow get into a main bearing.... but that seems unlikley.

Coincidentally, the #1 and #5 positions see the least amount of the spring pressure forces, and #'s 2, 3 and 4 see the most.
 
You must log in or register to reply here.
-

Back
Top