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FE Power Forums => FE Technical Forum => Topic started by: hbstang on August 29, 2025, 01:50:53 PM

Title: crankshaft stroke and rod journal size
Post by: hbstang on August 29, 2025, 01:50:53 PM

i have a crank that has the chrysler 2.375 rod journal size,and stroke is  4.375.due to the location of the rod lightning hole theres no way it can be turned to 2.200 dia. and maintain that stroke.maybe it could be offset ground to 4.500 or so.is that a stroke that can be used in a 427 sohc engine with no cam lobes?

Title: Re: crankshaft stroke and rod journal size
Post by: fekbmax on August 29, 2025, 02:17:26 PM

You would probably be getting into rod to camshaft clearance issues.  This even happens some with a 4.375 stroke.  Normally you can clearance with the 4.375 but the 4.50 may be to tight. Also take into consideration as to what that grind would do to the  location of the oil passages. 

Title: Re: crankshaft stroke and rod journal size
Post by: Stangman on August 29, 2025, 10:38:23 PM

I’m not sure but I think Jay has a 4.50 crank in his SOHC.

Title: Re: crankshaft stroke and rod journal size
Post by: jayb on August 29, 2025, 11:13:39 PM

I have run a 4.6" stroke in the SOHC and currently have a 4.75" stroke for my race SOHC motor.  You can use a very long stroke with the SOHC.

Title: Re: crankshaft stroke and rod journal size
Post by: My427stang on August 30, 2025, 06:02:36 AM

I am no SOHC guy, but I would be less worried about stroke and more worried about that much cut walking the oil feeds toward the outside edge

Although wouldn't be taking the full amount off the entire journal, it's quite a cut in some areas. I don't have a crank in front of me to see where they clock, my guess it would be about 1/2 the cut at the oil holes, which should be OK, but depends where they drilled them

Title: Re: crankshaft stroke and rod journal size
Post by: fekbmax on August 30, 2025, 06:20:33 AM

Apparently I didn't read the last line where he mentioned it being for a SHOC. My bad..

Title: Re: crankshaft stroke and rod journal size
Post by: 475fetoploader on August 30, 2025, 10:24:13 AM

Could a Chrysler rod be used? You’re probably special ordering pistons regardless, just use the Chrysler pin size.
It seems to me Chrysler Rods are right in the ballpark for length.  Pin was maybe 1.094 or something diameter.  I understand not wanting the bearing speed associated with the Chrysler, however I did see one go pretty good once.

Title: Re: crankshaft stroke and rod journal size
Post by: hbstang on August 30, 2025, 02:32:32 PM

thanks for all the replies.because the rod journal is not parrelell with lightning hole,i dont think offset grind is possible either.will look at it closer.but i do see that molnar has a 6.76 rod for this 2.375 dia rod journal.i think they are good rods and will be fine.

Title: Re: crankshaft stroke and rod journal size
Post by: hbstang on September 12, 2025, 04:20:45 PM

yes,molnar has a h-beam rod that would work fine.i just wonder about the rod journal and rpm,maybe 7,000 max would be ok i guess.