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Well pistons will be custom from Diamond and it will have the stock 2.375 rod end.

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Well pistons will be custom from Diamond and it will have the stock 2.375 rod end.

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What are you trying to say The 426 Hemi can have several different wrist pin sizes stock, SS Race Hemi, NASCAR Hemi and Street Hemi but all of them use the same size crankshaft rod journal sizes

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Well pistons will be custom from Diamond and it will have the stock 2.375 rod end.

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What are you trying to say The 426 Hemi can have several different wrist pin sizes stock, SS Race Hemi, NASCAR Hemi and Street Hemi but all of them use the same size crankshaft rod journal sizes

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Dude where did I loose you Im talking rod ratio. Im having "custom" pistons made so not sure Y wrist pin size matters? The crank that I'm looking at "recommends" a 7.10 rod for the 4.25 stroke. So my ? is, is the 6.86 rod length a doable rod ratio. I have the rods and trying to make use of them.

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Well pistons will be custom from Diamond and it will have the stock 2.375 rod end.

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What are you trying to say The 426 Hemi can have several different wrist pin sizes stock, SS Race Hemi, NASCAR Hemi and Street Hemi but all of them use the same size crankshaft rod journal sizes

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Dude where did I loose you Im talking rod ratio. Im having "custom" pistons made so not sure Y wrist pin size matters? The crank that I'm looking at "recommends" a 7.10 rod for the 4.25 stroke. So my ? is, is the 6.86 rod length a doable rod ratio. I have the rods and trying to make use of them.

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How does it have anything to do with it being a doable rod ratio ???

I just looked at Diamonds catalog online , they don't list a 4.25 stroke piston , but they do list a piston for a 4.150 stroke with a 6.86 rod, unless you are looking for something odd you can just have them make you the 4.150 piston of your choice and move the pin for a small upcharge.

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The man has already said "TWICE" that he's getting custom pistons, how hard is that to comprehend. In answer to his original question, yes, it is a doable rod/stroke ratio, 1.614. The 7.1 rod will be slightly better at 1.67, but that's not enough to justify buying a set of rods when he already has some he wants to use.

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I saw it TWICE , have you priced out a CUSTOM Diamond piston? they aren't cheap ... BTDT ... that's why I suggested that he could have them modify a shelf piston and save some money.

He has it set in his mind that he wants to use the rods he has , I get that and nothing is probably going to change his mind so the ROD RATIO is basically a moot point.

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The man has already said "TWICE" that he's getting custom pistons, how hard is that to comprehend. In answer to his original question, yes, it is a doable rod/stroke ratio, 1.614. The 7.1 rod will be slightly better at 1.67, but that's not enough to justify buying a set of rods when he already has some he wants to use.

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Thank you, That was the info I was looking for.

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The man has already said "TWICE" that he's getting custom pistons, how hard is that to comprehend. In answer to his original question, yes, it is a doable rod/stroke ratio, 1.614. The 7.1 rod will be slightly better at 1.67, but that's not enough to justify buying a set of rods when he already has some he wants to use.

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Thank you, That was the info I was looking for.

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But that wasn't what you asked originally ???

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Im thinking about putting my street Hemi together.My question is, can I use a 6.86 rod with a 4.25 stroke crank. I have the rods already so I would like to use them. Most of the cranks that I looked at say to use a 7.10 rod. Thanks, Jim

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But if you want to drop over 1k on a set of custom pistons go for it.

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The best thing might be to move the Hemi rods along if you are planning to use the internal oil pickup with a 4.25 stroke and Mopar rod journal. You will struggle to achieve conrod to pickup clearance.Go with the 4.25 stroke and BBC rod journals and 7.100 rods. These are the Diamond pistons I had made for this purpose:

#61997
Bore = 4.280
Comp Height = 1.500
Effective Volume = +75.29
Pin = .990
Rod = 7.100
Stroke = 4.250

These pistons will give you aprox 10.5 to 1 with 170cc head and a .040 gasket.

Also you may find it hard to find anyone who offers a 4.25 stroke and Chrysler rod journals!

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I hear you,That would be the best bet.The only thing getting in the way of doing that is a new set of 6.86 Manley pro-series I beam rods that I would like to use. Im waiting on a phone call from RPM Engines to see if Scat has the 4.25 stroke with the mopar rod journal.On there web page it says they do.If this does not work out, I think the easy way around this is to use the 4.15 stroke crank. Right now I'm just looking at all my options.Oh, 1 more thing I am using the Milodon single line system. Thanks

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You can use any length rod that will fit. The better question is if there is an off the shelf piston that will work. Also is you're crank BB Chrysler rod journal dia.(2.375) or BB Chevy (2.200).

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You can use any length rod that will fit. The better question is if there is an off the shelf piston that will work. Also is you're crank BB Chrysler rod journal dia.(2.375) or BB Chevy (2.200).

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My 426 racng engine has 3.763" stroke and 4.35" bore with Diamond custom pistons. The rods are from Oliver with the standard HEMI 2.375 rod journal size.

Would there be a performance gain to go to 2.200 Chevy rod journal size ?

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Well pistons will be custom from Diamond and it will have the stock 2.375 rod end.

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I haven't seen a 4.250 crank with a mopar rod pin , not that they aren't out there, but with that length rod it's going to be a 1.74isch CH piston, definitely a little shorter than stock. A 7.100 rod might be a better choice and Diamond may have a shelf piston for that combo ?

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got one in my garage right now?? Ok it's 2.365? :-)


seems new cranks are leaning 2.2 journal size does make them easier to clearance the rods in the block so you may end up with new rods and pistons at that point check out stoker kits!