Odd main bearing marks

[blykins]

With only 400-450 horsepower, I too would look for another cause other than power.  Detonation would possibly show up on rod bearings and piston crowns.   Cap fitment would be a good spot to look. 

[machoneman]

My thoughts as well Brent. Perhaps the main studs weren't torqued correctly. Check your wrench or borrow another to test both on say engine stand bolts or another bolt by comparison. At that level of hp, something else is amiss, which is why I asked about piston, ring, ring land condition.

[gdaddy01]

are the ends of the bearings curling in at the end , were the main caps mating surface machined after the align hone ?  bearings not having any crush with the caps tightened down .

[Jim Comet]

The rod bearings look good to me. Here is a pic of a rod bearing and piston top. I don't think it was detonation. Also, I pulled the studs and installed a main cap. I had to tap it into place with my fist and wiggle it out as it seemed to fit fairly snug. Jim

[blykins]

Did the rod bearings fall out of the rods or do they still fit snugly?

Does that area that looks pitted at the center of the piston feel rough? 

[Jim Comet]

Bearings were snug. They stayed in the cap and rods as I removed them from the block. No pitting on the piston, it is actually carbon, I just went out and scotch brighted it with a little brake clean and there is no pitting. cleaned up smooth. I am going to have a machinist look at and fix up the register area. But as of right now they only thing that may be suspect is my torque wrench. Now that I think of it the only main bearing without the odd wear pattern is the center thrust. I will look tonight and see if that one has metal transfer also. Jim

[Barry_R]

Side view of pistons and rings with close up please.

Is the second ring free to spin in the groove or does it feel snug?

[Jim Comet]

I can get photos tonight. The second rings are Total seal 2 piece gapless. They do move and rotate freely. Jim

[mike7570]

But as of right now they only thing that may be suspect is my torque wrench. Now that I think of it the only main bearing without the odd wear pattern is the center thrust. I will look tonight and see if that one has metal transfer also. Jim

What did you torque them too?
I think ARP recommends 110 on FE mains

[Jim Comet]

I wish I could remember 20 years ago. I am sure I would have torqued them to what the instructions that came in the box with them said. At this point I think I need to have the registers checked and also my torque wrench calibration. I live in the Twin Cities, are there any places a guy can take his torque wrench to to get it checked. It is a early 90's era Craftsman clicker. My dad taught me to always release the tension on it when not in use to help maintain accuracy. Jim

[machoneman]

Jim: look here.....

https://www.thomasnet.com/minnesota/calibration-services-10021202-1.html

[jayb]

Here's how I do it:

http://fepower.net/simplemachinesforum/index.php?topic=352.msg2846#msg2846

[Joe-JDC]

I just tore down an engine with similar but lesser witness marks, and found that the flywheel bolts had been hitting the rear main seal area and actually gouged a groove in a circle on a different Ford engine family.  The main thrust bearing was worn on the sides, but the rod bearings looked good.  Just an extra item to check on assembly that the flywheel bolts didn't hit the block.  Joe-JDC

[TorinoBP88]

I would recommend a line hone on the main.

[Heo]

But as of right now they only thing that may be suspect is my torque wrench. Now that I think of it the only main bearing without the odd wear pattern is the center thrust. I will look tonight and see if that one has metal transfer also. Jim

What did you torque them too?
I think ARP recommends 110 on FE mains

Those recomendations was not with my studs. But i milled down the 5th cap and spotfaced all caps when i changed from bolts
to stud and nut. The bolt have the Bufo ring under the head and after the engine have been apart a few times the ring have often
dug in to the caps and the flanged nut dont get the correct support. So after a while when things have moved around the torque loosens upp. The first set of studs was bottoming out i the holes so i put a steel ball in there to pre load the treads even The other set bottomed out in top of the threads so there was not room for a ball big enough to meet the stud