talking locally at a FB group floated on a doubt

if we have a 318... can be overbored 0.090" to a 360 std diameter ( 4" ) ? if not... why ?

my first guess is due the cilinder wall thickness... but if you sleeve a block, I guess must be overbored to some similar diameter to fit the sleeves, but then I guess in that case it is posible because block itself ( cilinder walls ) is not getting directly the explosions and direct heat.

This gets me to the next question. having 318s vs 340s, 383s vs 400s and 413s vs 440s... all this block families are different mainly due the diff bores... Does this mean all this blocks families got diff cilinder wall thickness making not posible to get the smaller block bore to the next bigger block bore ?

Maybe this seems kinda a stupid question, but, dunno, had to ask.

Very generally, yes the difference is the cylinder walls. There are other differences depending on which engine we are talking about

For example, using the 318 and 360 example you mentioned. The 318 has a slightly different driver's side motor mount ear setup. Not really a big deal but the 360 has a different main diameter as well as bore and a longer stroke than a 318.

I suppose you could sleeve all 8 cylinders and get whatever diameter is physically possible to stuff in with that bore spacing. But, and I am not a machinist, sleeving all 8 is not the average job. Be better off just buying the right block.

yeap, I'm aware about the diff mains and stroke of the 318 vs 360, but my main concern is at this moment just the bore and that size factibility on a 318, safely.

also I'm aware about some other casting differences all allong the years, but this is a diff stuff.

locally is very common sleeve 8 cilinders if needed to get back to life blocks to std ( for whatever reason )... my 400 was.

Being where you are it may very well be less expensive to sleeve all 8 than to import a block.

But my comment regarding sleeving all 8 wasn't so much "can it be done" but rather "unless done right it's not optimal for performance". Which one assumes if you are going for max bore size performance is the idea.

well hello Nacho, I've been wondering where you been. Likely sunning yourself on the beaches down there. It's 2 deg above zero here right now & that's Fahrenheight not celcius for you Metric guys + the wind chill (20 below)

OK, here goes:
Each engine size has its own block. That's why they have different casting numbers.

Mopar engines do not have good casting quality control, and they tend to have cylinder walls that are thin, but not too thin. So they will generally go 0.040 over, but there have been problems at 0.060 over.

This is why most here would say to sonic check a block before investing big money in it.

There are some 318s that will bore to 4.000, but not all of them. So sonic check's a must.

There are two exceptions to the above: Really early 360s, which were cast with 340 cylinder cores, and "could" go out to 0.100 over if you found a good block. I think these are pre '74 blocks, but others know for sure. The other is there were some industrial 413s that were built on blocks that had the industrial 426 casting number. I'd suspect that these could be bored out to 4.28.

Now on to sleeves: Sleeve material is stronger than the block's cast iron. The sleeve provides all the strength the cylinder needs, so if the boring bar breaks through in a few places it doesn't matter. Of course any material behind the sleeve provides extra strength and vibration resistance. Sleeving can distort the block if the machinist doesn't pay attention to the interference fit. At $100 a hole, sleeving all 8 is an expensive last resort that isn't done much.

Back to blocks, there are some other things to know:
1. New or old, the block quality is all over the map. It's tempting to think that mid-'60s blocks would be stouter, but that doesn't seem to be true. Any Mopar block can be good or bad.
2. In a test of many 400 blocks years ago, a well-known engine builder reported that many of the blocks had one or two holes that had thin spots, some as thin as 0.090" in unbored condition. So many 400 blocks would be very good with one or two sleeves, otherwise unusable.
3. Chevy bigblocks and 283s can normally take a 0.125" overbore, there are shelf stock 0.125 over pistons for 427s and 454s.
4. Ford Cleveland and Modified engines (351C, 351M, 400) have very thin cylinder walls and are done at 0.030 over without sonic checking.
5. With the availability of inexpensive UT thickness checkers, there is much less guesswork about what is a good block.
6. In general, it is much better to increase engine size by stroking than by boring. Thick, stiff cylinder walls do a lot to improve ring seal. Now that stroker cranks are a dime a dozen, overboring to increase engine size is out.

R.