Can a 348 have larger sleeves installed to make it 409 size bore?

1964SuperStocker

Well Known Member
Supporting Member 3
I know its absolutely nuts but I read a posting this weekend where someone claimed to get 409 pistons in a 348 block. I mentioned that was probably a bad idea and to just put a bigger crank in. It did lead me to thinking about the future when 409 blocks are already in the $2500-4000 range and getting harder to find. THE QUESTION IS: #1. Can a 348 get 409 size sleeves in it and accomplish more cubes? #2. If it can be sleeved to 409 size bore then can it also be stroked out as well to reach the 470's-480 cubic inches? As the actual 409 blocks become more scarce and people want more cubes. Can I take a cheap and plentiful 348 block and install sleeves (not cheap) to get the desired larger cylinder bore of a 409 and then stroke that to get 470ci+ out of a cheap block? Has anyone done it? I'm not worried or thinking about the notches in the block because sleeves would take those out anyway. Anyone have pictures of their blocks before and after sleeves 348 or 409 from above and below? I have 2 348 blocks that are perfect externally but need 2 sleeves each, just pondering. :rub
 

427John

Well Known Member
There was an article in one of the early 60's Hot Rod yearbook annuals that described the build process of one of the first 400 cubic inch small block chevys.They bored the cylinders completely out of it and then furnace brazed new sleeves into it,so I would say the answer is yes,but with this method in this day and age the question of would it be practical I think would be no.I have heard that some 348's can be bored this far but wall thickness is thinl,I've also heard that sleeves themselves are made from a denser higher quality material than cast in cylinder walls and can stand a thinner wall thickness,so maybe boring to paper thin walls and pressing sleeves in and boring to 409 size is a possibility,but it sounds like a very expensive experiment unless you have stuff to do it yourself.
 

409gang

Well Known Member
Supporting Member 1
I know its absolutely nuts but I read a posting this weekend where someone claimed to get 409 pistons in a 348 block. I mentioned that was probably a bad idea and to just put a bigger crank in. It did lead me to thinking about the future when 409 blocks are already in the $2500-4000 range and getting harder to find. THE QUESTION IS: #1. Can a 348 get 409 size sleeves in it and accomplish more cubes? #2. If it can be sleeved to 409 size bore then can it also be stroked out as well to reach the 470's-480 cubic inches? As the actual 409 blocks become more scarce and people want more cubes. Can I take a cheap and plentiful 348 block and install sleeves (not cheap) to get the desired larger cylinder bore of a 409 and then stroke that to get 470ci+ out of a cheap block? Has anyone done it? I'm not worried or thinking about the notches in the block because sleeves would take those out anyway. Anyone have pictures of their blocks before and after sleeves 348 or 409 from above and below? I have 2 348 blocks that are perfect externally but need 2 sleeves each, just pondering. :rub
I don't think so as there would be nothing left to hold the deck down, You would have to bore the block larger than 4-5/16" just to install the sleeve. Lamar Walden told me it is not a good idea to put 2 sleeves next to each other on a 409 block as it will lift the deck but that is probably on an all out race motor. I don't think Lamar played much with stock 409's Lol. Like 1958 delivery said you can already make a 348 plenty big (440) just with stroke and a .060" overbore.
 

427John

Well Known Member
A 4.25" stroke crank in a 348 block bored to 4.25" which I hear is a possibility in a few 348 blocks with a sonic map and some offset boring will give ~483 inches,so I wouldn't rule out seeing one sooner or later.
 

1964SuperStocker

Well Known Member
Supporting Member 3
A 4.25" stroke crank in a 348 block bored to 4.25" which I hear is a possibility in a few 348 blocks with a sonic map and some offset boring will give ~483 inches,so I wouldn't rule out seeing one sooner or later.
I've already purchased a 4.25" crank to do some test fitting. My 4 inch stroke crank only needed the counter weights turned down a little but otherwise the only block issue was the type of nuts I used on my Rods. I had to clearance the block for those but it was minimal. We will see, I'm just trying to learn as much as I can about these motors.
 

1964SuperStocker

Well Known Member
Supporting Member 3
Unfortunately many of us will die before the world runs out of 409 blocks.
I look at it more like a supply and demand issue. Few people are excited about 348's nearly as much as 409's because the beach boys never made a song about a 348. Considering the number of people going after these motors in the last 5 years, I would say the increase is significant and the next 5-10 will only explode further. 409's go for way more money than 348's but you can build some impressive power from a cheap 348 block. When the initial money up front for a 409 is normally double that of a 348 I would say if you can go with a cheaper block then spend you money on better parts, then you are miles ahead. If I would have bought a 409 block to build, I wouldn't have spent more on the block then on a block and all of the machining I had done to the block.
 
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