swift700

iTrader: (3)

Hi guys, I need a definitive answer on this. I don't need any recommendations about buying or using other, more suitable blocks. I just need to know if an aluminum-blocked 5.3 can be bored out to 3.905" for use as a 5.7 sized stroker. There seems to be a lot of conflicting opinion on this. Thanks for any experienced or well-researched advice.

The_Rizzle

iTrader: (4)

Not unless you sleeve it, but then you might as well go bigger.
Same reason an ls1 can't go to 4.00" bores. The sleeve is only so thick, and not made to much bigger.

swift700

iTrader: (3)

I've read that the sleeves in these blocks are thick, with the outside diameter being the same as with the 5.7 sleeves. This would allow the same maximum bore as the 5.3

Did the sleeve thickness vary between the LM4 and the L33 5.3 blocks? This could account for for variances in opinion.

5.3LJimmy

iTrader: (10)

I think the LM4 and L33 use the same block and liners. The issue is with the LH6 which is a Gen 4 aluminum 5.3. I too have seen lots of conflicting info on boring the aluminum 5.3 blocks and would be hesitant to do so without sonic testing. All the Gen 3 Aluminum 5.3 blocks I have seen have had a noticeably thicker sleeve than a 5.7, but I have never seen a newer 5.3 with the heads off.

The_Rizzle

iTrader: (4)

I have an l33 block sitting in my basement, and went to check out what you guys are saying. I'll have to check what an ls1 block sleeve looks like in a bit, since I have one of those in my shop. However, if the block is machined out for the sleeve, then the sleeve is pressed in, there isn't enough material to make it ls1 bores, since the sleeve doesn't go past bottom of the bored hole. This makes the sleeve thickness quite visible. It looks like the sleeve is less than an 1/8 thick, but I'll do some measuring. Pictures too, if the camera wants to co-operate today. Might as well take pictures of both to compare.

swift700

iTrader: (3)

The reason I need to know this is that I can buy a new Gen III aluminum block 5.3 that's been bored out to 3.900" already. I want to hone it a further .005 for a 383 stroker build. The remaining sleeve looks fairly thick but I'd sure like to hear from anyone who has built a similar engine from one of these blocks. Has anyone done this or know of anyone who has? I'd sure like to hear from them beacause I can get this block for $450.

The_Rizzle

iTrader: (4)

Ok, looked at both, sleeve at bottom looks very similar in installation and thickness from the l33 block to the ls1 block. The coolant "holes" on the l33 are done nicer, are bigger in shape, and flare out more at the top, so that my verniers notch couldn't read the thickness of the block and sleeve properly. It was just over 10mm w/ the vernier touching the wrong spot (notched out section), still had at least another mm to go. Thickness of the LS1 block was 8.5mm, vernier working properly.

So with the l33 block/sleeve thickness working out to roughly 9mm, the ls1 block at 8.5mm, i think the same rules apply to the l33 and the ls1 bores.

I personally wouldn't even consider oversizing the l33 any more that ls1 guys go over, which is .010?

swift700

iTrader: (3)

Do you mean .010 oversizing from the stock 5.3 bore or all the way up to the 5.7 bore, then .010 over that?

What is the outside diameter of both sleeves? Can you measure that?

Thanks for the great help!

The_Rizzle

iTrader: (4)

I am saying that I wouldn't go much more than .010 from nominal bore size of a 5.3 with the l33 block unless approved of by the machinist. That would be 3.78" + .010". If you took the block out to ls1 specs i don't think there'd be much material left of the sleeve.

As for measuring the outside dia of the sleeve at the bottom of the bore, I don't have the proper tools. There isn't enough room for a dial bore gauge to do it, and I don't have telescoping gauges. If I did manage to find a way to do it, it wouldn't be very accurate.
Both sleeves look very similar in thickness, not diameter, which is why I would think oversize amounts would also be similar.

swift700

iTrader: (3)

OK, thanks for checking. I talked to the guys at Texas Speed and they said they knew of a few guys who have made 383's with the aluminum 5.3 block. My local shop said they used to sell quite a few of them before the 403 became popular. There seems to be enough evidence out there that these blocks will work at the 3.905 bore but I'd sure like to talk to someone who has built one. Definitely more research is required.

Bilster

iTrader: (21)

I can have the most definitive answer of all if you can wait until the end of the week. I've been wondering the same thing and most experts say yes. I have an LS6 block with a standard bore and a 5.3 aluminum block. Both blocks are constructed identical as far as I can tell but I haven't brought it into the shop yet for precise measurement. I'll take pictures of both sleeves, compare the thicknesses of both sleeves and might even do a cylinder wall thickness check.

Just a block for $450 seems steep. I got my entire short block for less than that. I got my standard LS6 bare block for $200. IMHO, I would look for a standard 5.3 block. That way you could put plate hone the thing and have a really nice bore.

