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Boring 60 over, possible with sleeves on the L03?

Old 04-09-2019, 03:30 PM
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Boring 60 over, possible with sleeves on the L03?

We are doing an L03 bore and stroke. Before you 350 nuts get your flame fingers all fired up, this is my highschool car that ive had for 17 years, more than half my life. Any other L03 engine, I wouldn't even bother to rebuild, but this one is special.

We were originally going to do a 334 stroker (30 over on 3.75 crank). After dismantling, the bores are pretty bad, theres a lot of piston ring wear at the top of the bore and 30 over may not be enough. I was ready to kick the damn thing and let it rest in pieces. But someone suggested a 60 over bore could do it. From what ive read, 30 over is considered the max safe bore because of water jacket proximity in these small bore engines.

Has anyone done a 60 over on the L03 / LB9 blocks? Would it be safe under 8.5:1 dynamic? (aluminum TFS 175 heads are on it so it should cool well enough to handle that kind of dynamic) I'm not familiar with sleeving, ive never had to use them. When you bore a little more than 60, then put a sleeve in there to offset it back to 3.796 (a little more obviously because of expansion and the forged pistons im using), is it going to help strength at all when it comes to avoiding breaching a water jacket? Is it even nessisary to sleeve it at 60 over? I mean how 'unsafe' is an L03 over 60 at high compression?

I need to speak with a builder or machinist who is fimiliar within the L03/LB9 blocks on this one.
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Old 04-09-2019, 03:41 PM
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Re: Boring 60 over, possible with sleeves on the L03?

The universe is trying to tell you that you're playing with fire, and need to cut loose the boat anchor. FWIW.

It's just a lump of iron. Hold a small ceremony, say some sweet words, and send the old block to the Golden Goat.

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Old 04-09-2019, 04:59 PM
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Re: Boring 60 over, possible with sleeves on the L03?

Not giving up on it. But either way, even if i dont have a choice for whatever reason, its still getting another 305 boat anchor put in it, so would be nice to know if i can pull off the 340ci thing with them. They make pistons for it, so someone has obviously done it, but they seem to be unicorns. People tend to write these blocks off thinking the 170hp rating is an omen to what it does when theyre built. They don't realize you can get 360hp out of them with just a good set of heads and decent cam. When you start to bore and stroke them, they come alive. Funny that so many people call them boat anchors, and respect the 327 engines. But the 30 over bore and 3.75 stroke 305 blocks turn into a 334. Lots of misinformation and misunderstanding on the internet. Thats why I need to speak to a seasoned gen 1 SBC builder or machinist.
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Old 04-09-2019, 05:12 PM
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Re: Boring 60 over, possible with sleeves on the L03?

They're considered "boat anchors", because while it IS possible to get 360 HP from a 305, you're going to spend far more time/effort/money that you wouldn't have to spend building a 350 to that level, or beyond.

Is there a reason you are determined to continue with a 305?
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Old 04-09-2019, 05:17 PM
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Re: Boring 60 over, possible with sleeves on the L03?

Originally Posted by Galaxie500XL View Post
They're considered "boat anchors", because while it IS possible to get 360 HP from a 305, you're going to spend far more time/effort/money that you wouldn't have to spend building a 350 to that level, or beyond.

Is there a reason you are determined to continue with a 305?
Quoted for truth.


I don't think people are trying to dissuade you from doing it "cause 305's suck", they are doing it because it's false economy to even begin to build a serious 305. If you have a pile of money sitting around and want to do it "just because", then have at it.
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Old 04-09-2019, 06:05 PM
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Re: Boring 60 over, possible with sleeves on the L03?

Originally Posted by devwolf View Post
They don't realize you can get 360hp out of them with just a good set of heads and decent cam. When you start to bore and stroke them, they come alive.
Aw hell yeah dawg. I mean just look around, the 305 SBC was pretty much THE V8 in thirdgens. Only 176,000+ registered members here, and look at all the *** kick'n 305 stroker builds. I'm sure you dont see them just because no one ever thought to try it, or they got sick of hearing it's impossible. I mean I'm sure there are THOUSANDS of folks out there, with 305s bored and stroked with a good cam and heads and the 360hp dyno sheets and 13 second 1/4 mile time slips, they don't post them and set everybody straight, because they're keeping it sleeper so the Neon SRT boys don't know what he's got hidin under the hood. Don't want to give away the secret.

Look, I'm not trying to rain on your parade, but I've seen thousands of people make claims like this and say they're gonna build a 360hp 305. I've seen maybe a half dozen threads where someone posts the results of their 305 build. Of those, most agree they would have been better off using a 350 block.
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Old 04-09-2019, 08:51 PM
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Re: Boring 60 over, possible with sleeves on the L03?

I tried hopping up an LG4 and it was no faster than a stock LB9 when I got done with headers, cam, and carb swap. Trust me it's not worth it. Sell it for scrap, you can't put enough lipstick on a pig.
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Old 04-11-2019, 05:22 PM
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Re: Boring 60 over, possible with sleeves on the L03?

