TheBadGMC

Hello all I have been lurking for a long time and I appreciate all the answers that this site has provided for me. But I can't find an answer to my question with the search any help will be greatly appreciated.

After 2000 miles on the rebuild my 6.0 started knocking. The rebuild was very basic milled .03 317 Heads, Vinci Trucker low lift Cam, and flat top pistons. Nelson tuned.
I went ahead and replaced the rod bolts with ARP and had the rods resized +.002. I used the Clevite cb1776a rod bearings
The oil pressure was 40 psi at idle hot and climbed to 75 at WOT I never saw it drop below 40 psi.
While first driving the truck I noticed a tick that could only be heard in the cab when you let off of the throttle. I really thought it was an exhaust leak. Then after 2000 miles the tick turned to a knock. I pulled over and glitter on the dipstick.

I pulled it apart this weekend and discovered all eight rod bearings have
damage on the rod side only. I double checked the clearance with two good bearing halves using plasti-gage and it is .0024 at 90 degrees to the parting line.

I removed two rods and assembled them in a vise with out bearings and using a bore gauge they were round within .0002 (I know this isn't the best way to check but it is all I have)

With the bearings installed in the rod and with a bore gage it is good at 90 but it is +.0024 larger near the parting line.

All of the rod bearings have the same damage pattern and my oil pressure never dropped below 40 psi.

The main bearings survived without any damage.

Does anyone have any suggestions to why this happened while still having good oil pressure? Did the out of roundness of the installed bearings cause it? What am I missing?

I am going to have my Crank ground and order new Rods and bearings. I just don't want this to happen again.

PS
The oil pump is a melling high volume. 10w-40 dino oil
The Rev limiter is set at 5400 and I never spun it over 5000.

Thanks for reading

baronsmith98

iTrader: (2)

This may sound stupid and I apologize if I offend you but did you torque your rod bolts?

97FormulaWS-6

iTrader: (1)

And what did you torque them to?

RockinWs6

Ant signs of detonation on the tops of the pistons?

TheBadGMC

I used a bolt stretch gage to torque the rod bolts between .0055 and .006 per the instructions.

No offense taken I know I screwed something up just not sure what

No visible signs of detonation on the pistons

Thanks for the replies

baronsmith98

iTrader: (2)

Do you have a picture of the bearings?

RockinWs6

Yeah pictures would help but there are 2 big rod bearing killers.....low oil pressure and DETONATION. Detonation wears the ROD SIDE OF THE BEARINGS.............

Were the knock sensors tuned out or sensitivity changed?

Old Geezer

iTrader: (3)

" but it is +.0024 larger near the parting line."
Should be larger at the parting line. This prevents the edges of the shells from acting as an oil scraper on the journal, when the rods deform under load.

TheBadGMC

Ok I didn't expect it to be so much.

I am out of town now and will get some pictures when I return home.

I will contact the tuner and ask about the knock sensors I didn't request it but I don't know I he did.

Thanks

Smokin92z4

iTrader: (1)

Strange