As Bill and Rono bring up, going past a standard 292 bore gets the 272 block really on the thin side. Sonic testing the block will at least show where the core shift is located which can help the machinist in moving the boring bar to help equalize the cylinder wall thicknesses. Here are some past threads on the subject.

http://forums.y-blocksforever.com/FindPost18677.aspx

http://forums.y-blocksforever.com/FindPost41511.aspx

http://forums.y-blocksforever.com/FindPost41541.aspx

http://forums.y-blocksforever.com/FindPost39639.aspx

In looking for the original post that had the sonic sheet for a 272 that had been bored to a standard 292 size, I find that it must have been on the old site as it’s no longer available. With that in mind, here's another sonic sheet for an over-bored 272. The bore thicknesses highlighted in red do make this block questionable for use. Had the block been sonic checked first and then offset bored to compensate for core shift, then the block could have still been more suitable for use.

I’ve refrained from using ceramic coatings on the street engines simply due to the hours or cycle times in which the coatings are good for. If those coatings start to peel or lose their adhesion properties after an extended period of time, then that debris will damage the cylinder walls and rings.

Sleeves properly installed should pose no problem but as mentioned, the cost is prohibitive when attempting to do all eight cylinders. Not all machine shops are capable of properly installing sleeves so be cautious when getting that operation performed. Using used pistons is fine as long as they are in ‘like new’ condition but unless they are low mileage, that will likely not be the case. The money that is spent to sleeve eight cylinders in a block to use a set of old pistons is much better spent on a set of custom pistons that are sized to fit the next oversize of bore or ring sizing availability. And with custom pistons comes the ability to use a more modern piston ring design which helps with both the power and efficiency of the engine.

The accepted minimum cylinder wall thickness is 0.100”. Boosted or high horsepower applications will typically require more than this.

As Bill brings up, simply boring the block for big bore sleeves destroys the built in support between the decks and the main webbing. To simply sleeve the block for the sake of sleeving gains you nothing in cylinder wall wear or block integrity. In the grand scheme of things, any installed sleeve in an iron block actually weakens the block integrity to some degree as the original cylinder wall thickness is compromised.

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Sleeves for the Ford Y-Block engines are reserved simply for those cylinders that need repairing due to some kind of damage. If the original cylinder wall is severely damaged to the point where the ring wearing surface is exposed to coolant (cracks, holes, etc), then even a sleeve may not be an adequate repair due to the head gasket design on the Y engines. Most engines have a round sealing ring on the head gasket that can catch the top of a sleeve for sealing purposes but the unique design of the Y combustion chamber requires the use of a head gasket that does not fully seat on the edge of the bore. If there’s a chance for coolant seepage between the sleeve and the original cylinder wall, it typically happens because the head gasket is sealing on the deck and not the edge of the bore.

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It was my 4” bore engine that was sleeved in such a manner that the original cylinder walls were removed to accommodate the thick wall sleeve installation. While the engine made a tremendous amount of power, the block did take a twist early on which allowed coolant seepage between the decks and the installed sleeves. Furnace brazing the block may have helped with this but that operation is not available in my part of the country.

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On a lesser horsepower engine, this problem would have still occurred but simply would have taken longer for it to take place. An example I have is a 347” Y here that was fully sleeved and it did manage to run for awhile before coolant seepage came to the forefront. In examining the water jackets on that engine, some of the sleeves did break through the original cylinder walls which reduces the block strength and also gives the coolant a path to the top of the deck when conditions are right. That engine will be put together again as a smaller bore engine without sleeves.

That would be an affirmative“Yes”. Ford 292/312 blocks using big bore sleeves tend to crack the decks between the cylinders as well as have water seepage between the sleeve and the deck into the combustion chamber where the head gasket is not residing on the edge of the cylinder itself.

Not many 292 blocks will bore out to the 4+” bore required for big bore sleeves without breaking through at least a part of the cylinder walls. Core shift within the block has a lot to do with how severe that cylinder wall offset will be and the subsequent complete boring away of part or all of the cylinder walls. If the cylinder head had a combustion chamber that was fully within the bore confines, then a head gasket with a perfectly round sealing ring could catch the top of the sleeve and minimize the water leakage issue regardless of what was going on between the sleeve and what was remaining of the existing cylinder wall. Granted that this would not be a total fix but this would go a long way towards addressing the water seepage issue with big bore sleeves.

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Cylinder wall integrity has much to do with making the big horsepower numbers. Minimal cylinder wall thickness simply promotes cylinder wall flex which in turn costs some serious horsepower as well as setting the cylinder wall up for an early failure. It’s for this reason that cylinder walls are intentionally left at smaller bores so that the cylinder walls can be thicker in boosted applications. A case in point is when building the engine for Randy Gummelt’s rear engine dragster, the bore size was intentionally left at 3.800” bore rather than the 3.860" bore used on a serious normally aspirated Y engine build.

That’s where furnace brazing comes into play. Unfortunately that’s not available in my area. I did try soldering both ends of the sleeve from the water jacket sides and putting a layer of resin at both the upper and lower portions of the bores within the water jackets but that also failed. For what I'm doing, a 375 incher is as big as it gets and still be a reliable combination.

Welded cranks had a high failure rate with the life expectancy also being on the short side. Porosity, flaking off of weld, bearing wear issues, and breaking crankshafts are just some of the problems related to the welding up of crankshaft journals to increase the stroke. The advent of aftermarket cranks in both the forged and cast versions for the more popular engines has made the welding up of crankshafts for stroke increases a very unpopular option.