Piston guided engine Gen3 hemi

Stewart Way · 10-28-2018, 09:09 PM

I have a thread on another forum about a modified Gen3 Hemi block that has been modified to use an LS main bearing setup to get a 360 degree thrust bearing. Problem with it is it is 2.93 stroke and due to the block being modified for the LS thrust bearing which is narrower than a Gen3 forged crank in order to get a longer stroke it has to be a billet crank. No forgings with enough meat to be cut for the LS bearing.
Someone responded on the other forum asking if I had thought about a piston guided setup. Either I don't really understand that setup or it won't help. Can anylone see how it would help and maybe explain what I am missing. As I see it the piston guided setup just floats the small end of the rod with tight side clearance at the piston and at the crank it really doesn't matter since the rod only has side to side of 2-3 thou. Still need to have the end play limited by the thrust baring. Don't think you would limit end play by using rod big end or would you?
Any thoughts. No not a SS build, just looking for better brains than mine.

ss3011 · 10-28-2018, 10:59 PM

I think a piston guided rod has a lot of side clearance on the big end and relies on the piston to center up the rod on the crank . I don't think it has anything to do with crankshaft endplay . I don't really understand what the reason is for wanting all that side clearance at the big end , unless it helps more oil flow through the bearing . Possibly allows the designer to make a lighter piston .

Adger Smith · 10-29-2018, 05:06 AM

less rotating mass Big end of the rod is just a flywheel.

340Cuda · 10-29-2018, 11:10 AM

Quote:

Originally Posted by ss3011

I think a piston guided rod has a lot of side clearance on the big end and relies on the piston to center up the rod on the crank . I don't think it has anything to do with crankshaft endplay . I don't really understand what the reason is for wanting all that side clearance at the big end , unless it helps more oil flow through the bearing . Possibly allows the designer to make a lighter piston .

My understanding is that the piston guided rods had less friction. It was also told it was popular for NASCAR qualifying engines back when they could use them. I have had one motor with this setup and I agree it has nothing to do with crankshaft endplay.

Larry Hill · 10-29-2018, 02:13 PM

Would it make the piston rooster, read ( **** ) in the bore parallel to the mains?

Stewart Way · 10-29-2018, 09:09 PM

Haven't heard from the guy on Moparts to see how he thinks this will help. If I do I will let you guys know. Thanks for the responses.

10-28-2018, 09:09 PM	#1
Stewart Way Member Join Date: Aug 2003 Location: Atlanta Posts: 475 Likes: 15 Liked 70 Times in 21 Posts	Piston guided engine Gen3 hemi I have a thread on another forum about a modified Gen3 Hemi block that has been modified to use an LS main bearing setup to get a 360 degree thrust bearing. Problem with it is it is 2.93 stroke and due to the block being modified for the LS thrust bearing which is narrower than a Gen3 forged crank in order to get a longer stroke it has to be a billet crank. No forgings with enough meat to be cut for the LS bearing. Someone responded on the other forum asking if I had thought about a piston guided setup. Either I don't really understand that setup or it won't help. Can anylone see how it would help and maybe explain what I am missing. As I see it the piston guided setup just floats the small end of the rod with tight side clearance at the piston and at the crank it really doesn't matter since the rod only has side to side of 2-3 thou. Still need to have the end play limited by the thrust baring. Don't think you would limit end play by using rod big end or would you? Any thoughts. No not a SS build, just looking for better brains than mine. __________________ Stewart Way 2424 SS

10-28-2018, 10:59 PM	#2
ss3011 Senior Member Join Date: Feb 2002 Location: Southeast Michigan Posts: 885 Likes: 63 Liked 221 Times in 102 Posts	Re: Piston guided engine Gen3 hemi I think a piston guided rod has a lot of side clearance on the big end and relies on the piston to center up the rod on the crank . I don't think it has anything to do with crankshaft endplay . I don't really understand what the reason is for wanting all that side clearance at the big end , unless it helps more oil flow through the bearing . Possibly allows the designer to make a lighter piston .

10-29-2018, 05:06 AM	#3
Adger Smith VIP Member Join Date: Dec 2001 Location: Texarkana Ark/TX Posts: 2,348 Likes: 433 Liked 676 Times in 260 Posts	Re: Piston guided engine Gen3 hemi less rotating mass Big end of the rod is just a flywheel. __________________ Adger Smith (Former SS)

10-29-2018, 02:13 PM	#5
Larry Hill Live Reporter Join Date: Oct 2004 Location: Hickory, Ky Posts: 10,270 Likes: 1,631 Liked 9,422 Times in 1,951 Posts	Re: Piston guided engine Gen3 hemi Would it make the piston rooster, read ( ** ) in the bore parallel to the mains? __________________ IHM Used Parts https://ihmusedparts.com 888-821-1817** Last edited by Larry Hill; 10-29-2018 at 02:17 PM.

10-29-2018, 09:09 PM	#6
Stewart Way Member Join Date: Aug 2003 Location: Atlanta Posts: 475 Likes: 15 Liked 70 Times in 21 Posts	Re: Piston guided engine Gen3 hemi Haven't heard from the guy on Moparts to see how he thinks this will help. If I do I will let you guys know. Thanks for the responses. __________________ Stewart Way 2424 SS