Bad Main bearing cause?

Quote:

Ok so for an update, i stripped the entire motor down and noticed that there was a chunk taken out of one of the cam lobes. I'm sure the engine was dirty however i have a strong feeling that the oiling was a problem for the bearing failure. I noticed that i have a m63hp which is a melling high PRESSURE pump. Could this have been the cause of my rear main seal leak all along?

As for the bearing failure, it had that high pressure pump, no windage tray, and an el cheapo stock oil pan with baffling. Also i noticed the pickup tube measure like .6" or something, and the inlet was .56". Is this the measurements of the hemi oil pickup? I thought 383's had the smaller pickup tube. Did someone drill and tap out the oil pickup (if they did, they did a pretty good job)?

Can anyone determine if this oil set up could have been the cause of my bad main bearings? I looked around and it seems not too many people run the high pressure pumps. whats the deal with them on a semi hot street motor?

I dont remember what oil pressure it was running at, but its a 383 bored .40 over, pretty stock bottom end with speed demon 750 carb, holly street dominator intake, headman long tube headers, and full 2.5" exhaust. Yes i ran it very hard on the street.

3/8 National pipe thread,NPT, is the stock oil pump size on the 361 to 440, 1/2 inch NPT is stock for the M.W.426 and the 426 Street and race hemi motors. Not sure of the O.D. on either, sorry

Take the pump apart and look at the gear and rotor, if not tore up you can reuse it

, cut 1 to 2 coils off of the high pressure spring and reuse it, if you want more pressure after trimming the spring get some very small flat washers that will fit ino the bypass plug that holds the bypass valve and spring in the oil pump cover and install them one at a time until you get the oil pressure you want

Always check it(pressure) with hot oil, not cold oil, at idle and wound out

Posted By: VoodooCLD

Re: Bad Main bearing cause? - 03/05/12 04:06 AM

Ya, i don't really understand. The motor ran like hell before it threw the water pump. I almost buttoned it back up, but decided i wanted to lift the crank to properly install the rear main seal. It had good oil pressure, and didnt knock or anything. I guess i'll have to see if the line hone or crank is out of wack. What does a shop usually charge to check a crank, and line bore? I'm in stillwater, oklahoma if that helps.

Posted By: Cab_Burge

Re: Bad Main bearing cause? - 03/05/12 04:58 AM

Does the motor rotate over easy? If so the rings are probally sealing, even after sitting since driven the last time. Pull the heads and take a look at the cylinder walls and pistons and rings

If they look good to you it means you will need to make a decision, run it or rebuild it

Posted By: VoodooCLD

Re: Bad Main bearing cause? - 03/05/12 03:30 PM

Ya i had the heads off last week and the cylinders look fine. The engine turnes over smooth without and grinding.I'm trying to decide what to do as of now. I'm considering doing a *cheap rebuild* by cleaning it my self. having the line bore checked,bores checked, turning the crank next size, and putting in new main and rod bearings. I'm also considering keeping my eyes open for a 383 or 440 short block that's ready to run, and reusing my 906 heads. The more i think about it, the more i wanna blame poor oiling for this.

Anyone got a fresh short block for sale?

Oh ya, I've decided I'm definitely gonna bring my crank to a machinist to have him check it out. The condition of the crank will definitely determine my final approach.

Posted By: Challenger 1

Re: Bad Main bearing cause? - 03/05/12 03:34 PM

I'd say the motor was assembled very dirty from the looks of those bearings. Time for a new crank if your old one is already .010" undersize.

Posted By: VoodooCLD

Re: Bad Main bearing cause? - 03/05/12 04:27 PM

Why time for a new crank? They make bearings to .040 under.

Posted By: dogdays

Re: Bad Main bearing cause? - 03/05/12 04:29 PM

Since when did a 383 crank have inherent weaknesses that made it unusable if it had been ground more than 10 under? NEVER.

There are main and rod bearings out to at least 40 under. Racers looking for that last hundredth or two often used to grind the cranks down as much as they could get bearings to fit. The popular 3.91" stroke offset ground 440 crank, or any bigblock chevy rod stroker, has rod journals 0.175" smaller than stock.

I'd say that if your main bearings look that bad, the crank needs to be reground. Period.

And with that amount of bearing material circulating I'd say you need to take the engine down and clean out all the oil passages and everything else you can clean. You can check the taper in the cylinders and the piston fit at the same time. Don't buy any new parts, including the crank regrind, until you know what you have.

Looks to me like the engine was starving for oil. The oil pump is on the front of this engine.
The progressively worsening damage from the front of the engine to the back suggests that for whatever reason there was not enough volume of oil being pumped or else there was oil bleeding out of the system before it could get to the back of the engine.

R.

