OvalHunter

I'm in the middle of a head/cam swap and have a couple of issues. First of all I found all of my missing oil --- neatly deposited in/on the combustion chamber/piston head. The PCV dumping system is working well <img border="0" title="" alt="[Mad]" src="gr_images/icons/mad.gif" /> Looks like a catch can is in order.This would explain the "sudden" appearance of piston slap and also explains why GM uses top engine cleaner soaked on the pistons to mitigate.

Worse yet is the condition of the cam bearings. the babbit is worn off the drivers quadrant and copper is showing. Makes me wonder the condition of all of the other babbit bearings in the engine.

My gut tells me to pull the engine, replace the cam bearings and have a look at the rest (ARP rod bolts while I'm in there <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" /> ). I've only got 17K on it and I can't beleive it. I've seen motors with 10X that and the bearings still looked new. Religious oil changes don't appeared to have helped.( maybe the 3K on dino oil at break in?)
The factory timing chain was a real POS too. It had a good 1/4" of slap in it. You could easily rotate the cam back and forth.

What do you guys think? I have to pull the tranny to upgrade the clutch anyway - there isn't much left before I have the short block out.

Please offer your perspective. I'd like to have a couple of years before I see these guts again!

strokedls1

iTrader: (1)

I would pull the engine and get everything checked while it's apart. Great time to upgrade some parts, maybe even some diamond forged pistons. I had 34,000 on my block and the bearings looked to be in pretty good shape. Those stock chains do suck. Lots of play to mess up the cam timing.

jmX

The deposits on the pistons is pretty common. The timing chain is always slack like that, a brand new one will be the exact same.

Dunno about the bearings.

Vettepartz

You posted:
.( maybe the 3K on dino oil at break in?)


I have not heard of this practice before. Am I missing something here?

OvalHunter

I ran regular Valvoline 10W30 for the first 2 oil changes (~ 3000 miles) and then Royal Purple #21 for 1 cycle and Mobil One for the last 3 (6 oil changes in 17,000 miles).
I think many people (including myself) consider synthetic too slippery for quick ring seating on fresh cylinder walls. That was my logic - could be wrong <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />
The oil has never even looked very dirty; however, I have never dissected my filters either.

-Joseph-

iTrader: (12)

I see allot of cam bearings appear to be worn out, I think its mostly the color of the bearing GM uses. I wouldn't worry about them unless you had some oiling pressure issues. You can always measure the #1 cam journal and bearing and see what the oil clearance is if you were worried.

NO CATZZ

iTrader: (10)

Aluminum blocks run a lot more slack in the timing chain(compared to traditional iron blocks) to compinsate for heat expansion. I got a little worried when I did my cam change but when I looked up the specs(something like 5/16 play) I quit worrying.

Also, my pistons and combustion chambers where very caked with carbon. I had the heads cleaned up at a machine shop and just used an air grinder with scotch brite to clean the pistons.

Good luck.

SixPak

3k on break in oil?
I've bought a half dozen new vehicles and never gone that far on a new engine. I might go 50 miles, but no more. the dealers are very resistant to changing oil on a new car, so I've driven from the dealer directly to the speedy lube joint on my last two new car purchases.
I personally see no reason for leaving oil in a new engine that long. dealers and 'engineers' will say the rings need to seat. well, if they weren't seated, wouldn't the engine be smoking or running like crap? after you rebuild an engine, do you leave the oil in it for 3k? not me. every engine I've rebuilt has gotten an oil change as soon as I'm satisfied that the rings are seated, it has no knocks, and has come up to normal operating temp. in other words, it never leaves the shop with 'break-in oil' in the crankcase. I like to see what kind of junk comes out of the crankcase after a fresh rebuild. it seems no matter how careful you are, you always find something, metal chips, sand, a loose tooth. so how can anyone think an auto manufactuar could do any better? is there even a remote possibility any sand from the casting process is in there, or metal shavings from machining?
oh, I forgot. they put an oil filter on there, just in case. <img border="0" title="" alt="[Roll Eyes]" src="images/icons/rolleyes.gif" />

OvalHunter

I changed the oil as soon as I got home as well - I have religion.(The car was driven to my dealership for delivery and had 230 miles on it) I then ran Valvoline 10W30 for two intervals of arouind 1500 mile each. At around 3500 miles I changed to Royal Purple #21. About 2700 miles later I switched to Mobile One 10W30. I have done three oil changes with that - which brought me up to my current 17,xxx miles - two summers worth of driving and nine blasts down the track this past year. A new AC filter each time. (I kept all of the receipts just in case I would have warranty issues in the first year or two).
At this point I'm not worried about warranty - that went out the window with this winter's mods <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" /> .
It just seemed to me to be a fairly diligent effort at keeping the oil changed and I was just a little suprised to see through the babbit on such a fresh motor.
My current thinking is to live with it and go in next year and update the rest of the internals - no dough left this winter <img border="0" title="" alt="[Frown]" src="gr_sad.gif" />

NHRATA01

iTrader: (10)

2 of my cam bearings were showing copper at 10K too...

Here's a couple pics (if i can get this to work), sorry for the quality being a little fuzzy.

http://community.webshots.com/photo/...62582579LHjqMy

http://community.webshots.com/photo/...62582608ckvqWq

Ended up replacing them, but some people seem to be saying its not a big issue <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />

robertbartsch

I've seen copper showing through on transmission bearings before. It is no big deal, but measure clearance if you are worried...

DriveATransAm

i wouldnt worry too much about it. when i did my cam swap i had the same wear- and mine was done at 8K miles. break in- easy the first 100, then drove it hard to 500 and that was the first oil change. i was at the track often so i replaced it again with dino at like 1200 or around there. i ran dino up to about 3K i think....then i started using m1 10-30. i just recently noticed more piston slap than before. i think i may need a catch can. i emailed the picture i took of the bearings to a sponsor and he said thats pretty normal of the ls1. i just let the car warm up good before i start driving it- thinking the lack of oil on cold startup, then driving it right away might have contributed to the wear.

C_Williams

I have a new block that shows the copper in some areas. If that means anthing, you are OK.

However, if you yank it out and need the ARP bolts, let me know..I have a set brand and reasonably priced.