All eyes,

Is it me or the camera, but looks like the pistons are undersized. They look like std pistons in a 0.060 overbore.
I can see quite a bit of the piston rings. Which indicates way too much piston to wall clearance.

I agree, something fell down in the bore and struck the pistons a few times before exiting.
But those pistons are far from anything considered performance, dish tops and huge valve reliefs.

 

@HeadsU.P. I hadn't considered that! This is my first real engine teardown and everything else on the motor looks pretty stock, down to some of the emissions gear. I assumed the pistons were untouched as well but maybe not. I'll definitely be pulling them out when I'm up there later this month.

And yeah, I for sure want to upgrade them with something better if any money is going into this block.

 

Before you spend a dime on that block (I'll give you my L48 block for free), consider a later Gen 1 SBC instead. One with a stock roller cam, like an L31, ZZ4, or (late) L98 engine.

There's zero reason to put any money into any L48, let alone one that isn't stamped with your car's VIN.

 

I disagree.
To the left <<<< is mine. What's left of a L48.
Bored over, dome pistons, new heads, blah-blah-blah.

Close to 430 horse now. (Simulated dyno info)

You only need 4 bolt mains if you tend to scream the crank all the time.
Otherwise 2 bolt just fine for street occasional 1/8 mile drags.

 

Stock roller cam. Nothing to do with 2 vs 4 bolt mains. I've seen running L31s for $500- on Facebook. How much does a roller cam conversion cost for that beat L48, not counting everything else it needs?

 

Some good and valid points above. Yes a L48 block can easily be a 400 HP engine. And parts are readily available and affordable to do so.
Yes a roller block is even better. Absolutely no doubt.
I run my original gen 1 flat tappet block. Numbers matching and running about 400HP. Which is plenty fun in these old cars. Yes my numbers match. But the guys that care about that stuff want to see date stamps on alternator cases that match and the correct markings on bolt heads and such. So just having a matching vin on the block means little without Absolutely every little detail factory original.
So, sometimes it's the devil you know that's worth running with. You already have a gen 1 block. If it's in great condition, why not hone it and put in some hyper pistons and a set of decent heads.
Yes you can spend more money on a roller block. And potentially make even more power. And then you can break more stuff behind the motor.
It never ends.

 

Yeah, my idea was to start with a stock motor and do some beginner-friendly upgrades to it over time. I've heard about the roller cam blocks but since I already have one I figured it was a good candidate to learn on, plus, my dad's '77 is completely stock from the intake down, so any upgrades I made to mine would be a great 1:1 comparison.

If I ever come across a later block like that, I'd happily ****** it up though. I had a lot of fun tearing the current one down, so I know it won't be my last.

 

Cool, keep having fun!

 

Perhaps I misunderstood. Previously, you had said this:

Which made me think that the beat L48 is not original to your car, and owes you nothing.

By all means, take it apart, learn all about SBCs, etc. That is awesome stuff. But beyond the learning opportunity, a free, non-matching L48 that needs pistons, a cam, and possibly crank and cylinder work, is worth less than zero. If you want a platform to build off of, you will be miles ahead starting with a running engine. You will spend more on a set of pistons than the cost of a running roller-cam engine on Facebook. That was the point of my post.

Here's an example. A complete L31 for $500- (Facebook link in Richmond, VA, which may or may not post on the Forum). I'm sure there are some near you, too.
https://www.facebook.com/marketplace/item/644992748503621
And my offer stands. If you can use it, I'll happily give you the L48 out of my own C3. I've already done the math. It is worth no more than the scrap weight of steel. I'll give it to you for free.

 

A set of hyper flat tops/ rings

 

@Bikespace I know the roller engines are a definite upgrade over the first gen blocks, but is the difference really that big in the long run? I figured the later LS-style blocks with fuel injection and computer control were the bigger upgrade. I'll definitely keep an eye out for one of those later blocks in my area but I figured I'd be changing the cam either way. Would you keep the stock 90's roller cam in there?

My plan originally was to probably throw in some fresh rings and gaskets for now and play with it later, but at this point I'm revising that to flat tops, a 260H or 268H cam, and eventually some 64cc aluminum heads.
I realize that's more money in parts than the motor is worth but I already considered it to be a bit of a burning cash pile and I didn't have many other options anyway. Plus, like I said, more about the journey and learning and less time googling how to adapt something else into the car.

And you are correct, the L48 I'm working on is a Marketplace donor, not matched to the car, other than the fact that it's from a donor of the same year.

@4-vettes thanks for posting those! I was actually just doing some research on which pistons would be appropriate to buy as replacements, although I'm obviously going to wait and check the measurements first to find out if anything is over or undersize.

 

No worries, I just wanted to make a point. A set of 8 pistons and rings of decent quality can be had pretty cheap. You really can build a decent 400 HP engine out of the old L48 fairly inexpensively. And ALL your accessories will fit! And your radiator will fit, and your exhaust will fit, etc. etc.

 

If you learn something along the way, and end up with a running engine, that could make it all worth it.

Good luck, and enjoy the journey!