Season over....tossed a rod...
08-18-2014 | 09:39 PM
#72
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From: Tennessee
Eddie
08-18-2014 | 09:55 PM
#74
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I don't understand it either. It's around $50-$60 on most sets of rods out there. To me, it's just cheap insurance. That's not to say that an 8740 bolt won't work in some apps. I'm just a huge fan of over building it, if you will. When you are building something that's 20K, or possibly a whole lot more, what's $50.
Eddie
Eddie
To expand on the technical side of this some more.... The jump from the 8740 (200K psi tensile) to ARP2000 (220K psi tensile) is only 10%, while L19 (260K tensile) is 30% more, but before people go claiming that the 8740 is "junk" they just need to compare it to a Grade 8 bolt at 150K tensile strength, 8740 is 33% stronger than a Grade 8 bolt! If we look at yield strengths the 8740 and ARP2000 are both right at 180K psi yield, or 50% more than a Grade 8 bolt.... and yeild is a much better figure to look at here.
At or below 6200 ish with a 4" stroke crank and a flat top, the 8740 bolt is fine. The 2000 is a better bolt, but not necessary in that application.
08-18-2014 | 11:00 PM
#75
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I can totally relate. had a fresh 548ci motor do the same 2 seasons ago. not a good year at all. Then dropped the topend onto a 454 short block and ran the dog out of it for the rest of the season. dropped a 489 back in this season to have it break 2 tiebars on the lifters. now hoping to get it back together for the lake cumberland poker run just in time for the last hooorahhhh on the water
08-19-2014 | 01:05 AM
#76
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True the 8740 isn't the best, but it's ten times the bolt that comes in any GM rod. I think Bob hit the nail on the head reagarding this issue. Say what you will about eagle and Scat, discuss 4340 variation and nitride depth until you are blue in the face... It's s 600 hp engine. Again, he doesn't need a Bryant crank and Oliver rods for the love of god! And to be honest I've beat the snot out of 8740 ARP's and if stretched correctly they last just fine. Are they a 2000 series, NO, but do you REALLY need that much bolt?! I agree the 50-$60 is a no brainer, ok however GM forged rods would be just fine in this application with upgraded rod bolts.
Last edited by Borgie; 08-19-2014 at 01:13 AM.
08-19-2014 | 05:03 AM
#77
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From: Olmsted Falls,Ohio Marblehead,Oh
interesting, I will still do the 2000's since it's coming apart...seems like a good idea, I assume you have the 8740's?
08-19-2014 | 05:04 AM
#78
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From: Olmsted Falls,Ohio Marblehead,Oh
I can totally relate. had a fresh 548ci motor do the same 2 seasons ago. not a good year at all. Then dropped the topend onto a 454 short block and ran the dog out of it for the rest of the season. dropped a 489 back in this season to have it break 2 tiebars on the lifters. now hoping to get it back together for the lake cumberland poker run just in time for the last hooorahhhh on the water
08-19-2014 | 05:20 AM
#79
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From: cleveland ohio
not sure oil pressure and temps were in spec, I watch gauges more then anything under a hard run like I was doing.... 70 spi and 200 degree temps... My machinist (Victory Engines) says he thinks rod bolt led to it... but yes oiling was addressed last summer they had on ly 55 psi wot and 260+ temps...until we fixed that
