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Discussion Starter · #1 ·
Hi.
I assembeled thie engine last winter. Had seen some bad reports of the bearings I installed on here. "But it couldn't be that bad?"

Got the engine running late this summer. However I soon figured something was wrong as oil pressure came down to 4 PSI....I hoped for the best and switched oil pressure sender, as I had som wrong readings earlier, but no. Top end was rather dry, and pressure sende as well.

It turned out, after several hours of testing that the lack of oil pressure was due to HEAVY leaking from mains/ rods. Did a "LIVE-SHOW" test priming the oil pump with a tray of oil hand held under the pickup. Fascinating experiment!

All the black coat is removed from the bearings. (NO shiny bits in oil or filter, thanks god...).

I have used coated Clevite bearings earlier- and may have seen the oil pressure make a dip (from 40's down to 25's at hot idle) after some weeks of use, but stayed OK for the lifetime of the build.

I'm after WHY this happened.... Are the coating very soft; too soft- and if the first start-up is a little bit too harse, the coating will be wiped out? Because- yes- there were misfires; too much timing due to wrong settings.

Ofcourse engine was primed before startup; oil getting to the rockers - everything OK. And BTW clearances checked and crank turning freely and light- handed. (Mains a little tight at 0.015, but aluminum block and should be OK?)

Here's a few pics of bearings and black grudge from oil-pan:
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Discussion Starter · #8 ·
Well, the digits may not be correct.....0015- 0020. That sound better?

Anyway- pump & everything else is bang on, so no. No other culprit found, YET.

There has been feedback on this type of bearing failing = dropping the coating (& oil pressure) first time out on the strip. That is why I THOUGHT it might be it.

Priming before start- up: oil all the way to the rockers.
After 3-4 startups, runnng for seconds at each go, oil to the top is lost; so is the pressure and the coating.
YES- I do understand the coating will be the first to go (and this is 1. aid...) if something else is amiss...

Belive me; I'm first in line understanding what went wrong.

I first thought of an e-ze fix, engine in car, but I'm pulling it out of there, inspect closer.
And while I'm at it do some changes that has been a PITA; Those fancy header studs makes it easy headers on/off- but makes changing plugs and getting the leads on/off taking for ever. Switching to 12p bolts.
THANKS!
 

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King XP's don't typically just lose the coating, they delaminate and "stack" material; completely wrecks the bearing and journal when it does. - We chased that battle unknowingly for several years, thinking it had to be builder(us) error. 3-4 passes and major failure, went everywhere from .0015-.0045 on the rods and .003-.0055 on the mains. Changed oil, pumps, pans, etc; it just seemed like it was too tight and/or starving for oil. Finally had a tech at a big name crank company go over everything with me and then describe to me exactly what the failed bearings looked like without seeing them himself; told me to swap bearing brand/type and the issue would go away, they had seen the issue with the XP's specifically in drag race motors.

We already had the motor back together so we elected to go make two test runs and bring it home to tear down. It wasn't yet hurt but bearings showed it was obviously headed there. Hand polished the crank, put it back together with Clevite H rod and ACL mains at the exact same clearances and 41 passes later when I nipped a piston and opened it up the bearings still looked perfect.





That aside, I agree with Chris U, the bearings pictured are not your loss of oil pressure. They aren't nearly that damaged.
 

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King XP's don't typically just lose the coating, they delaminate and "stack" material; completely wrecks the bearing and journal when it does. - We chased that battle unknowingly for several years, thinking it had to be builder(us) error. 3-4 passes and major failure, went everywhere from .0015-.0045 on the rods and .003-.0055 on the mains. Changed oil, pumps, pans, etc; it just seemed like it was too tight and/or starving for oil. Finally had a tech at a big name crank company go over everything with me and then describe to me exactly what the failed bearings looked like without seeing them himself; told me to swap bearing brand/type and the issue would go away, they had seen the issue with the XP's specifically in drag race motors.

We already had the motor back together so we elected to go make two test runs and bring it home to tear down. It wasn't yet hurt but bearings showed it was obviously headed there. Hand polished the crank, put it back together with Clevite H rod and ACL mains at the exact same clearances and 41 passes later when I nipped a piston and opened it up the bearings still looked perfect.





That aside, I agree with Chris U, the bearings pictured are not your loss of oil pressure. They aren't nearly that damaged.
That's weird. We have many 1500+whp engines with the xp bearings in them, and well over 100 laps with no problems......?
 

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That's weird. We have many 1500+whp engines with the xp bearings in them, and well over 100 laps with no problems......?

He noted it seemed specific to drag race engines, possibly per the flash load/heat created. The back to back difference for us was overly obvious.

Coloradoracer on here had a similar issue, put XP's in at a refresh instead of the previous HP's and had it wipe several bearings out in a few runs.


