Estimated cost to rebuld 1990 L98 to stock specs...

[HallenTi]

I am planning to rebuild the L98 in my 1990 coupe early in 2006. I will have it slightly overbored (.005 or so only) to true up the cylinders (has 158,000 miles and may have some obling cylinders). I will try to use any existing parts that are in good, servicable shape (crank, cam, lifters are new now, etc.) as I can. With overbore will get new pistons of course, possibly rods, will get new rings, all bearings, gaskets, etc. as well. Will remove the engine myself, but have machine shop bore after I strip the block. Will have the valves redone at that time as well.

I am looking to get some estimated costs (guess-timates) as to what this, with the basic machine shop costs, assuming most major parts are all reusable, might run me for parts and machine shop costs. I am in the Seattle area if that helps.

Thanks, Tim

 

[Moonunit 451]

Should be able to do it for a grand or less.

 

[SPANISHVETTS]

While you are in there why don’t you polish and port the intake and heads, throw in a set or roller rockers and balance/blueprint it. This will not run the cost up by more than a few hundred $ and it will give you the sweetest running ¨stock¨ L98 you can imagine.

I had an L98 built like this in Thunder before and it was so sweet that you could balance a coin on the intake and it would stand there while you revved the engine to redline and back. That motor cost less than $1500 to build and dynoed at about 290 rwhp. That is a lot of bang for the buck!

 

[HallenTi]

Sounds like a possibility as far as the blue-printing... smooth would be great! For certain reasons I think I have to keep the car a while (daily driver) so a rebuild so it is "just right" is the way I think I need to go. I'll look into the possibilities... thanks!

 

[MBDiagMan]

Just doing a thorough rebuild without getting caught up in lots of mods makes a lot of sense.

As far as what it needs, you NEVER, EVER know until you get it apart. An overhaul is always an exploratory surgery type operation.

If the engine has been cared for and not abused with frequent oil changes, you could very possibly get by with a good valve job, reringing existing pistons leaving the bores alone and engine bearings.

With the roller cam, you will most likely not need to replace the cam and can often even reuse the roller lifters.

If you do a rering I will tell you what I have done with great success to a number of engines. It is against conventional wisdom but has been proven effective by Ryder labs. If the cylinders mic out okay and pistons are in good shape with no excessive ring land wear, I use cast iron rings and DO NOT hone the cylinders.

You can get ready for a fire storm here because everyone has been honing cylinders for reringing for 100 years, but with cast iron rings it is NOT necessary. Honing the cylinders only takes away more cylinder. I have seen with my own eyes an engine that was taken apart after 500 miles that had been done this way and the rings were seated. It is a totally workable situation AS LONG AS cylinders mic out to spec.

There are several makers of cast iron rings including Continental and I think Speed Pro makes a cast iron ring that is called the Quick Seater.

Also on ANY small block Chevy, ALWAYS, ALWAYS, ALWAYS see to the valve guides during a valve job. The SBC is weak in this area. The best approach IMHO is to use what are called "Bronze Wall" guides. DON'T let any shop do what they call a knurl on these guides, it will last no time. The Bronze Wall consists of tapping the hole and inserting a bronze helicoil that then gets a tool driven through it to seat against the threads, then reamed to size. It will last longer than the original guide surfaces.

Plan on replacing the oil pump and timing chain set for good measure.

I enjoy building or rebuilding engines and have done a number of them. If you have any questions, chime in.

BTW, if you are doing the work yourself and not buying any speed parts, I expect $1000 will cover it. Unlike most Vette owners I am not of the belief that the small block Chevy is the best engine ever built, it is far from it, but where it shines is at rebuild time just because they are so common that parts are cheap and they are a very straight forward engine to rebuild.

Good luck,

 

[Edmond]

Sweet, this is kinda what I'm also planning too. However, I got a set of ZZ4 heads in the garage and some new injectors (stock 22 lbs.) that I'm going to use.

I also plan on going with 1.5 roller rockers and a little bit more cam but not much.

