Here are links to a prior thread discussing strokers and offset grinding.  Doing a search on this site for offset grinding or stroker cranks will net some more information regarding the subject.

http://www.y-blocksforever.com/forums/Topic27324-3-1.aspx

http://www.y-blocksforever.com/forums/Topic27324-3-2.aspx

Thanks for the ref. to issue 66.  My stack doesnt go back that far so will order it with the subscription renewal.

This probably isnt going to happen, but it would be great if I could find a 2.10 big end rod the same length as a 312 rod that uses a proper size bushing.  Then a replacement flat top piston would be very close to the right position.  My problem is not knowing the options in rod lengths and their piston pin diameters, plus the same with the pistons.  I've tried pulling up some of the sites of makers referenced by Ted in one of the previous threads but havent been able to get the information, at least not yet.

Edit:  Finally have a number.  Scat -2-350-6250-2100 .  6.250 L, 2.10 journal, 927 pin, ARP8740 bolt.  $450.  With the length being only .002 shorter than the 312 rods, the piston location should be very close to even with the deck if my thinking is correct.  Now need to find something similar that is about $100 less.

What about honing the small rod end for a Ford bushing, or would it weaken the rod too much?

Good point. 

If you’d like to play with other compression height (CH) values, here’s the basic math formula.

CH = Deck height - (stroke divided by 2) – (rod length) – (amount piston is in the hole)

I havent given the block a check yet to see if it has previously been decked, but assuming it has not, and that it will have a .005 cleanup, is .015 too much to take off an old NOS flattop piston, or, what is the max. safe limit for material removal from the piston top?

Mike

Then the 9.750 figure must be after decking.  I had to deck the block that is in use .028 to get .004 in the hole.  There was align honing, plus the rods being resized made them .004 shorter, all added to the shorter(?) comp. height piston, left the piston .032 down.  With 9.775 being the stock height, there is a lot more wiggle room and theoretically decking alone could have the piston at zero.  I've seen deck heights referred to before, but didnt have reason to remember them, so thanks for the figures.

We made the pistons that way so you could start with .030" under crank and still end up with standard rod bearings.

Pistons will also work with 292 crank offset ground to 2.00 journal.

They will also work with 312 crank offset ground to 2.00" journal and 3.61" stroke and 6.125" rod

Putting chev pins in a Ford piston is no big deal.  They only need honed .015, and the pin lock grooves are already in the pistons.  The chev pins are too long, but you can even grind them by hand on a bench grinder if you have to.  When I did mine I was still working, so I used the company's wet chop saw with the adjustable stop.  The rods need to be narrowed on the big end to Y width also, can be done in a lathe, mill, or on a surface grinder.  Clevite even makes a sbc rod bearing that is narrower than stock to clear a larger radius, so you don't have to narrow the bearings to fit the Y journal.  You're right, too much custom machining if you can't do it yourself.  How about a set of Mummert's replacement steel Y rods? 

Charlie, as I said above, the chev is only .015 bigger, so a bushing in the chev rod would only have .0075 wall, I don't think it would hold up.

Charlie: I'm puzzled why you needed to trim your pistons. They should have been .020-.025" in the hole.

Mike, another issue is the 292 piston skirt length. They will hit the crank counterweights. 292 pistons will hit a 312 crank with 312 rods.

Thought about Charlies busing approach, using a thicker bushnig to press in and then hoing to fit.  But such a bushing probably doesnt exist.

DID NOT KNOW of the skirt interference John M.  It must be in the area of the eliptical cut out.  I took a new 312 std piston & set it beside 2 .40 and a .060 OS 292.  The 292s were approx. .043 taller at the bottom of cutout compared to the 312.  Then the same comparison done with a .060 os 292 which has some design differences, and found it was shorter than the 312.  Too bad there are only 7 312 std and one .060 oddball.  But the odd ball could be weight matched to the others (it is 6 gms heavier than the lightest standard), & put under a chamber that  cc's the largest.

John's replacement 312 rods would be preferrable to rebuilding, but that would bring back "heavy decking", which made me pretty gunshy the first time.

Sorry about all the typos.  Typing with the left hand only while filled up with narcotoc is a chllenge.

Yes, the 292 pistons hit in the curved portion at the bottom of skirt. I have used a 7" diameter cutter with piston on its side to make them fit but it is a little scary. Since it's Halloween that might be okay.

I'll buy a set of John's 312 rods, and save for the pistons.  Found that his forged pistons are something like .015 taller which is GOOD.  The domes give a world of options on CR too.

Thanks to all you guys.

Mike