250 crank, 200 rods...in a 200 block?

[73GreenMachine]

After finding out that my motor has some bottom end issues(I just finished rebuilding the motor) that appear to be piston related(cracked piston or gudgeon pin problems), I have decided to switch my 200 pre crossflow to a 250 by switching over the crankshaft. I have heard that you can build a 250 with 200 rods and that they rev better or there is some other advantage to it. Is it still possible to do this inside a 200 block or will my pistons stick out the top? Oh yeah and what is the part number for the ACL pistons that you use for this conversion? Are there any other improvements that I should do to the bottom end while my engine is apart(for the second time.. )?
73GreenMachine.

 

[DYNOED250]

hey have u ever wanted a x flow?... im fairly sure aslong as youre 200 is a tall deck motor u can do it.. it wont spin as easy as a 200. but the torque will be a nice increase

 

[TCSTEVE]

Greenmachine, yes it can be done theyre are 3 different pistons from acl for the 200 rod conversion. A standard sort of piston possibly standard bore. A 20 thou flat top bout 9.6 comp and a race flat top that gives you high 11 maybe 12.1 comp ratio with the 200 rods
They have them for your motor and the Crossflows but they are 20 thou over and come with rings.
Nasons are a good place to get your bits and if you give them love you might get trade. They stock most stuff. I got new oil pump,water pump,crow timing gear/chain,crow hardened dizzy gear,gaskets etc.
My flat top acls are 20 thou over and cost my $300 :roll: Got bearings and cam from them too. Good Stuff, Steve

 

[73GreenMachine]

Do the 250 and 200 have the same block? Ie is their bellhousing pattern the same. I think I read that the deck height is different, but is that the only real change?

 

[addo]

The 71DA (or is it D1DA?) and up 200s are the same block as 250s. Different crank, rods, pistons.

 

[73GreenMachine]

The 71DA (or is it D1DA?) and up 200s are the same block as 250s. Different crank, rods, pistons.

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Its 71DA, so I should be fine. Thanks for the info.
Plans are a 250 crank fully reground,rebored and reconditioned 250 block, 200 rods, custom ACL pistons (9.6:1 compression) 30 thou over, powerbond street balancer, EB flywheel and aftermarket clutch, full engine balance.
Now, time for another $1k engine rebuild and over 110rwkw with a log intake 250!