 

[HallenTi]

MBDiagMan, I do plan to do the basic work (except the machine work) myself, and appreciate the ideas you have there. While I had thought about having the valves done, I hadn't given any thought to the guides, so that is an excellent point. Once I start in on all this, I will sure keep that in mind. I'll also take a look at the possibilitiy of the rings without a bore/hone. Of course, I will have to make sure the bores are ALL OK before I get that far. I am reading what seems to be a very good, practical book on the subject, which goes from planning what to do, disassembly, inspection, maching shop tips and what to ask and tell, and reassembly. So, once I finish the book and take in all that has been and may be said here, I will have a good feel for what is in store.

 

[wildbill486]

I rebuilt a 283 once (with cast rings) for $89.95

Thing turned 8000 rpm plus with a solid lift cam.

 

[MBDiagMan]

Yep, those were the days. They were good and bad. The good was that parts were cheap and cars were much easier to work on. You could get a kit for $89.95 with rings, bearings and gaskets, do an inframe overhaul and back on the road.

The bad was that engines needed all that care quite often. Now with fuel injection instead of a carburetor, there is no raw fuel at start up, washing the oil off the cylinder walls and wearing out bores, rings and pistons quickly.

Tim,

For the reasons stated in my last paragraph, it is very possible, if not likely that you will find your cylinders mic out to spec and will not have to rebore.

BTW, unless the engine has been driven RIDICULOUSLY hard, you will not have to do anything with the rods even if you must rebore and go to oversized pistons.

Keep us informed on your project,

 

[Larry's Yellow Rdstr]

I had the same idea to rebuild my 104,000 87 to basically stock specs. I called a local mechanic with excellent references and discussed this with him. Somewhere in the conversation we went downhill pretty quick. He says with a "little" more money we can get 350 HP out of my L98. I'm thinking around 2500 or less. He says $7000.00. I can buy a high output short block, add a great cam and do the heads with a 3 angle for a lot less money.. Somewhere we had a failure to communicate.

Is there a sign painted on my forehead that says, "tell me anything I'm really stupid"

 

[SPANISHVETTS]

I had the same idea to rebuild my 104,000 87 to basically stock specs. I called a local mechanic with excellent references and discussed this with him. Somewhere in the conversation we went downhill pretty quick. He says with a "little" more money we can get 350 HP out of my L98. I'm thinking around 2500 or less. He says $7000.00. I can buy a high output short block, add a great cam and do the heads with a 3 angle for a lot less money.. Somewhere we had a failure to communicate.

Is there a sign painted on my forehead that says, "tell me anything I'm really stupid"

For 7 grand that motor had better be stroking & smoking with around 500 HP. I do not have much over ½ of that amount in Thunder’s 383 and it was done right with no corners cut and all GM performance parts.

If the lower end is ok, and I will bet that it is, the head work will be the majority of the cost.

Got to go now, more later.

 

[Edmond]

If the lower end is ok, and I will bet that it is, the head work will be the majority of the cost.

Got to go now, more later.

Isn't it sometimes cheaper to just buy an aftermarket set of heads such as AFR or Edelbrocks?

 

[MBDiagMan]

Aftermarket heads are in the area of $1000. A valve job and bronze wall guides will cost somewhere in the neighborhood of $150 to $200 depending on your machine shop.

Have a great day,

 

[HallenTi]

Doc,

Thanks for the estimate on the valve job, including the bronze guides. My heads are fine I believe (have had one off recently for another repair and it checked out just fine, so assume the other is the same - of course, you can never tell) so aftermarket heads aren't in the cards for me. I have read differing opinions on steel vs. bronze guides, but it sounds like you recommend the bronze units, correct?

 

[MBDiagMan]

I strongly recommend the bronze wall guides. They are a bronze helicoil that is reamed to size. The shape of them seems to hold enough oil to make them last forever. I have seen engines come apart after running bronze wall guides for 150,000 miles that did not need the guides redone at that time. I have never seen SBC original steel guides that did not need attention after that amount of time. As far as I'm concerned bronze wall guides are superior to ANYTHING that can be put in there.

Good luck,

 

[G Winter]

With heat bronze tends to absorb some oil making it in effect self lubricating.
In my opinion this should make them last for a very long time.The only thing I see tha could begin to be a problem is the differents in expansion rates. I would go with the bronze.
Glenn