256ci ford 268ci ford interchangeable

[mic-t]

will a 256ci ford bolt up the same as a 268ci ford or Vic versa

 

[Bern]

Yes

 

[mic-t]

well that opens up a lot more possibility's.

 

[Destroked 450]

They will inner change, but you'll notice a loss of torque with the shorter stroke 256

 

[mic-t]

i would be going up to a 268 . So I am assuming it would be a gain . do you know if the 268 is any longer so i can use the oil pan off the 256.

 

[Bern]

The cylinder blocks are dimensionally identical.

 

[mic-t]

awesome thanks for the info

 

[Destroked 450]

Different crank and pistons otherwise the same engine

 

[sunbeam]

The last 2 or 3 months of 6600 production ford used the 268 instead of the 256.

 

[Bern]

Same with the 7600/7700. And the 5600 jumped from 233 to the 256. They were called the blue power specials.

 

[65intheBurg]

I just went through this with some help from destroked. My 5610 (256CID block with a 4.2 stroke crank)
crank was changed some years ago with a 4.4 stroke crank and shorter pistons. But I didn't figure this
out until I assembled the block with longer pistons to match a 4.2 crank. Longer pistons with longer
stroke cranks results in the piston hitting the head. I ordered shorter pistons that match the 268 CID
engine and 4.4 crank and everything is fine. The crown of the piston extends past the block by .010 but
the head gasket is .050 thick so I am OK.
The point is .....the 256 and the 268 blocks are the same....

 

[Bern]

Spec for piston protrusion on a NA (naturally aspirated) block is .011 - .023 inch above, so you're good to go.

 

[65intheBurg]

Yes it is, thanks Bern. But it still makes me nervous, that's not much room between the piston and the head.

 

[Bern]

As they say, a miss is as good as a mile.

To give you an idea of just how close the tolerances can be, more than once I've pulled one of those engines down for a rod knock. Sometimes the cylinder with the bad bearing will also show signs of one or both valves kissing the piston.

 

[Destroked 450]

.011-.023 piston protrusion with a .050 head gasket isn t bad
My 5.9 Cummins specs .019-.028 with allowances up to .032 using a .051 head gasket
I had to use a .010 thicker gasket due to the block being decked .010 with piston protrusion at .037