The_Rizzle

iTrader: (4)

Did they say it was with the factory sleeves, or re-sleeved blocks? Big difference. I'm sure you could make it a 427 if you wanted, just costs a little $$ to get the aftermarket sleeves put in.

Do you have the block you can look at? If so, which one do you have.

You can still stroke the 5.3 block, but that doesn't end up at 383.

I personally wouldn't do it, I have both blocks to look at and theres no way an l33 block would be reliable to run at a 3.905 bore with any peace of mind. It's not like the iron blocks where theres more cast iron behind it. It would be a thin sleeve with aluminum casting behind it.

Looking at the top doesn't do it justice.Theres a lip o hold the sleeve in place. Look at the bottom where you can see the thickness of the sleeve. I figure the sleeve is less than an 1/8th inch thick, and you'd be boring it over that much (exactly .125), so there'd be less than 1/2 of the sleeve walls left.

Hey, its your block (or will be, if you don't have it yet) so its your call if you really want to try it.

swift700

iTrader: (3)

I think it was with factory sleeves. At any rate, I might look at buying a 5.7 block instead and have some peace of mind. Anyone know which one has the sensor locations that are the same as the Gen III 5.3?

I have the pistons already so need a block with a 3.905 bore. I prefer an aluminum block to offset the weight of my blower.

The_Rizzle

iTrader: (4)

Now you say you want to put a blower on it?

All ls1 and ls6 blocks will have the sensor locations in the right spot. The ls2 started the gen IV stuff.

Either one will work fine.

swift700

iTrader: (3)

Yes, I have a new Magnacharger 1900 blower to go on this engine. I also have ported 243 heads with 2.02 valves, and -18cc dish pistons that should make around 9.4:1 compression. I just need a block...

Can I still buy a new LS6 block from GM or are they discontinued?

5.3LJimmy

iTrader: (10)

The stock LS1/6 sleeves are right at 0.060" thick, so if the .125" was machined out he would have the same thickness as a stock LS1. I think from your measurements that it would be okay to bore.

swift700: It would be a good idea to have the block thoroughly checked prior to machining instead of asking people on the internet that can only guess what the answer is. Most people only repeat what they have been told and have no personal experience on the matter. I have seen people that have bored the 5.3 aluminum block to 3.905 and run it, and I've seen people that have never done it swear that it can't be done.

I agree that the $450 for a bare block is quite high if it is used. I have seen complete running engines with accessories go for $500. Where are you located? I know someone that has 3 LS6 and 1 LS1 block in his shed.

The_Rizzle

iTrader: (4)

The machining at the bottom of both engine sleeves look very similar, with the bottom of both having a taper. However, with the light in a different spot when I just went to try and prove that you can't do this, found that the sleeves in the ls1 block are definitely thinner in what is exposed. The block itself adds to most of the taper in the ls1 block, while the sleeves in the 5.3 block make up all the taper.

I did my best at getting a good measurement of the 5.3 block first, theres about 1mm of sleeve thickness at the bottom exposed. On the ls1, its not even close, maybe .3mm. My early statement of less than 1/8 was based on sight, and that seems to have been a little big.

To go from an 5.3 to an ls1 bore would take 3mm, so at 1.5mm per side, you'd probably be boring block at the bottom when the taper was before.

I still don't think they're the same dia sleeves that would let the 5.3 go out to the ls1 bore size. I also don't have any tools to measure sleeve thickness in the middle, with a sonic tester, so my opinion is based without concrete proof. It is not made without any experience in the matter, however.

I've gotten as many decent measurements as I can, its up to you to decide for your engine.

swift700

iTrader: (3)

That $450 is for a brand new block, cam bearings installed and bored out to 3.900 already. I just want to hone it to 3.905 for my pistons. I'll have to go back and check the bottom of the sleeves and then have the block sonically checked. What is the minimum thickness required?

I don't really care about how much it costs, I just want it to work. I'd buy an LS1 or LS6 block to ease my mind about the whole matter if I could find one locally but they seem rare around here where I am in Canada.

Thanks again for the input, guys.

1SLwLS1

iTrader: (6)

You are talking about a 1 cubic inch difference between the 3.900" bore and the 3.905" bore with a 4" stroke.

3.9000 / 2 = 1.9500 * 1.9500 * PI(3.1416) * 4.0000(stroke) * 8 cylinders = 382.2699 ci

3.9050 / 2 = 1.9525 * 1.9525 * PI(3.1416) * 4.0000(stroke) * 8 cylinders = 383.2507 ci

383.2507 - 382.2699 = 0.9808, less than 1 cubic inch difference. Why all the sweat over 5 thousandths hone?

Nvm, I see you already have 3.905" pistons. Why don't you just buy a used LS1 block? You can find those for pretty cheap.

The_Rizzle

iTrader: (4)

Where in Canada are you?