been driving my duster for over 2 years now and running great.couple weeks ago went to start it and spun the main bearing,it has full oil pressure and still runs.trying to figure out what happened.I usually only drive it on the street but recently drove it about 5 miles on the freeway a week later this happened.the rpm"s on the freewav was around 3500.I recently heard something about not holding high rpm"s for lengths of time but not sure about this because 170 motor had higher compresson and used for racing.
My car has 9.7-10 comp. .510 cam,head port and polish,hyperpac,500 edelbrock carb, 4.10 gears.any input would be great . never know, may be just one of those things.thanks

Your engine should be fine at high RPM, all day so long as the cooling system can keep up. It sounds similar to what happened on my Valiant last year, where it was running great, and tried to spin the #1 rod bearing. I found on mine that a chunk of casting sand had broken loose, and found its way into the #1 rod oil hole. It went round and round and took some of the bearing material with it, then got lodged in the cylinder squirt hole.

It may just be one of those things... however;

You would not be the only Robert here having issues similar to yours. I think us Roberts have angered the slant six gods recently.

For example, My '65 Dart randomly chewed the oil pump gear, which chewed the cam gear, and so I had to replace the cam and the pump.

Then, I drove it all week, no issues. The night before last I was walking out of mal-wart and started her up. the oil light went out, then came back on. I shut her off, let it sit, started her back up, and the same thing happened.

I performed an oil and filter change in the parking lot hoping that might cure it, no dice. Fast forward to today, the car sat for a little over a day. I started her up to move her into the driveway for tear-down, and magically, the oil light shuts off like it should, doesn't come on anymore once running, and she runs just like she did before.

*shrug*

DusterIdiot's oil pump decided to clock in late for its first day of duty, and when he started his brand new build, it ran for 2.5 minutes, then fragged.

Now, you have a spun bearing.

Is there a pattern here?

Yes. Our names are all "Robert"

WHY?!?!?!?!?!?!?!?!?

One of those things....

Where do you live?

~RDE~

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Part of Tyrde-Browne Racing

I guess the name Robert and slant six don't get along anymore.usually this is how well I get along with computers.you are talking to the guy who walked in to the bank swiped my debit card and crashed there computer. Iam in so.california.

Sorry to hear that, Robert. How do you know it spun a bearing if the oil pressure didn't drop? Hearing a knock? Could such a knock be something else like a split damper keyway??

Best,

Lou

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Home of Slant6-powered fun machines since 1988

WWhat did the bearing look like? AFter it spun sometimes its hard to tell what the real problem was but color and condition can help figure it out.


What about the rest of the bearings color and condition?


One thing about running low gears and turning high RPM is, the oil level gets to be very critical. Let it get just one quart low on oil, then start making runs through all three gears (or four if stick) and when you get in high gear pulling top RPM you can starve a bearing of oil. Sometimes its hard to see this on the oil pressure guage, sometimes you might just see it pull back a little, or even spike real quick.


Of course when running high compression if the engine is allowed to spark knock this can cause bearing problems.


You have to tear down, look at the engine as a whole, then look at each cylinder, piston, cylinder walls, rod bearings and then each main and get a big picture look at what might of been going on with your engine.


Look at the oiling path of the oil system. Which bearing, or bearings get oil last? Which bearings gave problems? Whats the wear pattern on the rest of the mains?

There is many ways to help prove what really happened. Getting detailed info out of your engine will help find the answers. Lots of pics will help others know what your up against.

Jess

Where have you been????

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start getting ready to pull engine this weekend,will know more about the condition of bearing when out.I know it's the main brg. becouse engine knocks loud when idle can here sound at the bottom end but rev up some it dosen't knock faster like a piston or rod, oiling has been real good on this motor my dad and I modified the oil pan to hold 8 qts.thinking it could be a detonation problem,but it is always good to get input from other people I'll let you know how it turns out,and if all could give imput on it it would be appreciated.thanks robert

If the vehicle has an automatic transmission, you may want to check the torque converter to flexplate bolts, those can loosen-up and cause noise that sounds like bottom-end bearing trouble.
DD

thanks for the reply it's a manual but i'll check the clutch bolts just in case.

When you rev it up it doesn't speed up the sound of the knock?

Does it get quieter? Put a mechanic's stethoscope to the block. Is that where it is? What's the condition of your motor/tranny mounts? Exhaust system? Is it the same when you depress the clutch?

CJ

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Part of Tyrde-Browne Racing

I also had a balancer split along the keyway once and it sounded just like a rod knock.

Lou

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Home of Slant6-powered fun machines since 1988

hi, i'll check the balancer this weekend,the mounts,exhaust are new engine is torque straped.the knock sounds about mid block but a sound can telescope front to back or back to front.did not run engine very long only a couple of minutes luckily it was in the back yard and not on the bridge like what happened to the original motor when the oil pump broke at 60 m.p.h.thanks all robert