SBC experts--what mileage before major repairs?

[nel]

My '87 Corvette (L98 engine, aluminum heads, roller lifters, auto transmission) with 125K miles really needed valve stem seals badly. So, I took things apart and installed a set of roller rocker arms, new valve springs and retainers while I was at it. That got me thinking about when I'll have to tear into the engine again.

I don't drive aggressively nor a lot with this car lately (5K-7K/year). Other than an alternator, A/C compressor, intake manifold coolant leak, and a steering rack, the car's been reliable. The transmission does leak ATF from where the speedometer cable goes into it (I've added AutoRx to see if that'll help). And, of course, all the electrical connectors and other underhood plastic items have become brittle and break easily. Then there's the interior, which never was very good and has only gotten worse over time. And the weatherstripping, the non-functioning power antenna...the list goes on but they're more annoyances than anything mechanically fatal or major.

What are some of the major vulnerabilities of the SBC 350, and when should I expect them to show up? Transmission? Valve job? Your advice, please.

I've been itching to buy a new "fun" car but I know if I get started thinking about projects on this one that I'll be kept busy for awhile (and I'll probably end up learning something and spending less money in the process

).

 

[seotaji]

quote:

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with 125K miles really needed valve stem seals badly. So, I took things apart and installed a set of roller rocker arms, new valve springs and retainers while I was at it. That got me thinking about when I'll have to tear into the engine again.

I don't drive aggressively nor a lot with this car lately (5K-7K/year). Other than an alternator, A/C compressor, intake manifold coolant leak, and a steering rack, the car's been reliable. The transmission does leak ATF from where the speedometer cable goes into it (I've added AutoRx to see if that'll help). And, of course, all the electrical connectors and other underhood plastic items have become brittle and break easily. Then there's the interior, which never was very good and has only gotten worse over time. And the weatherstripping, the non-functioning power antenna...the list goes on but they're more annoyances than anything mechanically fatal or major.

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if you call that reliable, i'd hate to know what was unreliable.

 

[novadude]

On the older ones, I'd say the nylon-toothed camshaft timing gear, and the flat tappet cams had a habit of going bad in some years.

With yours, I would not worry. My Dad has a 1990 305 w/ 185k on it, and it is running great, and uses less than 1 qt between oil changes. Maintenance has always just been whatever dino was on sale, changed every 3-4k miles.

I had a 115k mile 1978 350 short block that I threw in my 1970 Nova. I added fresh heads, cam, intake and headers, and drove it hard, including 50 or so 1/4 mile passes (and much more hard driving on the street over 50k miles). The rings and bearings were untouched. It is still running great today at 165k on the bottom end.

At 125k, yours is just getting broke in! These engines go 200-300k easy, assuming you do minimal routine maintenance (oil changes, tune-ups, etc).

 

[TooManyWheels]

I have always used the 100-125K point as my cue to change the timing chain, but apparently other people are running way past that with no problems. The ones I've taken off have always proven to be stretched, however.

[ June 18, 2004, 10:52 AM: Message edited by: TooManyWheels ]

 

[nel]

I think expectations of reliability are somewhat personal. After all, my Corvette is over 17 years old . It's stranded me only once. As a former automotive engineer (emissions control, not engine hardware), I know what the trade-offs are when it comes to component selection. At the time I purchased this car, there were few alternatives that provided the same level of performance and driving thrill for the dollar. Parts are readily available and fairly inexpensive, too.

FWIW, my family has a '95 BMW station wagon. At 155K, it's required a rebuilt automatic transmission, control arm bushings, and a top-end rebuild because of a head gasket coolant leak, along with other components which I expect to wear out. That top end rebuild was really expensive (12 exhaust valves at $40 each, plus 12 intake valves, etc.)

I guess all this maintenance and repair work has got me thinking about my toy and what it'll take to keep it running.

Thanks for all the inputs. Please keep it coming.

 

[sbc350gearhead]

Go with a good double roller timing chain. Your engine should have a roller cam, so you shouldn't have to worry about it for a while. Most of the L98 problems, revolve around the TPI injection system itself.

 

[Bret Chase]

quote:

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Originally posted by TooManyWheels:
I have always used the 100-125K point as my cue to change the timing chain, but apparently other people are running way past that with no problems. The ones I've taken off have always proven to be stretched, however.

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my dad just had his timing set changed for the first time on his '90 GMC C2500... his truck's got 318,000 miles on it.

-Bret