King themselves now lists the HP's recommended for drag racing, monster truck, and tractor pull engines and XP's for road-race/etc. They say the HP has a "harder babbit top layer to better resist extrusion & material migration". - HP – Alecular™ – King Racing (kingracebearings.com)
 

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He noted it seemed specific to drag race engines, possibly per the flash load/heat created. The back to back difference for us was overly obvious.

Coloradoracer on here had a similar issue, put XP's in at a refresh instead of the previous HP's and had it wipe several bearings out in a few runs.


King themselves now lists the HP's recommended for drag racing, monster truck, and tractor pull engines and XP's for road-race/etc. They say the HP has a "harder babbit top layer to better resist extrusion & material migration". - HP – Alecular™ – King Racing (kingracebearings.com)
The examples I referred to are all drag race, turbo combos (laps being passes). I do agree the HP is a harder bearing, and we use those exclusively in the 2-3k + hp builds. But have never seen a problem with the XP in the numerous 1500+whp LS engines we do.
 

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The examples I referred to are all drag race, turbo combos (laps being passes). I do agree the HP is a harder bearing, and we use those exclusively in the 2-3k + hp builds. But have never seen a problem with the XP in the numerous 1500+whp LS engines we do.

I gave away 5-6 full sets of bearings after our deal. - We had always used Clevites for years before but especially early 2000's it seemed it took 3-4 sets to establish tolerance in one motor; ie had some X's that were as tight as .001's...... :rolleyes:

I certainly learned a LOT more than I ever thought I needed to about the oiling system and we have found better reliability and power accordingly, but what an expensive way to get there. - We went as far as having two different machine shops check our tolerances and assembly methods and verify everything before going on the dyno or in the car to test. The back to back deal after 2 runs was mind boggling. Then we check back through our notes and realized the only other motor in the past ~8 seasons to go more than 5 runs also had Clevites, but due to other changes at the time we didn't catch the correlation.


Another very prominent OL632 car recently had a similar experience having a rod bearing spin 5 runs after a freshen up. They used bearings they had without giving a thought to brand, set tolerance and put it back in the car; it locked up as he pushed the clutch in on the burn out for the 5th run going into the semifinals. Bearings looked just as mine did when they tore it down, material stacked in sections and the coating still showing above where the material stacked.
 

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I gave away 5-6 full sets of bearings after our deal. - We had always used Clevites for years before but especially early 2000's it seemed it took 3-4 sets to establish tolerance in one motor; ie had some X's that were as tight as .001's...... :rolleyes:

I certainly learned a LOT more than I ever thought I needed to about the oiling system and we have found better reliability and power accordingly, but what an expensive way to get there. - We went as far as having two different machine shops check our tolerances and assembly methods and verify everything before going on the dyno or in the car to test. The back to back deal after 2 runs was mind boggling. Then we check back through our notes and realized the only other motor in the past ~8 seasons to go more than 5 runs also had Clevites, but due to other changes at the time we didn't catch the correlation.


Another very prominent OL632 car recently had a similar experience having a rod bearing spin 5 runs after a freshen up. They used bearings they had without giving a thought to brand, set tolerance and put it back in the car; it locked up as he pushed the clutch in on the burn out for the 5th run going into the semifinals. Bearings looked just as mine did when they tore it down, material stacked in sections and the coating still showing above where the material stacked.

Had the same tolerance issues with those bearing too.

Switched to ACL and the problem was solved.
 

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I made I think about 3-4 runs then at about 1000', car slowed like i pulled the chutes and hit the brakes at the same time. Before I could take my foot off the gas, BOOM! I was running King HP mains, but ran a set of the XP on the rods...killed 7&8 rod journal, broke a rod....Never had an issue before that, only had those bearings because I mis-ordered them.....figured they would be fine.....funny thing was, I had a solid 80lbs of oil pressure until there wasn't any oil left in the pan....
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Why can't some make 4 or 5 passes, and others have hundreds of runs on them?!?
 
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Either way, going back to the original post, the XP bearings didn't fail in the driveway for no reason!
 
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All I know is zero issues when using HP bearings before, nothing changed but rod bearings (even clearances were nearly identical), and boom.....back to hp bearings and zero issues since....

I don't have an answer, but I do know I won't run them again....
 

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I made I think about 3-4 runs then at about 1000', car slowed like i pulled the chutes and hit the brakes at the same time. Before I could take my foot off the gas, BOOM! I was running King HP mains, but ran a set of the XP on the rods...killed 7&8 rod journal, broke a rod....Never had an issue before that, only had those bearings because I mis-ordered them.....figured they would be fine.....funny thing was, I had a solid 80lbs of oil pressure until there wasn't any oil left in the pan.... View attachment 289823
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View attachment 289822
Damn that sucks that's an ugly looking mess!!
 
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