Where do you guys see the picture? I'm not getting one here.

Rowen
55CV
Woodland, Ca

Click on the IMG icon.  To ask another question, it could not be .060 over for either a 292 or 312 and be 3.840 bore.  If it is 3.840 bore and ECZ(312) block, then it can't have either .060 or .090 over pistons, so it has to be a 292 + .090 to be 3.840", which gives his cubic inches at 305.74 cubic inches.  Yes, a bit confusing.  Joe-JDC

JDC

He says it has ECZ main caps, but assumes it is a 292 bored .090". I go with the theory that it is a 312 bored .060. While it is still open I would measure the bore and stroke. 

Don't even see a IMG on my I-phone. Too bad, I love me some crown Vic's!

Rowen
55CV
Woodland, Ca

We had to put tubes in the tires 'cause being true spokes, they like to leak. The tubes solved the problem.

You could be correct................060 upside down reads .090.
But when you measure the piston or the cylinder wall and get 3.84" then
it must be .090 over..............right ?

.060 does not look like .090 upside down.  The dot would be in an incorrect position to confuse that.  if it shows .090, then it is .090 relative to something.  If there is no dot and we're just adding it in this conversation because we all know that it should be there, then, sure it can be confused.

Since the block has ECZ caps, it is a 312, possibly with .090 over 292 pistons, if it does measure 3.84", that have been clearanced for a 312.  Maybe 292 pistons of that size are already clearanced for 312 out of the box, since they are .040 over 312.


Lawrenceville, GA

Correct, the dot would indicated the correct size.
To tell the truth, I really don't care if is .40,.60 or.90 over just
as long as it gets up and runs down the road to shows or to 
Detroit for the Dream Cruise this summer. Which I've been to 
a few times in a different car, one with a blue bow tie on it.

Volume of a cylinder is :
pi x r^2 x h
pi = 3.1415
r^2 = 1/2 the cylinder diameter, squared
h = stroke which for ECZ is 3.44
3.1415 x 3.6864 x 3.44 = 39.839 Cu. In. Per cylinder. So, multiple by 8 cylinders is 318.7 Cu. In. Congrats, you have a mopar 318. Lol.

Tim.  1957 ECZ 6015-C engine blocks were factory machined as either 292 CID or 312 CID depending upon the main bearing caps for the crankshaft used.
ECZ 6015-C engine blocks with ECZ main caps have a 312 crank and were factory machined as 3.800 bore for a 312 CID
ECZ 6015-C engine blocks with EBU main caps have a 292 crank and were factory machined as 3.750 bore for a 292 CID

With your main caps showing ECZ, it is most likely that John (Hoosier Hurricane) is correct and that your pistons are .060 oversize with a cylinder bore of 3.860

Unfortunately, there are some off-brand piston suppliers who supplied some crazy oversize pistons for 292 y-blocks that read .080.  I've seen these.
IF they supplied .080 oversize 292 pistons, they may also have supplied .090 oversize 292 y-block pistons.

Originally, the difference in a FoMoCo 292 piston and a FoMoCo 312 piston was in the piston skirt.  The skirt of the FoMoCo 292 piston would not work with the longer stroke of the 312 crank.  That said, the skirt of a 312 piston would work with any appropriately oversized 292 cylinder overbore.

Some 'off-brand' (my term) replacement piston manufacturers MAY DO some 'different' things to fit as many applications as possible and reduce production costs.
Example:  they could use the 312 skirt design, the common 292 / 312 piston pin compression height, and simply machine the piston diameter and piston ring diameter grooves for 292 + .020, .030, .040, .060, .080, or .090 oversize dimensions.  
The result of this is that 292 + .080 piston can be used for 312 + .030 bores, and 292 + .090 pistons can be used for 312 + .040 bores.
 
An ECZ 6015-C engine block with ECZ main caps and oversize 312 pistons stamped .060 that measure 3.860 will displace 322 cubic inches
An ECZ 6015-C engine block with ECZ main caps may have off-brand oversize pistons stamped .090 that measure 3.840 will displace 319 cubic inches 

Click the link below to see John Mummert's web page for the engine block identification info.   I have cited and the second link below for JM's displacement chart for bore stroke combinations and the displacement that they yield.

http://www.ford-y-block.com/Block%20identification.htm

http://www.ford-y-block.com/displacement.htm

The off-brand piston manufacturers are the source of this confusion.  Measure the bore size you have to know what the bore you have with your 312 crankshaft.
Hope this helps!  



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