phongshader Justin Brown Ca (63 posts) Registered: 02/19/2010 04:03PM Main British Car: Locost Lotus 7 2.3 Duratec |
con rod wrist pin bore
I'm looking at some Nascar 6.125" con rods but the wrist pin bore is too small for the pistons I want to use. The pin bore is 0.787" but the pin dia is 0.866"...would boring out the rod pin bore to accommodate a 0.866" wrist pin weaken the rod too much, advisable? Floating pins, by the way.
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mgb260 Jim Nichols Sequim,WA (2482 posts) Registered: 02/29/2008 08:29PM Main British Car: 1973 MGB roadster 260 Ford V8 |
Re: con rod wrist pin bore
Depends on how big the top end of rod is. .048 bigger all around. EDIT: .0395
Edited 1 time(s). Last edit at 03/22/2024 05:39PM by mgb260. |
phongshader Justin Brown Ca (63 posts) Registered: 02/19/2010 04:03PM Main British Car: Locost Lotus 7 2.3 Duratec |
Re: con rod wrist pin bore
I don't have the rods so I don'y know the answer on how big the top end of rod is. ".048 bigger all around" means what? The pin diameter difference is .079 larger...
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mgb260 Jim Nichols Sequim,WA (2482 posts) Registered: 02/29/2008 08:29PM Main British Car: 1973 MGB roadster 260 Ford V8 |
Re: con rod wrist pin bore
Divide by 2 for each side. Should be .0395 each side or all around if centered.
I don't know where the .048 came from. Edited 2 time(s). Last edit at 03/22/2024 05:37PM by mgb260. |
Re: con rod wrist pin bore
Many engines using floating pins, steel on steel. Must lube the pin adequately. When you say weakening, meaning tension ?
To answer that, look at LS7 titanium rod. |
DiDueColpi Fred Key West coast - Canada (1384 posts) Registered: 05/14/2010 03:06AM Main British Car: I really thought that I'd be an action figure by now! |
Re: con rod wrist pin bore
Depends upon the rod.
Lots of the Carrillo's have a relief around the big end and probably wouldn't tolerate that much of an overbore. I would hunt down some Pankl's with the 0.827" pin bore and ream them out. They appear to have the beefiest small end. So a 0.039" overbore should be just fine. On the other hand, depending upon what you're building, the LS rod might be a better choice. They are strong, cheap and have the 2.100" big end bore that you probably need. The small end is 0.927" so a bushing is safe and easy. Live like you mean it Fred |