Some background- built a 360 bracket motor some time ago, nothing too radical, but a fair amount of compression and too big a camshaft. I ran this combo and it made great power for many seasons. Usually launched it 4500, shifted at 6500 and everything was good. There was one time I overshifted the trans and it ran up to 7200, but it seemed unphased by that brief transgression. Oil pressure was always good, fired up easy, changed oil regularly, pretty good mill over all.

Over the last several years I've tired of bracket racing antics and decided to tame it down some for a hot street mill. It was running great, soI was planning on checking all the bearing clearances, making a cam change to something with less duration to make it a little more streetable, and pressing it back in to duty.

So I start pulling it down and things look good. However, as I pull rod caps, I find a couple that are a bit difficult to get the caps off. I think that is weird until the caps come off. The bearings are shot, they are into the copper. Thinking this really sucks, I tear things down further to remove the crank.

So looking at the damage, the bearings did not spin in the rods. The shells still had their tangs and they were in place in the rods correctly. The damage on the crank is minimal and I'd guess that turning the crank down -.010 will probably save it. All other rod bearings looked decent. The bearings were not dull any longer, but were smooth and shiny with no evidence of any debris being embedded in them. But rather than just clean things up, put it back together and go, I'd like to avoid this happening again. What looks odd is the damage to the crank is only on half the journal. So while I can plan and build an engine, I'm not so well versed in diagnosing what type of problem would have caused this issue and what to do avoid it happening in the future.

Here are pics of the crank damage. BTW, the two throws are seperated by the #3 main bearing. The two rods in question do show some blueing on them, so they got heated up. Can they be saved with some work or are they junk? Were the cranks throws ground out of round, were the rods resized incorrectly? Thoughts? Suggestions? Additional questions?

First picture is a side view showing how the damage is only on half the 2 damaged throws.


Turning it so one throw is up and the other down, you can see the bottom of one throw is clean, the top of the other crusty.


Similar view showing the other throw's damage.

I thought the same on oil starvation. Windage tray?

Had a 340 that looked a lot like yours. I blamed it on diluted oil. Had a float issue and flooding. I did not think it was bad. Replaced the float and ran it. Ran just fine but developed a slight noise. Tear down looked just like yours.

The interesting thing is the damage is to the back side of the throws & if it's oil starvation it's odd the two journals fed by the center main are fine but the outer journals fed by mains further out than we see are cooked... How do the throws further outboard look?

I would think oil starvation or dilution would have effected more than just half of these two throws.

Engine had a Melling high pressure pump, Moroso 8 qt pan, matching pick up and a Mopar windage tray. Oil level was always correct and pressure level was always good, even after several rounds in mid day summer heat it never dropped below 50 psi. All the other throws all look great. All the other rod bearings show wear, but all look consistent and no others were into the copper. All the main bearings are similar. I did not check any clearences on anything after finding the two bad bearings.

This engine was running strong right up to the last pass it made, which was a 12.2 @ 112. I never noticed and issue with oil pressure, don't recall any problems with excessive fuel wash. I don't recall any unsual noise the last weekend out, but it was never run with mufflers so any subtle change I might have missed.

Engine has lived on a steady diet of Kendall GT1 20/50, that was changed about every 10 runs. I bought cases and cases of it back in the early 90s before zinc levels became an issue. I'm down to my last 3 quarts now, so I've been thinking of switching to Brad Penn.

I forgot to check the feed source and can verify tonight, but aren't the two damaged ares feed by the #2 and #4 mains?

I have disassembled thousands of fuel and alcohol engines…. With that type of damage , the most common . we call it a blackened crankshaft…
Simple not quite enough oil lubrication and cooling - the area with the lowest oil pressure therefore the slowest oil speed and the highest temperature.
Usually the rod bearings that are the furthest away from new ( cool) oil coming from pump - #2 main feeds 2 rods and so does #4 ( # 1 and # 5 only feed 1 rod bearing)
Remember that the oil going threw the main oil gallery has to take some 90 degree turns ( fast moving oil doesn’t like doing that ) # 5 is forced to turn , because of the end of the gallery so it has lots of oil flow

Now the actual cause of it happening , on your last pass ( and it doubt that – it could have been an accumulation of many passes ), could have been slightly diluted oil or any reason to have just a little less ( or hotter ) oil..

