Juicedh22

iTrader: (6)

I'm having a machine shop do a rebuild of my ls3 block for a 416 stroker. The block has been hot tanked a couple times (most recently after grinding the rod bolt clearance at the bottom of the bore). I went to test fit the camshaft (comp cams, new cam) and not only was it very tight just to install, it also was nearly impossible to spin.

I took the cam back out, measured to make sure it was still in spec (2.1657 was largest). Then set a bore gauge to measure clearance from 2.166, and I was getting 0.002- 0.0025 clearance measured. I also used a bearing scrapper to clean the bearings, and a bit of scotch-brite to smooth it out. I used some light oil and re-installed the cam, and it goes in easy and spins now, but with a bit of resistance. It is also worth noting the rest of the block is bare, the mains are not in, which I hear makes a difference?

As I was researching I noticed some comments from SBC guys that when you hot tank you 'have' to replace the cam bearings? Is this true? and why? Could that be the cause for my bearing tightness?

S10xGN

iTrader: (11)

The bearings need to come out before it goes in the tank. That's the only way you'll get the oil galleys clean. Not sure what the aluminum cleaning solution will do to bearings, the stronger stuff they use on iron blocks will destroy them...

Juicedh22

iTrader: (6)

Why would it block the oil galley? the hole in the cam bearing is bigger than the oil galley hole? I figure the solvents used today are much less caustic than the solvents of the 80s when it might have eaten material...

Faststudy101

Cam bearings are so cheap, why worry about it? Just have the machine shop knock the old ones out and put new ones in.

Juicedh22

iTrader: (6)

Because I'm doing the work, and proper cam bearing install is critical, and not something I want do mess up, or be afraid I did. The cam bearings that are in it have less than 9k miles on them.

On subject, talked with several shops/experts today... Sounds like its no problem.

I polished the crank journals down to nominal size, finished cleaning up the bearings. Put it back in with the main caps torqued on and I can spin it with the tab. It has resistance, but it spins.

S10xGN

iTrader: (11)

You're misunderstanding things. The bearings are removed because there will be crud inside the oil galley behind them that will remain there if they are not removed before the block is cleaned.