Replacement Rods - Upgrade?

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VTICH

VTICH

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I've got my SB 415 torn down as the # 3 rod journal was bad. Crank is now ground and back in the block and I'm thinking I should replace the connecting rods with new ones as they appear to have already been out another time for a crankshaft replacement as, according to the original build sheet, the crank was supposed to be a Mopar Performance 4'' cast unit. Previous owner must have replaced with an Eagle 4'' 4340 for some reason. I assume the same issue as I'm having now and I'm thinking maybe a rod is bad causing the issue? I only have tools to check bore roundness which is fine, but they could be bent?

Rods in it now are Eagle "I" Beams which I read are 605 grams. The simple solution is to replace in kind with same rods but what about the Scat "I" Beams that are 595 grams in weight? Rebalance required you think? If so I'll stick with what is in it now, just though the Scat rods may be a bit of an upgrade.

I don't have the build sheet in front of me at the moment but the BOB weight was around 1730 or 1780 I believe.

Thanks for any suggestions you have.

Paul.
 
I would have it fully rebalanced. Have you done the block oiling mods?
 
What kind of power are you making anything over 500 h.p. stay away from the Eagle i-beams..ask me how i know KABOOM!!!
 
jbc426 said:
I would have it fully rebalanced. Have you done the block oiling mods?
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No oiling mods that I'm aware of. Stock 360 Magnum based block with RHS / Indy heads. Been doing lots of reading up on the subject though. Thanks.


stroked340 said:
What kind of power are you making anything over 500 h.p. stay away from the Eagle i-beams..ask me how i know KABOOM!!!
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Well, it was originally an Indy Cylinder Heads 415 Crate motor rated at 520 h.p. Find that a bit hard to believe with an camshaft intake duration of 236 degrees. I'm a bit worried about these rods too as mentioned, I think the crankshaft has already been replaced before and I don't know what the cause was (bought from an estate type sale, owner deceased). Eagles site says up to 500 h.p., Scat claims 650 h.p. on their rods. Just something to help you sleep better at night?

Thanks for you input.

Paul.
 
I picked up a set of used Eagle H-beams for my blown 340. I have no complaints. I had my machine work and balancing done at Rinaldi's in Maine. They were fast, good work and a good price as well. Much better than anywhere in New Brunswick.

Jack
 
Thanks Jack. I've got the crank machined and block cleaned from Central Machine in Fredericton, so far. I'm just around the corner from you, in Hampton.
 
Eagle "H" beam from our old W5 mill VS Molnar "H" beam in our W8 mill.... There are lighter, better alternatives....

 
A body said:
Eagle "H" beam from our old W5 mill VS Molnar "H" beam in our W8 mill.... There are lighter, better alternatives....

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Nice, I've looked at those Molnar units and read up on his history. I'll likely just throw a new set of Eagle I Beams in to save re-balancing. Not sure if I'm attached to this unit just yet. Was supposed to be a quick flip car as I'm looking to do something closer to a full resto type buildup. I may just throw the 340 back into also after an quick (LOL!) inspection / freshening up.

Thanks, Paul.
 
eagle I beams are chinese junk, no good for any high rpm. if the rod is replaced with others within 10% of weight, rebalance is not needed, I have done it, with solid engine mounts, hughes engines says so. where are scat made
 
Marcohotrod said:
eagle I beams are chinese junk, no good for any high rpm. if the rod is replaced with others within 10% of weight, rebalance is not needed, I have done it, with solid engine mounts, hughes engines says so. where are scat made
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Not really there good if your NOT making power over 500 h.p. have a set in my 400 h.p. 360..
over 500 h.p. not so good..
 
Marcohotrod said:
eagle I beams are chinese junk, no good for any high rpm. if the rod is replaced with others within 10% of weight, rebalance is not needed, I have done it, with solid engine mounts, hughes engines says so. where are scat made
Click to expand...

If this is true then I can go down (or up) in weight a fair amount. The Scats are a possibility, less than 2% change. Using 10% I could go up as high as 665 gram weight, that seems allot!
 
actually if you look at the Eagle rod in my picture you'll see damage on it..... it was one of the survivors when #3 kicked out the side of our W5 mill. Not faulting the rod..... coincidentally that cylinder was also the one we had a history of water intrusion into from the heads.
 
Marcohotrod said:
eagle I beams are chinese junk, no good for any high rpm. if the rod is replaced with others within 10% of weight, rebalance is not needed, I have done it, with solid engine mounts, hughes engines says so. where are scat made
Click to expand...

I'm not sure if I'm trying to convince myself that not sending out to re-balance is OK, but attached is a link about engine balancing and discuss option to over or under balance and by what percentage engine builders use. My thoughts are that changing to the better Scat I Beam road and dropping 10 grams / rod would leave me over-balanced 1.4%? Using 605 gram weight rod compared to 595 grams for the Scat.

http://www.enginebuildermag.com/201...uilding-tips-to-reduce-nvh-and-increase-life/
 
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