239 crankshaft in 221 block

[Bored&Stroked]

I think you'll like the few extra cubic inches of a 239 . . . anda 4" Merc setup will be even better. From the outside - everything will look stock. Have the machine shop check the piston to head clearance - you might consider milling the heads just a bit to tighten this area up -- getting to about .040 clearance really helps these engines perform. With that said, you'll need to ensure that you have adequate clearance above the valves (which should be no issue with a stock cam). Where are you located?

 

[GOSFAST]

Post 6 have thrust welded up and finished .

Really don't recommend ever fixing the "thrust" flange area of any of these cast cranks, most times this repair will come back and "bite" you. Not worth the risk, not to mention the cost of the welding/grinding?

These 239" shafts are a "dime-a-dozen" in decent shape, we've tossed many of them over the years, have about a 1/2 dozen on the shelf here today still!

Thanks, Gary in N.Y.

P.S. If it's in the budget I would upstroke it and use the 2.000" Pontiac/Buick rod brgs! Just my opinion here

 

[rotorwrench]

Boring to 3 3/16" is approaching the limits for the 221 type blocks unless the Canadian version has thicker walls. Sonic testing wouldn't be a bad idea either just to make sure it doesn't hit water.