Crankshaft

Can you stroke a stock crankshaft to what you want.

its called offset grinding... and yes to a point. you can offset grind up to .3 off the rod journals giving you .6 more stroke... which on a 460 crank would come out to be 4.35" but there can be oiling issues so its not really recommended... the 429 crank works better when offset ground... 4.19"

darrin1999 wrote:its called offset grinding... and yes to a point. you can offset grind up to .3 off the rod journals giving you .6 more stroke... which on a 460 crank would come out to be 4.35" but there can be oiling issues so its not really recommended... the 429 crank works better when offset ground... 4.19"

think you got to much stroke there.. your .6 is like 2X to much, then the 4.35 is only .5" (1/2inch) more stroke not .6"

The 4.14/4.15 offset grind is the most common offset grind done to the stock crank. This uses common off the shelf pistons and rod combos. Stock stroke is 3.85" and you go from a 2.5" rod journal to a 2.2" rod journal, 3.85 + .3 = 4.15". If you want more, then a Scat, Eagle, etc.... crank is needed.

when you take the .3 off the journal that brings the piston .3 closer to the top of the cylinder... but it also brings it .3 further down from the top on the down stroke... thats why the combined difference is .6 instead of just the journal difference of .3

I was told 4.15 is the max stroke on the stock cranks unless you went with undersized bearings and then only very marginal gains.

darrin1999 wrote:when you take the .3 off the journal that brings the piston .3 closer to the top of the cylinder... but it also brings it .3 further down from the top on the down stroke... thats why the combined difference is .6 instead of just the journal difference of .3

that say's you never done it or seen it done, just doesn't work that way

DanH wrote:

darrin1999 wrote:when you take the .3 off the journal that brings the piston .3 closer to the top of the cylinder... but it also brings it .3 further down from the top on the down stroke... thats why the combined difference is .6 instead of just the journal difference of .3

that say's you never done it or seen it done, just doesn't work that way

although you take all the .3 off of one side your journal centerline only moves .15. so you gain .15 at TDC and .15 at BDC.

darrin1999 wrote:when you take the .3 off the journal that brings the piston .3 closer to the top of the cylinder... but it also brings it .3 further down from the top on the down stroke... thats why the combined difference is .6 instead of just the journal difference of .3

NOT true at all...!
"Diggendeeper" is totally correct.

When you offset grind .300" off the journal you are moving the CENTERLINE of that journal only .150" so, the piston will rise .150" more and go .150" farther down the bore. The stroke will be increased the .300" only.
That would require a perfect stock 460 crank to start with so, .290" stroke increase is the norm with a 2.200" journal. A 4.090" stroke with a Pontiac 2.250" rod journal; A 3.970" stroke with a Chrysler 2.375" rod journal; are the other normal offset grind specs.

sorry for the misinformation... im still having troubles visualizing it though... turn the crank to the top of the stroke... take .3 off the bottom of the journal... it seems like since the bottom of the rod is now .3 higher the piston should be .3 higher. how would it be half? ... oh nevermind i get it now... measured from the center of the pin to where the rod cap meets the rod... my bad

thanks guys i have been writing everything down,if there is anymore info let me know before i go to the shop.
thanks again.

It all is dependant upon what rod you wish to use.
An aftermarket Chrysler 440 rod is 6.765" long and the small end is bushed to .990".
A aftermarket Pontiac rod is 6.625" long and the pin end is .980" and they are sold both press fit and bushed.
Aftermarket Chevy rods for a Ford are sold at 6.535", 6.635", 6.700", 6.800" and 7.100" with a bushed .990" pin end.