I remember someone telling me that machining of the block isn't needed to do a 355 stroker, just different pistons, rods, and crank.

Is that true? Because it didn't seem right to me.

And if you're getting machine work done for a 355, why not just go to a 383?

 

355" is a 350 bored .030", stock 3.48" stroke.

 

You need to bore the block .030 over. So to answer your question machining is required plus you will need to have your rotating assembly rebalanced if you decide to use your stock rods and crank.

 

You need to bore the block to 4.030".... that's what makes a 4.000" bore 350 into a 355. You don't have to do any other machine work to the block, like clearance the oil pan rails for the larger crank throws of a 383. A 355 can live with the stock crank and stock rods.

When you go to a longer 3.75" stroke x 4.030" bore to build a 383, you've got possible clearancing for the crank, some pounding on the oil pan maybe... you might want to convert to splayed 4-bolt mains if you are looking at big HP, you probably want to look at 5.85" or 6.00" rods instead of the stock 5.7's.... a lot of potential differences.