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I have been looking around at stroker specs and Ive noticed they all say they were bored .030 over is there any reason for this and is there anything I need to be aware of .I was going to use a 3.850 crank 5.955 rods and 302 piston per summits strokers wild build of the bottom end and is there a difference between 302 piston and a 351w piston
 

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The difference between the two pistons is the pin locations. One is higher up(towards the top) probably the 302 piston.
I'm not an expert so maybe someone else can shed more light on this. I do know that you need to use the 302 pistons in a 351 stroker build.
 

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Where's Woody when you need him. He sells this stuff and knows all about it. Seems like a real good guy.

The .030 over is just to clean up the cylinders on a used block. Not a stroker thing. A rebuild thing. It will give you a few more cubic inches. An example is a .030 over 302 would become a 306 and a 351 becomes a 357.
 

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I think the stroker kits are based on the .030 over sized pistons because most people are building their engines from a used block and normally you would go .030 over to clean up the cylinders...The difference between a 302 and a 351 piston is the pin hieght or "compression hieght"...By using different length rods and pistons with different compresson heights you can come up with lots of different options to squeeze a longer stroke into a particular block with a particular deck height.
 

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The 393 stroker uses the 302 piston - - thats the beauty of it - - the parts are inexpensive. One thing to be aware of is that you may need to run a dish piston on the street - the long stroke raises compression quite a bit.

302 pistons are available in any bore. The.030 over is just a "convention" used to describe the kits. I (or anybody else) can get them in standards, .020s, .030s, .040s, .060s.....
 

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302 pistons have a compression height of 1.600. 351W stock pistons have a compression height of 1.774, IIRC. The 393 uses 1.600 compression height pistons...which just happened to work out to be a 302 piston, more or less. That's why a 393 is so popular. Stock rods, stock 302 pistons and a chinese crankshaft...very cheap & easy to put together on a budget. The reason most kits show .030" bore is that most of the time if you are replacing the pistons, crank, rods anyway...it's a good idea to go ahead & bore the block to square up the cylinders. Usually they're out of round & tapered after a few hundred thousand miles, which affects ring seal and ultimately power. There is also the .040 and .060" sizes for those of you who have a block that won't clean up at .030" (like mine). Mine BARELY cleaned up at .060" and it had never been rebuilt. I imagine it smoked a little...
 

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Ford Racing builds 392's (same as 393) in new blocks. 4.030 bore. Its not just for rebuilds. Probably because of popularity, availible parts, and cubes. Oh, and some nice power.
 
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