I bought an '89 6 speed with Z51/FX3/J55 with 85K on the ticker last September to serve as my track car, as I use my A4 '94 for DD duties, cruises, shows, etc.

This car has been a 'problem child' from the start, with just working out gremlins, but whatever, I can deal with that. I have no issues with it being a project as I intended to go through it slowly and upgrade, but I have now run into a serious problem that I need advice on.

A friend ran a leak down test for me with some not so good results. Cylinder 1 and 3 came back at 12% which is fine, but cylinder 5 came back with a whopping 30%. He said he could hear the air blow by. At that point, he stopped the test. Additionally, there is blue smoke, which probably means that it is burning oil and the valve seals would need replacing. There could be even more issues that we haven't found yet, who knows...

Now I need to decide what to do. Obviously the bottom end has issues. Any thoughts on what to do? Are there any repairs that can be done? Rebuild what I have? Replace just the bottom end? Get a new engine altogether? Recommendations on parts or engine components or companies to deal with? As I said, I had intended to beef up this thing at some point...although I didn't think I'd be doing it this soon. I guess it never comes at a time that is convenient.

Everybody, please weigh in with your thoughts...thanks.

 

How can you go from a leaky valve seal to a bad bottom end?

That is a killer leap!

I have to ask, tho... what is your definition of the "bottom end?" The standard is everything in the block, including the block.

An L98 with that mileage will have **** for valve seals. Don't be surprised.

Since it's a track car, I would rebuild that block, converting it to 4 bolt main with splayed caps and take your time building it. All the right forged components, balance, blueprint. Just do it right.

Get the transmission checked out and select new rear gears to go with new motor.

 

How much do you want to spend, how fast do you want to go, what do you really want to use the car for? Who is doing the work?

 

The simplest solution, and it's recommended once again in this month's Corvette Fever, is to buy a ZZ4 crate motor and use your TPI manifold, distributer, and water pump.

Really, an engine that's just plain worn out at 85K miles has been either neglected or abused. My LT1 was fresh as new at 80K miles when I had it modded, while that L98 is junk right now. Who knows what you would find wrong once you delve into the block. Since you don't know the real history of this car I think the best way to start fresh is with a crate motor. You will be spending a lot on the brakes and other stuff anyway.

 

Like Bogus said going from valve seals to bottom end is a serious leap. Why not put valve seals in it and drive it to get the other bugs out. While doing that buy and build your track engine. That would at least spread out the expense to your pace. like they say "speed costs money, how fast do you want to go?"

 

She's been trying for months to fix it and drive it to get the bugs out. It's hopeless and she needs the track engine now. The question is how much power does she need, as compared to how much reliability does she need to get her track time.

This car has been a total mess since she bought it, and the repair work up until now has been done by the best Corvete mechanic in the area. It's time for a new approach.

No one knows how abused the car was before she bought it, except it appears to have been trashed, so we can't assume that anything under the bonnet is really good.

 

Some smoke on start up or decel is seals,(worst case scenario guides) no big deal. L98s are notorious for having head gasket seepage bet. #5/#7....Even pressurizing the cooling system is hard to diagnose it with (until the leak gets bad), been around that block recently.

If it were me, Id tear the heads aff an inspect for leakage, check the heads for cracks-If all checks out Ok give the heads a quick surface and reassemble it so you can finally get some drive time in the car while you build something more stout.

I suppose rings in one cylinder could go, but highly unlikely with only 80k miles.
Take it one step at a time.

 

FELNGR8 is right on as he knows the history of the car since I bought it. Obviously the car prior to my purchase was abused/neglected, it's just that the previous owner was not very forthcoming about it (not happy about the misinformation, but I bought it with the expectation of it being a project car anyway). So when someone tells me at the very least it needs a new bottom end, after all that I've been through since September, then I'm inclined to believe him/them. It may seem like a huge leap to you all, but as Chuck said, you've missed quite a bit of the history.

That being said, I am just trying to feel out options from the C4 T/P group. What set-ups you are running, what the costs were, who you used for parts, etc.

This car will be used primarily for circuit work but must remain street legal/emissions friendly as I do not have a tow vehicle. Would like as aggressive a set up as possible without having to tow it to a track. Also, something that I can build upon and make faster just in case the money well runs dry. 250BHP was never going to satisfy me for long, but if I am forced to do engine work anyway I might as well beef it up some.

Any thoughts?

 

Leak down test results:

http://forums.corvetteforum.com/show....php?t=1392009

 

So another L98 won't be thrill enough?

Are you ready for this? http://www.sdpc2000.com/catalog/120/...inum-Heads.htm

It weighs the same as the L98, and the work to put it in would be about the same. It's only money.

 

Here are the results.

1 - 11%
3 - 12%
5 - 30%
7 - unknown
2 - 32%
4 - 10%
6 - unknown
8 - unknown

 

HOw? Well she wanted a heads / cam package / mini-ram, etc... I and other people suggested she have a compression or leak down test done to get the overall health of the engine. To me it didn't make sense to bolt thousands of dollars worth of parts to an engine with issues.

 

Hardly seems like a "killer leap" to me. Faulty valve seals ain't gonna cause ugly leakdown test results.

That engine is ready for either a rebuild or to be put out to pasture.

The ZZ4 option is one that I'd look pretty hard at, as others have noted.

Be well,

SJW

 

Can anybody give any specifics on their set ups? Engine and associated parts, costs, HP/TQ #s? Like I said, I have an '89 that I will be working with.

TIA

 

Are you looking to build it yorself, or???


You could always go the route Bluewasp did, and get a crate longblock from SkogginDickey

 

As I stated above, I am looking for specific information, so that I may weigh the options and decide what is best for me.

Anyone who can answer, please post

 

i suppose what i can suggest for you depends on what you consider track duty. auto-x, drag racing, road racing, etc?

would you prefer gobs of torque or a high winding motor? what gears do you plan on running?

 

On a cylinder leak down test. You apply the the air via the spark plug hole, with piston on top dead center (both valves shut). Then when you get a bad cylinder, you listen at the exaust to listen for air leaking (burnt exhaust valve, or stuck). you listen at the throttlebody if you hear air leaking (burnt intake valve, or stuck). you listen at the oil fill hole, if you hear leaking (piston rings, excessive wear on cylinder walls) You look at the radiator if bubbles ( bad head gasket, or warped head). That's the way I learned it, and I hope it help you diagnose your problem...

 

Circuit track duty. Think Summit Point, Watkins Glen, VIR...

Car has 3.33 gears but can be changed eventually if need be. Really looking to see what set-ups people have, who/what they used, costs, dyno numbers, etc. Trying to research fully before pulling the trigger.

 

so it's pretty much gonna live it's life in the upper part of the RPM range...low end not a terrible concern...

it'll take me some time, but i'll see what i can dream up with part numbers and a cost sheet...i'll toss it into Desktop Dyno and see what it pulls...it's usually fairly close within 5% or so to real world numbers as long as i input the flow numbers for the heads...

i know with as much track time as you'll put to it, whatever you do...use a good forged and fully balanced rotating assembly