I think you guys totally missed the point here, read the car's background. And for the love of cars, quit repeating things people tell you. Lmao. Car culture is not about who makes more hp, get over it . Also, as for that 360hp build, that cost about 1500$ total. Which is way cheaper then buying an L98 and rebuilding it, and still get less hp. You still gotta buy more **** on top of that to get over that 360 mark the 350, and if you already have an LO3, well... you do the math. But again thats *not the point*
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Old 04-11-2019, 05:35 PM
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Re: Boring 60 over, possible with sleeves on the L03?

To answer the original question, you would have to have the block sonic checked over at a machine shop to see if it can handle the over bore and sleeves. Nobody over the internet, phone, mail, smoke signals ect can tell you for sure. Chances are it won't but who knows.

FWIW the 327 was a 4" bore motor so it's not even a comparison, and the 360hp 305 motor for 1500$? I'll believe that when see it.
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Old 04-11-2019, 06:49 PM
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Re: Boring 60 over, possible with sleeves on the L03?

You can pick up a NEW 350 Vortec crate engine direct from GM for about $2k. There's no world where rebuilding a 305 is even remotely responsible of fiscally reasonable. You'll spend more turning that garbage into garbage that smells like you threw perfume over it, than if you just manned up and accepted that no one is trying to keep you from your delusions of 360hp 305 grandeur, we're trying to help you realize that your expectations are unrealistic and foolish.

But hey, you just keep marching to your crazy drum. When it doesn't work out the way you expect, you can come back here and tell the next guy he's dreaming, and tolerate his flippant responses telling you that you're just a hater.
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Old 04-12-2019, 03:17 PM
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Re: Boring 60 over, possible with sleeves on the L03?

Why does the vehicle's history have anything to do with the viability of some old 305 that was it in?

Get a used Vortec and rebuild that. If you really want to make it look like the part, deck the block and then punch the serial numbers and $hit from the 305 into the newly surfaced deck so it is "numbers matching". LOL.

Huge waste of time and effort. Trust me the car has no feelings toward you - if it did it would probably ask you for a 350.

Why don't you treat your beloved car with some respect and give it the performance it deserves?

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Old 04-14-2019, 12:53 AM
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Re: Boring 60 over, possible with sleeves on the L03?

You don't have to be rude and talk down to him, guys. You know, treat others how you want to be treated?

The fact of the matter though is that a 4" bore lends itself better to a performance build with 2 valve heads than a 3.736" bore. You will also be able to buy better, forged pistons then being stuck with some Keith Black hyperpathetics. I had a hypereutic piston fail on me and take out my block and snap my crank, so the label is warranted and I will never use them in anything performance oriented again. Piston speed is a lot faster in a stroker, so good quality pistons are even more important. People don't trash on the 302 sbc, and the sbf 5.0 was a huge success - both with 4" bores. My vote is to get a 350 block, then stroke it to 383. Or skip stroking it, because a 350 is still bigger than a stroked 305. To find a 350 block and have it bored .030" is going to cost a heck of a lot less than sleeving the 305. If we were talking about Fords here, I totally understand why people stroke 5.0s instead of going with 5.8s, but externally a 305 and 350 block are the same.
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Old 04-14-2019, 04:48 AM
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Re: Boring 60 over, possible with sleeves on the L03?

Originally Posted by 88RS View Post
You don't have to be rude and talk down to him, guys. You know, treat others how you want to be treated?
If I went around talking about 360hp 305 builds, I'd hope to hell someone would be caring enough to tell me straight, that it's a pipe dream, BEFORE I blew my money chasing that dream. Better to get a rude awakening, reality check paid in full, than to be the sucker that falls for Black Echo's Special Performance Online TBI malarkey.
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Old 04-15-2019, 08:02 AM
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Re: Boring 60 over, possible with sleeves on the L03?

Just have a shop sonic check it to see how thick the walls are. Noone can tell you if it can be done or not and their experience wont be relevant because cyl wall thickness may vary from block to block
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Old 04-15-2019, 09:53 AM
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Re: Boring 60 over, possible with sleeves on the L03?

Originally Posted by devwolf View Post
I think you guys totally missed the point here, read the car's background. And for the love of cars, quit repeating things people tell you. Lmao. Car culture is not about who makes more hp, get over it . Also, as for that 360hp build, that cost about 1500$ total. Which is way cheaper then buying an L98 and rebuilding it, and still get less hp. You still gotta buy more **** on top of that to get over that 360 mark the 350, and if you already have an LO3, well... you do the math. But again thats *not the point*
So I take it that you want to save this engine because it was your original in your car from high school etc....I get that. I would look into getting another 305 block with decent bores and go from there before I'd bore one to .060 over. Heck, you might find a good running one you don't need to rebuild at all. Guys seem to yank out good running 305's all the time from these cars.
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Old 04-19-2019, 11:12 AM
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Re: Boring 60 over, possible with sleeves on the L03?

when my LG4 started knocking I decided to make it better accelerating and went 350- look forward the only difference from 305-350 is bore I was happy with the rest of the car was doing Oh and when I tore it down I found the 305 block was cracked in lifter valley boo hoo and I finally knew why it had a slow coolant loss is the LO3 a roller block? if it isn't there's another reason to upgrade it if the 305 was everything to you build a shrine in the garage for it
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