0.096" offset on stock 350 con rod

Bill, any thoughts on this??

I'm curious about using these Carrillo rods and with a stock type piston, a freind is looking to do this with these rods (pics and specs bellow). Using some pistons that would normally be about 9.5 the shorter carrillo rods would lower the comp distance to a make about 8.5:1 which would work good since he will be using turbos.

Based on this info the stock con rod has an offset, does anyone have any more details about this offset?

6.38700 Center to center length
2.00000 Crank pin Diameter
2.12500 Big End Diameter
0.94000 Pin Diameter
0.09600 Offset
0.83500 Max Width At Bore End
3.85000 Stroke
3.80000 Bore
10.1800 Deck Height
1.92500 1/2 Stroke
1.81000 Compression Height
10.1220 Total
(0.0580) (Down in Bore

 

Wow! Thanks Bill.

 

Bill, very informative. Which way is the piston offset on the con rod.
Marc

 

Piston pin offset I understand.

Connecting rod offset???????

 

That's got me confused too. Wouldn't the pin offset be machined into the piston itself? Since the rod is just a link between two points It's hard for me to see how it could have any offset other than sideways between the big and small ends going front to back in terms of the engine itself. Are Buick rods made with such a type of stagger?

Jim

 

Bill, after thinking about what you said about offset con rods I don't think the offset would have any affect on when the piston or con rod reaches TDC. The piston will be at TDC when the centre lines of the crank, main & piston are in alignment at the top of the stroke. Offsetting the wrist pin in the con rod or piston can not affect this. I think offset in a con rod would refer to a sideways offset??? Also Sean, where in the specs did you see that these rods had a .o96" offset & what were they originally for?
Marc

 

Looking at the stock rods from the side we can see the "offset" that is designed into the rod so that the rod bearings stay clear of the fillet on the side of the crankshaft.



The Fillet on the crank is shown here:

 

Looks good, Sean. Looks like that offset feature may help generate a type of 'hydraulic wedge' between the rod and the outer edge of the crank, aiding in lubrication there and helping it to stay clear of the side of the crank.


Gary