Hemi vs 440 Connecting rods. Aftermarket

[Nxcoupe]

I am looking to buy some I
or H beam aftermarket rods for my 66 hemi, and it seems the only difference between the two rods is the pin diameter, does that sound right? Both are same length, same big end diameter and width, but the Hemi pin is .040 larger than the 440 from what I can tell which doesn't matter since I'll be ordering the pistons custom anyway.

What say you masters of all things Mopar tech?

 

[forphorty]

Length of stock rods is different. 6.76 for 440 and 6.86 for Hemi.

 

[Nxcoupe]

Length of stock rods is different. 6.76 for 440 and 6.86 for Hemi.

Ah, so I could just use 440 pin height in the custom piston and be fine?

 

[33 IMP]

Yes, you could.
Considering that you are doing custom pistons, I would have the rods bushed for a big block chevy pin. Plenty strong enough, and WAY lighter than a stock hemi pin (which was way heavier than they needed to be.)

 

[Rebelrouser]

Yes, you could.
Considering that you are doing custom pistons, I would have the rods bushed for a big block chevy pin. Plenty strong enough, and WAY lighter than a stock hemi pin (which was way heavier than they needed to be.)

Most of the 440 stroker kits use a big block chevy rod now and the rod journals are reduced in size to a big block chevy as well. Lot easier to make clearance for a big stroke.

 

[33 IMP]

Ye

Most of the 440 stroker kits use a big block chevy rod now and the rod journals are reduced in size to a big block chevy as well. Lot easier to make clearance for a big stroke.

Yep, would have suggested that, but I think he wants to use his Hemi crank.my 522 uses 7.1 Chevy rods, and the crank is cut for them. The 7.1" h beams and rat pins are a couple hundred grams lighter than stock hemi rods and pins. Won't mention how much lighter the pistons are......

 

[Nxcoupe]

Most of the 440 stroker kits use a big block chevy rod now and the rod journals are reduced in size to a big block chevy as well. Lot easier to make clearance for a big stroke.

Ye
Yep, would have suggested that, but I think he wants to use his Hemi crank.my 522 uses 7.1 Chevy rods, and the crank is cut for them. The 7.1" h beams and rat pins are a couple hundred grams lighter than stock hemi rods and pins. Won't mention how much lighter the pistons are......

But are the BB chevy rods the same big end width? Or does it require a special crankshaft?

 

[33 IMP]

The stroker cranks (chinese 4340) are cut for big block chevy rods journal size (smaller than 440/hemi), and rod width.
Pretty sure that if you cut down a hemi crank for bbc rods, you get more side clearance than recommended, but haven't heard anybody say that's a huge problem.
A few (maybe many) years ago Manley made specific rods for mopar cranks with BBC pin diameter, but Mopar thickness, but they were disco'ed years ago.

 

[Nxcoupe]

Looks like 440 rods it is!

 

[33 IMP]

NX, if I were you, and wanted to keep my hemi crank, just as it is (and I would), I would get some H-beam 440 rods from Molnar, with Chevy pins, and get custom pistons to suit. You were gonna do custom pistons anyway, right?

 

[Nxcoupe]

NX, if I were you, and wanted to keep my hemi crank, just as it is (and I would), I would get some H-beam 440 rods from Molnar, with Chevy pins, and get custom pistons to suit. You were gonna do custom pistons anyway, right?

Yep, that's the plan. Or just use a 440 pin. Either is fine as engine won't see over 6500.