rosseich

I have an original '72 LT1 coupe with about 30k miles. The engine was completely rebuilt about 10k miles ago. Since the rebuild, it consumes about a quart of oil every 500 miles. Several years ago I owned a '70 Z28 with an original LT1 and recall it used some oil as well.

What have other LT1 owners experienced?

Thanks!

LenWoodruff

I had this same problem with my Rebuilt L82. Turns out the valve guides were not done correctly. I would look there 1st.

My solution was to have PTFE valve seals put in place. But that means you have to pull the heads and have the guides cut to fit them.

CheezMoe

I dont have a LT-1 but plenty of experience with oil burners. @ 1qt/500 miles my guess is there is a ring seat issue.

1. Any Smoke Visible, when starting, idling or accelerating?
2. Can you smell oil burning?
3. Have you checked plugs to look for suspect cylinders?
4. Intake Leak?

A Leak down test may be in order! Good Luck!

73racevette

What kind of rings did you use in the rebuild? If you used Chrome rings, they take a while and need some abuse to seat.


Other rings are easier, but if you have not run it hard for a bit you might try that to see if you can get them to seat. If after running hard for a while, it is still using oil, you have other issues. Might be valve guides, but might also be the finish on your cylinders is a bit too rough.

drwet

Lots of possibilities, but don't overlook the finish on the cylinder walls. I had an engine that was rebuilt by a local shop and they simply left the walls too rough. Its kind of an old school approach where the rough surface is supposed to help the rings seat. Modern rings don't really need that and cylinder finishes should be smoother now than they used to be. That engine of mine would burn a quart about every 1000 miles. Not so bad I couldn't live with it, but not good either.

zwede

Indications that ring seal is bad:

• Oil turns black after only a few hundred miles.
• Stick an endoscope (cheap USB inspection camera works great) through spark plug hole and take a pic of the top of the pistons. If the center of piston has soot/black stuff and edges are clean it's likely oil is making it past the rings.

BROKEN RODS

I would do a leak down test @ TDC that would give you an idea if have ring seal or not. I have seen new builds with 400 miles on them with up to 40% leak down numbers, Because of poor cylinder prep and no plate hone.

derekderek

I think a forged piston will always passed a little bit more oil than a cast piston. There's more distance between the piston and the bore.

Boswell

Experienced oil burning after my build. Heads had been shaved. Block was decked. It cause the intake to not seal correctly along the bottom edge where it mated to the heads. Was pulling oil into the intake runners. About a quart every 500 miles. I had the intake machined to change back to correct angle also use good gaskets. Problem solved. Did compression check first to verify cylinders where not the issue. Not saying this is your problem however a possibility.
Norm

jb78L-82

Some interesting comments. A few of my own thoughts:

1. Just about all brand new L-82's in the late 70's would routinely use a qt every 500 miles from new...all forged bottom end....GM at the time stated normal consumption

2. The rebuild of my OEM L-82 in 2014 with JE forged racing pistons/rings and zero oil consumption.

3. No plate hone/decking of the OEM L-82 block during the rebuild...zero oil consumption, no leaks of any sort...

Some items to think about...........