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Spun Rod Bearing #1561835 01/11/14 02:29 PM 01/11/14 02:29 PM
Joined: Dec 2004 Posts: 415 New Braunfels, TX 4 416challenger OP mopar
416challenger OP mopar 4 Joined: Dec 2004 Posts: 415 New Braunfels, TX	What would be the cause of a spun rod bearing? The motor is a 418 small block that has been together since the beginning of 2008. Probably has well over 1500 passes and 1000 miles on the street. The bearing were inspected and look good around January 2012 and they looked good. I run a 7 quart Milodon pan with full groove main bearing and a high volume oil pump. Last Saturday on my second pass the car felt slow and was slow to pull to 6500 rpm. I went through the traps and lifted and heard a bottom end noise. I pulled the motor apart Sunday and I had spun the #4 rod bearing and pushed it out towards the crank. When it lost the bearing it hammered the rod and bent the rod cap. All the main bearings looked fine. Why after all of this time did it spin a bearing?

Re: Spun Rod Bearing [Re: 416challenger] #1561836 01/11/14 04:03 PM 01/11/14 04:03 PM
Joined: Aug 2003 Posts: 43,223 Bend,OR USA C Cab_Burge I Win
Cab_Burge I Win C Joined: Aug 2003 Posts: 43,223 Bend,OR USA	Pull the rest f the rod bearings and look hard at them for debris and to see if they have lost the bearing crush, if they are still snug and don't fall out of the rod caps and rods If they fall out they have lost the bearing crush, probally from detonation or pinging Detonation, debris and inadequate(SP?, to little) clearances are the biggest reason for rod bearings spinning, your motor live quite awhile so I would rule out the clearances being the issue IHTHs Let us know what you find Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)

Re: Spun Rod Bearing [Re: Cab_Burge] #1561837 01/11/14 04:57 PM 01/11/14 04:57 PM
Joined: Nov 2003 Posts: 1,840 NW Indiana F fbs63 top fuel
fbs63 top fuel F Joined: Nov 2003 Posts: 1,840 NW Indiana	What rods? Lower quality rods will go out of round when torque cycled a few times.

Re: Spun Rod Bearing [Re: 416challenger] #1561838 01/11/14 05:53 PM 01/11/14 05:53 PM
Joined: Jan 2003 Posts: 5,486 SoCal Brian Hafliger master
Brian Hafliger master Joined: Jan 2003 Posts: 5,486 SoCal	Quote: What would be the cause of a spun rod bearing? The motor is a 418 small block that has been together since the beginning of 2008. Probably has well over 1500 passes and 1000 miles on the street. The bearing were inspected and look good around January 2012 and they looked good. I run a 7 quart Milodon pan with full groove main bearing and a high volume oil pump. Last Saturday on my second pass the car felt slow and was slow to pull to 6500 rpm. I went through the traps and lifted and heard a bottom end noise. I pulled the motor apart Sunday and I had spun the #4 rod bearing and pushed it out towards the crank. When it lost the bearing it hammered the rod and bent the rod cap. All the main bearings looked fine. Why after all of this time did it spin a bearing? Did you change anything, like tuning, fuel type, old fuel? Over reved? Same oil always used?

Re: Spun Rod Bearing [Re: 416challenger] #1561839 01/11/14 06:18 PM 01/11/14 06:18 PM
Joined: Jun 2003 Posts: 52,972 Romeo MI MR_P_BODY Master
MR_P_BODY Master Joined: Jun 2003 Posts: 52,972 Romeo MI	For ONLY one rod... I would guess it was the weakest point and stretched that cap

Re: Spun Rod Bearing [Re: 416challenger] #1561840 01/11/14 06:23 PM 01/11/14 06:23 PM
Joined: Jul 2005 Posts: 1,301 Penna 7 70satelliteguy pro stock
70satelliteguy pro stock 7 Joined: Jul 2005 Posts: 1,301 Penna	"Probably has well over 1500 passes and 1000 miles on the street" Man that is a lot of PASSES I would be thrilled if I could get that many passes out of any racing motor! Mike

Re: Spun Rod Bearing [Re: 70satelliteguy] #1561841 01/11/14 08:14 PM 01/11/14 08:14 PM
Joined: Dec 2004 Posts: 415 New Braunfels, TX 4 416challenger OP mopar
416challenger OP mopar 4 Joined: Dec 2004 Posts: 415 New Braunfels, TX	One additional rod bearing(#3) was about to spin. The bearing was loose in the rod when taken apart. All other rod bearings looked fine. The rods are K1. The tuning, fuel and timing all the same. It should not have been overreved, but I changed rear gear from 4.10 to 4.30 back in October. With the 4.10s I was shifting at 6500 and crossing the stripe around 6300. With the 4.30s I am crossing the stripe at about 6600. I have one rev limiter for the burn out box set at 6000 and the second set for 7000. I never hit the 7000 rev limiter. What oiling modification are typically done on the 340?

Re: Spun Rod Bearing [Re: 416challenger] #1561842 01/11/14 08:56 PM 01/11/14 08:56 PM
Joined: Mar 2008 Posts: 883 Affton MO Q qwkmopardan super stock
qwkmopardan super stock Q Joined: Mar 2008 Posts: 883 Affton MO	What is the endplay on the crank? And how does the #3 main bearing look? The #3 main feeds rods 4 and 5. If the endplay is getting wide, you could be starving bearings 4 and 5 because of bleeding oil from excessive endplay. Additionally, what main bearings were in your engine. The reason I ask is the clevite bearing part #ms963P for the 340, is full groove bearings except for #3 which only has the groove in the block side. If this is the case you were only oiling the #4 and #5 rods 1/2 of the time. I do not know why the ms963 bearings are that way unless Chrysler did it that way for some odd reason. If you use part #ms1344, which is for a 318, all positions 1-5 get the full grooved bearing, and as a bonus they are $25.00 cheaper. I have over 1800 passes on my 418/360 and shift at 7200 with a 8000 chip in the rev limiter, and hit it ocaisonally during the burnout. Nothing like the sound of an engine near 8000RPM in the burn-out box!

Re: Spun Rod Bearing [Re: 416challenger] #1561843 01/12/14 04:10 PM 01/12/14 04:10 PM
Joined: Jan 2003 Posts: 6,355 Cambridge Vt. mark_gates master
mark_gates master Joined: Jan 2003 Posts: 6,355 Cambridge Vt.	I think if I'd had it apart enough to inspect the bearings, I would've thrown in a new set, just for insurance. Even if it's just pulling the pan, it's still doable and cheap. 1500 runs is plenty; sounds like they pretty much are timed out. I'm glad you didn't throw the rod. 1.41/6.46/10.15/135.60 3650# http://www.soundclick.com/bands/default.cfm?bandID=938869

Re: Spun Rod Bearing [Re: mark_gates] #1561844 01/12/14 09:18 PM 01/12/14 09:18 PM
Joined: Dec 2006 Posts: 3,395 Pa Hot 340 master
Hot 340 master Joined: Dec 2006 Posts: 3,395 Pa	Quote: I think if I'd had it apart enough to inspect the bearings, I would've thrown in a new set, just for insurance. Even if it's just pulling the pan, it's still doable and cheap. 1500 runs is plenty; sounds like they pretty much are timed out. I'm glad you didn't throw the rod. with Mark.

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