Getting 1800 miles/qt on 93 lt1 383. Bulider wants to do leakdown. No smoke blue or black out the back. If rings are glazed what would that do? Oil loss. Plugs are dry. thanks

 

Cylinder wall/ ring glazing reduces the sealing efficiency......AKA blow by. Your engine if not burning oil it may be pumping it into the vacuum lines......brake booster......vapor canisters...stuff like that. Proper rings, piston clearance, and cylinder wall cross hatch are needed for long term engine performance. A engine vacuum check and or compression check will tell the engine builder a lot.

You can do a quick check for positive crank/bottom end pressure by pulling the engine oil dipstick out and sticking a piece of tissue paper (not small enough to get sucked in there in case there is a vacuum) on and barely into the dipstick hole then reving the engine at various speeds. If the tissue paper blows out while testing you have significant blow-by issues.

Good Luck!

 

What would cause this glazing?

 

New rings have to wear into the cylinder walls to seat properly. An improperly prepared cylinder wall can prevent the rings from ever fully seating. A polished/improperly cross-hatched cylinder wall seems to be what your looking at from my perspective.

 

So the builder would take responsibility? So take it to be rebuilt by someone else?

 

Mistakes happen.....Did you get some type of waranty with the build?
If you want take the car somewhere else and get a second opinion as to what is going on with it before you tear it back down.

 

If that is the worst the builder does, don't risk taking it somewhere else and risk causing more damage. If it was indeed his fault, he should man up and replace it for free.

 

Leakdown and compression tests aren't really going to show you the cause of most oil consumption issues unless there is significant cylinder damage.

Cross-hatch, glazing, oil control rings, valve seals (major oil consumption items) aren't going to show up as a red flag in leakdown or compression.

Compression tests obviously tell you if all of the cylinders are sealing properly and are balanced. Compression tests indicate if you have a burnt valve, blown gasket or something causing a loss of compression. They also indicate the overall health of an engine. However, when changing cams the compresson results seen when cranking can vary significantly from the factory specification due to valve timing events.

Leakdown traces the loss of compression path: intake (heard through t-body or carb), exhaust (heard through exhaust) or significant ring wear (heard through PCV). Leakdown can also give an indication of overall health via sealing capability of the cylinders.

High oil consumption can even be cause by running the motor too rich or using an oil that is too light of a weight or incorrect spec. for the application.

I would let the builder do the checks he wants to do but if he says leakdown in good so it can't be his fault...see my comments above.

 

If the rings didnt seat-is that my responibility because i didnt break it in appropriately-I did what they told me to or the rings didnt seat because the cylinder walls were not preped correctly.

 

If you did exactly what they told you and the motor never over-heated or ran excessively rich, I'd be having a discussion with the engine builder about him covering it.

There's a lot of details left out of your post so to offer an opinion regarding who is at fault is a moot point. I believe it needs to be diagnosed before anything. One question - how many miles since the rebuild?

I have seen rings either damaged or failing to seat properly from over-heating, over-revving, over-fueling and poor cross-hatch or improper cylinder finish for the brand of ring being used - other reasons also exist but are less common.

Typically, on a liquid cooled engine, if the vehicle is set up properly, driven properly during break-in and it's within a reasonable amount of time, the builder should step-up.

If you beat it to death while breaking-it in because the new motor was so much fun, you're on the hook.

 

Well i initially started with 1 1993 lt1 stock-this is in a 79 corvette-was getting 500 miles per quart- moved here to texas everyone told me to rebuild-rings were shot. so i rebuilt to 383 hot cam 1.6rr comp headers, forged pistons, ported heads and builder put Total seal rings-gapless-I got 300 miles per quart oil-Showed builder all the stuff from internet about gapless and builder put new rings standard moly. now I am at 1800 and hearing this is not acceptable. Notes of interest:

Broke in engone with 30 SAE oil as directed normal driving.
I never beat on the engine.
At 1800 miles i told builder what I was getting and he said I should be getting more-said to continue to drive.
I did not know but inthe injectors were 20# and I thought they were stock.

Changed to 30# as directed by Chip maker and his chip. Car ran better.
Been driving 1.5 years and had it dynoed-dyno man sid he could complete dyno because it was detonating-Changed back to First chip and and put ford blue injectors-when changing the injector i found out the fuel regulator was shot-fuel going into intake.
Replaced regulator an back to dyno-260hp 300tq- poor for 383.Dyno man said no blow by out back. Air fuel was a little lean

He said it wasnt detonating and to stay with this chip put 10/40 oil and break in oil. He stated to try to reseat rings. At 500 miles I am still loosing oil. Builder want to do leak down -possibly valve seat?

 

If there was blowby would the plugs be wet?

 

What is your max rpms?

GM determined that the LT4, with a slightly higher redline than the LT1, needed positive twist rings to prevent blowby at the higher rpms.
And, it would seem, the LT1 got along fine without positive twist rings.

Tom Piper

 

I hardly ever go above 3-3.5 Its an auto trans. In park can easily go to 7K.

 

Here's a man that knows what he's talking about.
A leakdown, at best will show you the integrity of the valves and seats, their ability to seal, and the same for the top ring. THATS ALL.
FWIW, 1800 miles to a quart isnt all that bad. It could be coming from several sources. A couple small leaks, some oil consumption, etc. could easily combine to loose that much over that period of time.

 

What kind of mileage would you expect if the rings didnt seat? I can deal with valve seats but if it is the rings then i will have to pull the engine. I hope they find something rather than an issue they cannot find.

 

Pull your plugs. If your rings aren't seated, you'll have plugs with oil deposits on them, and it should smoke pretty good.
By the sounds of it, what you've posted, it doesn't sound like rings that haven't seated.

 

If the rings didn't seat, combustion pressure will most likely blow out of the cylinder into the crankcase and overwhelm the PVC system before it will suck oil into the combustion chamber.

Engines with excessive blowby typically smoke on acceleration because of excessive crankcase pressure. In many cases the plugs will look ok - especially in computer controlled vehicles.

A bad valve seal or leaky valve guide would be a much more likely candidate for oil fouled plugs - again assuming there isn't significant damage tot he cylinder walls or ring package.

Your comment on parasitic loss due to leaks is great and is often forgot about.

I too would agree that using one quart per 1800 miles and everything checks out that I wouldn't be running to pull it apart just yet.

 

Plugs are not fouled. Car is in shop today.

 

leakdown results- 10%, 12%, 8%, 12%, 20%,10%, 14% said he could not get to last plug with removing header.

Would these results be responsible for 1800/quart?

He says its good and not to place Valve stem seals-but i am almost positive there are positive valve stems with o-rings on there-could these go bad?

Help please?