A way to reduce the effect on those rods is to slow down the oil travelling in the oil gallery…. An old pro trick used on most race engines is called a rear oiler.
Simply T the fitting on the rear of your engine ( where the oil gauge is installed), drill and tap a hole after the filter in the oil pump and run a line to rear of motor, this reduces the speed of the oil traveling down the oil gallery and gives it the ability to turn down # 2,3,4 mains
Some of these pumps come with provisions for a rear oiler:
http://www.darkside.ca/hemi-oil-race.asp
Picture of large volume rear oiler on TFX block at bottom of page


Note: in the old days at a race track most of the match race blown cars….
With the guy laying on his back under the car, was simply hand sanding that very damage , to reduce any rough spots , pop in a new bearing , and making another pass…

Note: High volume pumps actually worsen the pressure discrepancy down the main oil gallery because the increase the speed of the oil , front and rear mains like it

Drilling out the feeds for the 2 and 4 mains, would be a good idea

Note: #3 has a thrust surface on the main which increases the amount of oil to those rods

Looks like the area that is damaged is when the rod is applying power. Detonation hammering the oil out and causing the damage?

and the reason it is only on the inside.... is that is the end of the push down during the power stroke.... hotest surface tempurature, and pressure .... as the pressure is reduced - exaust valve opens - it gets a pulse of new oil .
It wasn't ground oval , if that was your concern

Look again.. The damage is to the bottom of the throw when the load should be least... Combustion has already pushed the piston don the bore & the piston hasn't been pushed far enough up the bore to build allot of cylinder pressure....

when you look at PV diagrams for racing engines the pressure is often still going up at the end of stroke, especially at high rpm, and racing fuels that burn slower...( ther is also a delay as the oil is heated and the piston is traveling down)

this also suggests that detonation is not the main cause.
detonation blackens the outside of rod journals... assuming it is happening just before TDC

that is why I am saying it is not detionation

athoug a race engine probably is close to detionation often

we also dont know if he had full grove bearings or not...that would change when cooler oil was alowed to flow in

I want spell check also............

Sure would be a good time to be able to invite Dan @ Performance Only over for his opinion..... Maybe someone from Best Machine would like to comment....

Mains were full groove bearings.

The t fitting idea is neat, but I don't see how that would work on a small block with teh pump in the pan.

Sooo, it sounds like the crank is salvageable without too much work. How about the effected rods; replace them, rework them and what would be required?

sorry I was thinkin RB... on the small block we simply drilled out the passage.... and/or sleved the lifters for rollers

check the surface of the crank .... the cast ones often have cracks after heating like that

Drill out the passages meaning opening up the crank holes that are fed from the #2 and #4 mains or opening up the main feeds to those bearings in the block?

Drill/tap the pump for a 1/2" (NPT) pickup (bend a Hemi one to suit) & want 5/8"ID to the rotors/space the pickup 1/8" off the bottom of the pan w pickup parallel to the bottom of the inside surface of the pan. From the rotors downstream want 1/2"ID everywhere & drill the pump itself/rear cap/block all to 1/2"ID. Deburr the (2) right hand turns from the vertical passage out to the filter (1) is close & 1 needs a long shank rotary bit & on that one measure the depth of the tool so you dont get into the recess where the mini freeze plug that you'll install later sits that seperates the 2 horizontle passages. Drill/deburr the 2 horizontle passages out to 1/2" ID also. Drill the 5 angled pass side horizontle gallery to crank passages out to 5/16" (one or 2 may already b that dia or larger). Go SLOW w that use constant spray lube as if a bit breaks off you're in trouble (use plenty of lube). Drill/tap the crank to cam vertical passages & install setscrews & drill a small hole in each one w a 1/16" bit (that's all the oil the cam needs). Install the #2 and #4 cam bearings so the rocker arm oiling hole is blocked. Feed the heads either by drilling horizontally into the rear of the head in the threaded boss then down from the rear pedestal at an angle (.080") & feed the heads externally from T'ing off of the sending unit PSI or in the valley tapping into the main horizontle gallery over to halfway up the angle passage cast into the block on each side. Run a 5/16" ID line from the sending unit hole in thru the back china wall to the front of the pass horizontle gallery and I would block the front main from being fed from the pass hor gallery and feed that main and the dr side hor gallery w a 3/16" ID crossover right in the middle of the oil galley several inches from the pass to the dr gallery straight across transverse. Hi vol pump/hi flow filter system(system 1 or oberg). clearances main .0025 rods .0023 EDIT baffles in the pan

I'm converting from the Moroso deep sump drag pan to the new Milodon road race pan. The Milodon unit has a very nice sump with a diamond shaped containment area and 4 different trap doors. I've matched that with their pick up and windage tray. Interstingly enough, the Milodon tray is shorter in overall length than the mopar unit, but has more louvers around the diameter of the pan. You also have to adjust the height relative to the crank, unlike the mopar unit that sits on the pan rails.