boring the 292 truck block to 4.00 inch diameter; using 256 merc crank with 3.10 stroke; using 6.252 rod length which yields 2.01 R/S.
This should produce a 311.6 ci displacement hence approximately 312 from a little bit different direction; also, this yields a Bore to stoke
   ratio of 1.29. what is best piston to use?

Good luck finding a block that will go that far, I think a ECK Block maybe thicker but I don't think it will go 4.0"

Sonic check the block to make sure it will go that far.  The pistons will probably have to be custom.  Since you know the other dimensions, you know the compression height needed.  A 4.00" piston should be very common.  Look through catalogs and email or call manufacturers to see if there is one that will work or can work with little modification.



Lawrenceville, GA

no block will go that far.it takes a good one to go to 3 7/8

57 Ranchero;

If you already have the Mercury crank, I can understand why you want to try to go this route. I chose a different approach with my 292 C2AE block; I bored it 0.060", used a 312 crank and had the rod journals turned down to 292 specs. Used C2AE rods and 312 pistons which had to be milled down about 0.063" (due to the longer rod length) to achieve 0 deck height. That comes out to about a 317 cu.in. motor....and it runs really good.

  Ron Lane,  Meridian, ID

57Ranchero.  I'd encourage you to read a thread from 4 months ago titled, 'De-stroked 292 Y-block'.  It delved into the idea of using a 3.10 Ford / Merc crank as you have suggested, maximum bore, rpm range, engine torque, etc.  Ted Eaton, Joe-JDC, Miker, John Mummert, and others made significant comments in the two page posting. 

Click the link below to access this thread from the Archive.
http://forums.y-blocksforever.com/FindPost136569.aspx

I think you'll find the read very informative.  


NoShortcuts
a.k.a. Charlie Brown
near Syracuse, New York

As mentioned, forget the 4" bore idea, not going to work!  Instead contact J. Mummert Machine re info on his just released 312 " conversion kit for 272/292 blocks..
N.B.- Rono, U errored, I think U meant to say the Main's were turned down to 292" size. Correct?  


Paul

I have a 292 truck block(1960) that is bored 120 thousandths in my 55 Fairlane and has standard 312ci pistons and rings on a 292 crank and rods runs with no problems. I don't know if this setup is abnormal or not, but in this case,it is working. What do some of you that have more knowledge of this think?

Bob, Yours can't be .120" over and have std 312 pistons.  Standard 312 is 3.80" which is .050" over 292.  .120" over 292 is 3.870" (.070" over 312).


Lawrenceville, GA

If I did the math right, on a 292" block that comes out @ 3.870" diameter. (as previoulsy noted)  As I understand it, on a block with little core shift that will work. Unfortunately, on quite a few blocks it will result in a near paper thin wall somewhere. The other negative is that in many cases, it likely does not allow enough wall thickness for any safe rebore... Anyone considering a rebore that big or bigger, should "definately" have the block sonic checked.  Keep in mind that the "experts" like Ted Eaton, & likely J. Mummert, when building a performance Y-Block, normally don't exceed 3.860" diameter piston size. That equates to a 312 + 0.060 size diameter..  On a 312 crank that results in 322".. IIRC, Ford only made pistons to .040 over for 312s. And that in a 292 block would equate to 306 cu " if I got it right? 


Paul