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#2273488 - 03/21/17 01:26 AM Heavy Piston-Light Rod.... What have I done?
EV2Bird Offline
On Vacation

Registered: 06/23/14
Posts: 1739
Loc: Kansas Roads Between 0 and 140...
Simple fun iron headed bracket 360 build with parts on hand.

Its an LA but the bobweight came out just under oem magnum specs.

But im like 127 grams lighter on the rotating weight spec. 440g vs 567g (567 is la and mag specs).

What if anything will this do, good or bad?

Thanks!


Edited by EV2Bird (03/21/17 01:59 AM)

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#2273664 - 03/21/17 11:54 AM Re: Heavy Piston-Light Rod.... What have I done? [Re: EV2Bird]
JohnRR Offline
I Win

Registered: 01/20/03
Posts: 73344
Loc: U.S.S.A.
huh ?
_________________________
running up my post count some more .

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#2273694 - 03/21/17 12:45 PM Re: Heavy Piston-Light Rod.... What have I done? [Re: JohnRR]
dogdays Offline
I Live Here

Registered: 01/20/03
Posts: 15199
IF the bobweight is the same it'll require the same counterweight and the engine will respond the same.

By putting more mass at the end of the connecting rod you have increases the forces the piston and top part of the rod will be exerting on the rod bolts at TDC of the exhaust stroke. I hope your new rods have 7/16" rod bolts instead of the stock 3/8" size. Then all will be well. Even if you only have 3/8" rod bolts if you are using a 3.31" crank they'll be plenty strong. And it's not really strong I'm worried about, it's elastic deformation.

What I would worry about is the 4" stroke crank with a lightweight 3/8" bolt rod and a heavy piston. Then I'd say the larger 7/16" rod bolts would be just right.

Chrysler designers sure liked making things beefy. A 645 LA rod is nearly as heavy as many big block rods. And the NASCAR Hemi rods with their 1/2" rod bolts were more suitable as a murder weapon than as a part of a racing machine.

R.

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#2273784 - 03/21/17 03:24 PM Re: Heavy Piston-Light Rod.... What have I done? [Re: EV2Bird]
EV2Bird Offline
On Vacation

Registered: 06/23/14
Posts: 1739
Loc: Kansas Roads Between 0 and 140...
Im using a 12.5 domed piston and the scat I beam, low rpm 360, like no more then 6200.

VS stock rods and adding weight to the crank I used the scat I beams.

Its an old 360 la block, so at just over 1902 bobweight I moved things around a decent bit vs oem LA and Mag 360 specs.

So it seems im 100 grams lighter overall then a 360 mag.


Going off this page balance figures Im just wondering if it will act any different.

It seems probably not, maybe like the steel vs lightweight rim test.

http://www.dodgecharger.com/forum/index.php?topic=10449.0;wap2

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