There is plenty of information on offset grinding cranks to 3.61 and using aftermarket H beam rods.  Apparently 3.53 is the maximum for standard rod journal? But this is all I can find. 

Please can someone enlighten me.

Thanks

Warren

Grizzly (Aussie Mainline)

Here are some links to past threads regarding offset grinding crankshafts.

http://www.y-blocksforever.com/forums/Topic2615-3-1.aspx

http://www.y-blocksforever.com/forums/Topic9269-3-1.aspx

http://www.y-blocksforever.com/forums/Topic18275-6-1.aspx

http://www.y-blocksforever.com/forums/Topic33348-5-1.aspx

http://www.y-blocksforever.com/forums/Topic55593-3-1.aspx

Using the search function will bring up more.

Lorena, Texas (South of Waco)

Sorry I should have been more clear. I was enquiring about stroking a 312 to 3.51-3.53. I have a 312 crank that is apparently 10 under and a 56 Mercury 312 that reasonably second hand but could be salvageable.

On John Mummert's site it quotes that  3.53 is as far as you can go with a standard size journal. Does this mean that you can use standard rods? (I'm guessing forged truck or Mummert performance I beam)

I have read the other links several times but seen nothing on this configuration.

Thanks

Warren

Grizzly (Aussie Mainline)

Doing the math, the 3.53” stroke is attainable on a good standard 312 crankshaft when cutting the rod journal size down to a standard 2.100” journal.  That will require a different connecting rod other than what was originally available for the Y engines.  If the crankshaft that is being used has been previously turned undersize, then the amount of stroke offset available for a given journal size will be less than this and still using the 2.100” journal as a starting basis.  As far as using stock Y rods and assuming you can get 0.060” undersize bearings, then starting off with a standard 312 crankshaft, the maximum stroke in this instance would be 3.46” when starting with a good standard crankshaft.

The smaller the journal size that's being targetted for, then the more opportunity there is for additional stroke offset.  2.00” journal sizes are common place for offset ground Y cranks while 1.889” for the rod journal sizes takes offset grinding to the next level.  With the 1.889” journals, the oil holes at the journals do have to be watched as they will have a tendency to creep too close to the journal edges and if the journals themselves are being widened to accommodate wider rods, then the oil holes themselves can become exposed at the journal filets or radius.

Lorena, Texas (South of Waco)