OK, I'm now conviced my supposed "312" is a 292. So, does anyone know what the compression ratio of a 292 bored 0.30 over using the big valve heads would be?

...Now that I think about it, what is the bore and stroke of a 292?

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People should not be afraid of their government, a government should be afraid of the people.

--Alan Moore

Go here to look up info

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

Ol'ford nutCentral Iowa

56 Vic w/292 & 4 spd.

Unfortunately John’s chart only gives the cubic inches for what happens when overboring and/or stroking.  There are at least three different big valve head castings with the advertised cc’s being between 69 and 82cc’s.  I'll add at this point that the advertised cc’s is the best case scenario and many times the actual cc’s will be somewhat larger that these.  To accurately determine the compression ratio, the head cc’s and where the piston resides in the block needs to be known.  Add to this that the head gasket manufacturer and composition plays into this along with how much the heads have been milled.

 

Here are some of examples of how the CR can change with the various heads and/or machine work.  A best case 292 at 0.030” over with the flattop pistons at zero deck and a set of big valve ‘G’ heads milled 0.020” with a Best Gasket head gasket will be right at 9.0:1CR.  Using a set of  big valve ‘113’ heads on the same combination that are nominally larger than advertised to begin with and only milled 0.006” will give a CR of 8.15:1.  Using a set of big valve ‘471’ castings and assuming they have the stock 82cc chambers (could be nominally larger) will drop the compression ratio to 7.6:1.  Dropping the piston from zero deck to 0.027” in the hole and the compression ratio automatically drops another half a point or what was a 9:1 engine suddenly becomes an 8½:1 engine.  Put  a piston with a 10cc dome back in the engine and you can pick up just slightly more than a full point in compression increase so there are several ways in which to manipulate the CR to get it exactly where you want it.

Lorena, Texas (South of Waco)

I just recently put a 292 together and carefully calculated my compression at 9.1:1. This is with 3.75 bore stock piston (not stock replacement, they give less compression) To get that high I shaved the heads .020 and decked the block .010. I also used a shim head gasket so my clearance is real tight around .035.. This motor with a blue thunder intake and a 230@.050 cam made 298 horse at 5500 rpm

298 hp out of 292 cu. in.  Nice work!

Mike, located in the Siskiyou mountains, Southern, OR 292 powered 1946 Ford 1/2 ton, '62 Mercury Meteor, '55 Country Squire (parting out), '64 Falcon, '54 Ford 600 tractor.

Very respectable indeed!

   God Bless.   Tim                           http://yblockguy.com/

350ci Y-Block FED "Elwood", 301ci Y-Block Unibody LSR "Jake", 312ci Y-Block '58 F-100, 338ci Y-Block powered Model A Tudor

tim@yblockguy.com  Visalia, California    Just west of the Sequoias

Why dont you start a thread with a few more specifics on the build.  Some of us may have some questions.  298 hp at 5500, cool.

Mike, located in the Siskiyou mountains, Southern, OR 292 powered 1946 Ford 1/2 ton, '62 Mercury Meteor, '55 Country Squire (parting out), '64 Falcon, '54 Ford 600 tractor.

An article with all the details will be in the next issue of YBM