Convoy25

iTrader: (3)

before i start i'm just going to say i know there are some exceptions.

so its safe to say that around/a little after 100,000 miles our engines need work/to be rebuilt, things tend to go.

is that the same for LS engines? would i be fine around 100,000+ miles or would i have to plan to rebuild it?

Atilla the Fun

typically, our engines are good to 150,000 miles. At that point, they need a full rebuild. With the LSx, just keep driving to 300,000 miles.
Bore wear isn't much of an issue even then, unless you stuck a carburetor on it. Valves still wear, the rings lose tension, timing chain, et cetera.

Convoy25

iTrader: (3)

awesome thanks!

305sbc

iTrader: (3)

There are more factors involved than just miles driven.
Age, heat, driving style, maintenance intervals (oil changes), modifications, and fuel additives are just some of the factors that come into play independent of miles driven.

Alternate factors like a failing gasket or a leaking injector can also accelerate the need for engine repairs independent of miles driven.
Going by just the miles on the odometer would be foolish no matter what engine type you have.

Valve-guides usually need repaired well before 100,000 miles.
Valve-seals usually need replaced well before 100,000 miles.
Some LS1s have had problems with ring-seal, blow-by, and piston slap in as little as 20,000 miles.

The placement of the PCV port in the neck of the intake causes excessive oil to be pulled into the intake at high RPM, - the time when engine blow-by is increased. This causes more build-up on the valves, pistons, and combustion chambers, and is why the "Seafoam" treatment is so popular with LS1s. This can be avoided by running a fuel-filter or catch-can in between your PCV valve and the PCV port on the intake neck.

Atilla the Fun

valve seals come in under maintenance, not major overhaul. No point in redoing the entire engine when all it neeeds are new valve seals. That's an afternoon job in your driveway, at worst.

Convoy25

iTrader: (3)

hmm i see, stuff i would be able to do in my driveway i'm not that worried about, i'm thinking about the point to where its time to take the engine out and rebuild the whole thing.

but yeah i see the other factors as well. that being said, couldnt a 120,000 mile engine/car be in better shape than a 70,000 mile?

i guess when i was asking i was speaking as if our engines (gen II?) and the LSx engines were treated the same

305sbc

iTrader: (3)

Yes, an engine with leaking injectors or misfire that goes unchecked can be in worse shape in as little as 10,000 miles due to oil dilution and cylinder wash. Running E85 or other alcohol fuel can have the same effect.

Valve-guides cannot be repaired without pulling the cylinder heads. You can get an idea of the engine's general health by watching fluctuations on a vacuum gauge, compression tests, and leak-down tests.

The newer style of Viton positive valve-seals used on the LS1 last as long as the factory bronze guides.
The LS1 has a relatively high valve lift, a high rocker ratio of 1.7:1, and the rockers do not have a roller tip. If you look at the contact patch between the factory rocker tip and the valve tip, you can see that the geometry is not optimal for reducing guide wear. All of these factors contribute to accelerated guide wear, even with bronze guides, though the seals last longer than the older rubber & poly seals used in the SBC1.

Converting the LS1 valvetrain to use screw-in studs and guideplates with full roller rockers is expensive, but it does address some of the issues I mentioned, and is a great option for any type of performance build. It allows you to run much less preload with hydraulic lifters, and It's a better option than running spacers or compromising on rocker geometry.

The studs and guideplates can be had separately:
# 4856-8 guideplates,
http://speed-eng.com/store/comp-rock...s-p-10208.html

then you could just run your own choice of roller rocker arms to save money.
The key is to use the right rocker and pushrod-length combination to get the best contact patch on the valve tip. You want a narrow patch that is as close to the center of the valve as possible. Use an adjustable pushrod to set up the correct geometry. You must use hardened pushrods with the guideplates.

Some rockers will not allow correct geometry no matter what pushrod you use, due to their design. In this case it is best to try a different brand of rocker.

When it comes time to recondition the heads, or if you plan a performance build, then you should consider the valvetrain conversion for the sake of reliability and adjustability.