Technical Sleeve it or bore it...

I got a 59 flathead block I'm getting ready to send off to the machine shop and all the cylinders are at 3.30X".
My question for everyone is should I be born g this thing to 3 5/16"-3 3/8" or should I sleeve it and get it back to a stock size bore??
It's getting a Merc crank and 29a rods just not certain the large piston size is the right answer. Would I be able to bore it again??
Thanks for the help!!

 

I would bore it to 3 -5/16, with the Merc crank it will be 276", good combo.

 

But Marty that only gives him 12 1/2 thou to clean and true the bore. Is that possible or do-able? He could go 3 5/16 plus whatever oversize the machine shop needs to give him a good bore.

 

Sonic test & pressure test first. Offset grind the merc crank to 4 1/8 bore what it needs 21A or 91A rods & now you have a great engine.

 

Ross Pistons, made us a couple of sets 3-5/16 plus .030. Any competent machine shop could run a dial bore guage through the bores, and tell if it will clean up at 3 and 5.

 

Do the smallest over bore that will clean it up.Remember you have 70 years of erosion working from the other side of the cylinder.

 

Trey, I have a 8BA punched out to 3 3/8" it has many thousands of miles with no problems. I have noticed it gets 10-15 degrees warmer on long hills but never overheats. If you go that big be sure to check piston to head clearance. The head overhangs the bore and can hit the domed piston. Have fun,Chuck

 

Make sure rings are available before you start anything. Pistons can be made any size; for me it’s the rings.

 

Why worry about a rebore are you going to drive it over 100.000 miles?