I'm looking for some advice on the rebuild of my LS3. It has 51k miles, the last few thousand miles with a TSP stage 2 cam. Changing the oil this spring, it seemed as though someone pulled a prank on me by dumping glitter into my oil (disregard large specs in oil - just a dirty oil pan).




I thought it may have been due some horrible wear to the CHE bronze trunion bearings, but they look good to me.

The oil pressure was relatively low on this motor when I bought the car a few years ago, something I should have paid more attention to. But lately it seemed to get worse: ~19 psi hot idle, and peak pressure at close to 7k was a max of 50, but normally 45 or so. Engine ran great, some piston slap when cold, but otherwise very quiet without any odd noises.

So I tore the motor apart to assess the damage. Seems it may have just been the cam bearings? They look rough, and feel rough on the top, but I was expecting something worse.







To the best of my ability I measured the front cam bearing to journal clearance and came up with .0037", right at the end of tolerance. The oil pump looked fine, but the larger cam clearances plus a possibly worn oil pump may have been the culprit here on my low oil pressure?

Either way, I now have to decide how far to go with this rebuild. The bores look pretty good, and again to the best of my ability, seem to be well within tolerance. Piston skirts don't look to great though.





Would you guys be able to assist in helping me decide what route to go?
This is a 100% street driven car, going fast at times but otherwise just making cool noises. I'm at 460 rwhp currently with stock heads (new valve springs of course), and it's more than fast enough. I do not plan to ever add boost or nitrous.

The options I see:

1. Slap it back together (~$400?)2. Hone to 4.070 (5 thousands over) and install new pistons (~$1,200?)3. New rods as well (~$1,600?)4. 416 Stroker kit (~$2,600?)Anything I'm missing?
I overthink everything, and I'm driving myself crazy right now trying to decide what to do. I don't have a shop in town that can guide me along - especially considering other than the machine work, I'll be doing everything myself. I also don't want to drop $6,000 on a short block.

Thanks!

 

What do the cam and lifters look like?

 

Would start by pulling some rings to check the gaps on them to the cylinders, If gap is not too bad, then bottom end looks fine still, and would just replace the bearings

As for block, cam bearing need to be pulled and replaced, and would check cam to see if it can be polished, or it if needs to be replaced.
Also check lifters and channels in the block for them, and while you have the heads in hand, pull the valve springs to replace them and the seals, and check stems to guides tolerances, as well as making sure that the trunions are not coming apart as well.. Also, since you have crap in the motor, its in the oil lines and cooler as well, so all that has to be replaced too.
Bluntly, guys will blow up a motor, send all kinds of crap through the oil lines and cooler to embed in them, try to reuse such, only to end up with that debris making it way back to the new motor, to stick a oil pump relief valve open dam near right away.

So really, short of the cam/cam bearing and finding the lower oil pressure problem, motor looks like it only needs a refreshing instead.

 

Thanks guys! Cam and lifters look great. I went with Johnson 2110 lifters when I did the cam, which I know can possibly cause a slight drop in oil pressure. Some light scoring in some lifter bores, which I will have inspected at the machine shop (or if I buy a smaller size bore gauge).

I didn't have the oil cooler installed since the cam swap (no racing, and wanted a quicker warmup of the oil), but I may swap my radiator for one that has an end tank cooler. So no junk to worry about there.

So that piston wear doesn't seem too bad in terms of reinstalling them?

 

The first thing that popped in my mind with that wear pattern, was a balancer issue that could possibly even been a problem before the cam install.

It's important to determine the cause before a rebuild, so you don't repeat the problem.

 

Do you mean the wear pattern on the main bearings due to a crank balancer issue? The main bearings didn't look too bad other than some light scoring, but there is one wear pattern on all of the bearings as shown here:

 

Yes and the cam bearings too, since oscillations can affect the cam through the chain which has a tensioner.

 

Personally, I'd be very wary of putting that thing back together without having a pro check it out. You can't have that crap circulating throughout your engine very long without doing damage. You have it taken down this far, damn, do it right or you'll be doing it again. The fact that your oil looks like a glitter covered stripper took a bath in it, and your filter looks full of stripper glitter too would have me more than a little concerned. Not that I think anything's wrong with strippers. After all, they need the cash to get through med school.

 

I checked the lifter bores tonight and they are all within spec, phew. I checked the ring gaps just on cylinder #1 and they are just out of service spec.

Is there any place to get a set of hypereutectic pistons? All I can find are forged, and the cheapest is around $600.

 

www.Rockauto.com Still a little pricey at nearly 53 bucks each including rings.

 

I completely forgot about Rock Auto, thanks! It looks like they really only have standard bore in hypereutectic (other sizes are much too large), so that is an option if I would be able to have a cleanup hone done.

I'm still doing more research today :-/