Just how much?

If you take a set of 4.125" bore sleeves you can safely bore them .030" over to clean them up. More than that and the O-ring grooves are getting thin. 6" stroke will clear easy with NO block clearanceing. The billet rods that I have a friend make in his CNC shop clear the oil pan rails of the block by .080" with a 6" stroke. So you could go 6.125" stroke easy and end up at 332 CID with no more work than a simple boring of the sleeves to get them to clean up and use some very short off the shelf Chevy 400 pistons. The only clearanceing work is a notch in each side of the sleeve for the rod to swing past. The rods would get very close to the oil pan rails on the block, but they will clear. At 6" there's no work, anything more and it takes a little grinding on the oil pan rails of the block. Mock up, mark the areas and grind. These sleeves are going to get to short in a hurry depending on your rod, piston and stroke combo, you need to support the piston at BDC, but just say for example a 6" stroke, the 8" long billet rod and there's lots of off the shelf pistons from a 400 Chevy to fit depending on your desired compression ratio. That longer rod keeps the piston higher in the sleeve at BDC for more support.

So a 6" stroke fits easy, an 8" long billet rod keeps the piston high enough and you have a huge selection of cheap and available off the shelf pistons to fit a set of 4.125 bore sleeves, or a slight overbore. You can have a 320 to 332 CID engine for very little work, no block machining and no clearanceing. In the future should you wish to bore the block you just don't have huge money tied up in the parts you won't re use, pistons, rings, sleeves and any boreing. It's going to cost about $400-500 for those parts that would wind up unused, just figuring $100 to bore and hone the sleeves, there's decent forged pistons for $60-$100 each and good rings aren't cheap. The cost of the stroker crank and connecting rods is the same, once they weld a crank it really doesn't matter how far you go. You can save some money on rods if you use a take out rod from another application, but they won't fit as nice and are not as strong as a good billet. Spend your money on good rods, go a little further on the stroke. You can keep a good rod angle in the engine at 6" stroke yet, once the rod angle gets to poor you're going backwards.

I had one togather at 6.5" stroke to see, well it only takes about a .250" deep notch in the oil pan rail to clear and the rods still clear the cam. I had read someone (our banned member) on YTmag claiming that it was impossiable to fit when someone had a crankshaft for sale. Well it's not only possiable, it's easy with use of the right parts. The-Man has a 6.5" crank to sell that is a very nice piece.

I need to add that it makes a difference how large of a crankpin or rod journal is used. For a given stroke, the rods get closer to everything in the engine the larger the crankpin diameter is. I like to use a 2" diameter crankpin, it's still strong enough and small enough to clear. The key is the rod cap angle, a rod with a straight cap will not clear things as easily as a rod with a canted or angled cap. ALso the larger the bore, the easier the rods clear the sleeve, the small bore sizes take a bit more of a notch to swing that rod past.

I make some sleeves from time to time that press in the bottom counterbore of the block, they will take a 4.28" bore easily. No O-ring groove, I just use some sealant on the bottom of the sleeve and I'll put a little fiber filler in the bottom of the block for added insurance. The fiber is easy to machine if a guy ever bores the block larger, it can be bored through without wrecking tooling and chiseled out if needed later. But it takes some work after installing the sleeves, boring the block with the sleeves installed and decking the top, then you have no sleeve protrusion to hold a head gasket so I use a copper head gasket and I cut o-ring grooves in the head and put a wire around the bore......it's all just more work and the average guy isn't set up to do has to pay for. So it only costs the difference of boring the block to put a large bore in.

I've got a motor for my WD45 to finish up someday. It's an early D-17 block with large mains and bypass oiling. 4.28" bore and 6" stroke for a 345 CID for the local 4 and 5mph "farm stock" pulling that I never get to anyway. I just got to busy with the super stock to finish it last spring and haven't had time for any extra shop projects since the snow melted. Everything's there, custom Diamond gas ported pistons, billet rods, Total Seal gapless rings. The machine work and balanceing is done, I just need to grind a notch in the sleeves for the rods to swing past, degree the cam and assemble it. If I get a chance I'll post some pictures so you can see how easy it is to clear the rotating assembly.




Edited by wi50 - 28 Aug 2013 at 9:48am

4.125 bore 6 3/8 stroke Ronnie shipman rods at 1.88 journal dont hit rail but pan needs moved down so it will hold more than 3 quarts of oil 341 cubic inches or the block bore is 4.5 with a 4.755 counter bore at top of block .Have a ring made for the 4.755 like m farmall builders do .buy a straight wall sleeve with a od of 4.503 knock it in. pin the sleeve like lot of sleeves are in motorcycle jugs drop the ring over sleeve add a 4.375 piston in it with 6 3/8 stroke be 383 cubic inches with no machining just honing.

Edited by jpankey - 31 Aug 2013 at 2:26pm