| vacaville john | -- 06-04-2012 @ 2:20 PM |
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I have a 1941 flathead 221ci. with aluminum pistons and steel sleeves. Can this engine be bored or do they normally just replace the sleeves. If it is bored what would be the maximum overbore?
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| supereal | -- 06-04-2012 @ 2:38 PM |
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That engine should be bored with the sleeves in place. Many blocks were sleeved because of defects in the block. The cylinders should only be bored enough to clean up any wear problems. You will need oversize pistons and rings, and if you go over .060, it will require special parts. A competent machine shop will measure the bores for taper and recommend the correct size. After boring, the cylinders are honed to the final size.
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| oldford2 | -- 06-04-2012 @ 2:57 PM |
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I would not bore the sleeves. They are only .042 thick and if you bore .060 over, the wall thickness would only be .010!! These engines were built with sleeves, not to cover defects. The sleeves are very difficult to find. If you find some you could re-sleeve it. Not an operation to try if you have not done it. Requires a special sleeve puller. I would pull the sleeves and inspect for defects. That would leave a bore of 3.146. Then bore to 3.188 where you can find pistons for it. At one time you could pull the sleeves and pistons were available to fit the bore (3.146??) but they are long gone. Always bore to the minimum. Bore size doesn't add appreciable power, stroke does. Boring steel is a lot different than boring cast iron. Just my opinion. John
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| kubes40 | -- 06-04-2012 @ 5:15 PM |
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Are the sleeves hardened? If so, your options are reduced. I have found hardened sleeves in a couple of my blocks and had to choose between grinding them or pulling them out and boring the (naked) block. It is VERY difficult to bore hardened steel to the depth required. Not impossible, but very difficult. Most shops are not equipped with the correct tooling and / or the knowledge to do so. I have bored many a "naked" block with no problems. From numerous horror stories I've heard, apparently I have been lucky. If you decide to have the sleeves pulled and bore the block, heed the previous advice and go as little as necessary to clean up for an available piston size. Unless you can replace the sleeves yourself, the cost of having a shop do it is quite a bit more than boring. Although I have numerous sets of sleeves and the KRW tools to remove and install, I have yet to re-sleeve an engine. To me, it is simply not worth the effort. This message was edited by kubes40 on 6-4-12 @ 5:19 PM
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