Quote:
Originally Posted by philipswanson
This is a new NOS block and I can't see boring it.
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It is all just choices in the end. If you want to increase the stroke of the engine, you're going to need new pistons . . . so they'll have to be custom in this situation. Also, you'll need to run the 21A or 91A rods that will fit through your bore - which means a 2" rod journal crank. A good combination would be a 4" late Merc crank - offset ground to 4 1/8" stroke . . . using the 2" rod journal.
Should be a fun project - once you get past the piston purchase (which will be a bit pricey - but not that bad). I'm not sure a 4.250 stroke crank will fit in it (from the perspective of the rods hitting the bore) - not sure there is an issue, but something that needs to be known. Of course there are many situations where one has to "notch" the bottoms of bores to clear crankshafts . . . just not sure if there is an issue in your case.
if you have any questions about anything, feel free to PM me.
Best of luck,
B&S