Posted By: beedees

Re: Bad Main bearing cause? - 03/05/12 04:51 PM

Either those are full-groove bearings or the uppers are installed in the lower and vice-versa. Looking again, I see they are the lowers and are f.g. brngs, looks to be excessive oil clearnce. Maybe .010 brngs. on a .o2o under shaft? I've seen it before.

Posted By: VoodooCLD

Re: Bad Main bearing cause? - 03/05/12 08:33 PM

Well i called a local machine shop. They charge $55 to cut the main bearings, and $110 to do the whole crankshaft. I'm gonna tear it all the way apart tonight, and inspect, and drop it off tomorrow to have them see if its salvageable.

Thanks for the help. I'll keep you updated.

Posted By: JSR1485

Re: Bad Main bearing cause? - 03/05/12 08:42 PM

My 360 engine out of my Duster looked just like that or even a little wrose-main cause was shifting @ 7500 rpm on over 200 runs down the 1/4 mile. What really did it in was spinning it to 8500 rpm doing a burn out when my I forgot to put a chip in the rev limiter

Posted By: VoodooCLD

Re: Bad Main bearing cause? - 03/06/12 01:21 AM

Well i got the crank out. Looks like the mains are possibly just .001 under what there supposd to be. The rod bearings were nowhere near as bad as the mains, but i could see some copper in places. I did find some metal shards in the oil pickup, but i'm not sure where they came from. I saw a few different spots on the crank that looks rather rough, and wonder if they maybee came off it. Here is a picture of a spot that looks rather shady. Its tough to tell but thats a metal curly cue, and i was able to break the top off with just my fingers.

I found a Steel crank 440, and might end up building that, but man are rods and pistons expensive.

Attached picture 7104939-photo(5).JPG

Posted By: VoodooCLD

Re: Bad Main bearing cause? - 03/15/12 04:34 AM

Ok so for an update, i stripped the entire motor down and noticed that there was a chunk taken out of one of the cam lobes. I'm sure the engine was dirty however i have a strong feeling that the oiling was a problem for the bearing failure. I noticed that i have a m63hp which is a melling high PRESSURE pump. Could this have been the cause of my rear main seal leak all along?

As for the bearing failure, it had that high pressure pump, no windage tray, and an el cheapo stock oil pan with baffling. Also i noticed the pickup tube measure like .6" or something, and the inlet was .56". Is this the measurements of the hemi oil pickup? I thought 383's had the smaller pickup tube. Did someone drill and tap out the oil pickup (if they did, they did a pretty good job)?

Can anyone determine if this oil set up could have been the cause of my bad main bearings? I looked around and it seems not too many people run the high pressure pumps. whats the deal with them on a semi hot street motor?

I dont remember what oil pressure it was running at, but its a 383 bored .40 over, pretty stock bottom end with speed demon 750 carb, holly street dominator intake, headman long tube headers, and full 2.5" exhaust. Yes i ran it very hard on the street.

Posted By: 6PakBee

Re: Bad Main bearing cause? - 03/15/12 11:13 AM

3/8" pipe is 0.675" OD.

Posted By: GODSCOUNTRY340

Re: Bad Main bearing cause? - 03/15/12 04:18 PM

Looks like the bearings get worse toward the rear of the engine. Did you ever throw a lifter from the lifter bores? This would cause a loss of oil pressure and would cause the bearings at the rear to sustain more damage than the front as they are oiled from the front to the rear. Also by the looks of the front bearing the line bore is out and needs corrected before building it again.

Posted By: VoodooCLD

Re: Bad Main bearing cause? - 03/15/12 04:38 PM

I don't think i threw a lifter at any point. Do you think maybe the line bore is screwed up due to the previous owner not replacing the main caps back in their original spot?

Posted By: Dodgem

Re: Bad Main bearing cause? - 03/15/12 05:20 PM

You don't want a 63HP they will put out huge pressure 140 + you want a 63HV gives volume at way less pressure.

Think the Hp is for industrial motors like water pumps that run 24/7 at 4000 rpm. with a canaster style filter.

took one off a friends 440 would blow the filters up and off sometimes and buried the 140 oil pressure gauge. Sharp pump gears as opposed to the rounded ones

Posted By: rhad

Re: Bad Main bearing cause? - 03/15/12 07:12 PM

dont the main caps have the number cast into them?

Posted By: VoodooCLD

Re: Bad Main bearing cause? - 03/15/12 07:19 PM

I'll have to check when i get home. I thought that there were some stampings on the caps, but for some reason i thought they all said 8. I'll double check when i get home.

On a side note, the rod bearings were worn in places as well. They were not nearly as bad as the crank bearings, but i could see a little copper in places. If the line bore was off, it wouldn't effect the rod bearings too much. So i'm again wondering if it was just dirty oil, and poor oiling, and maybee i could get away with just a replace of bearings.

going to pick up the crankshaft tonight, it got turned 20/20 with no problems.

Posted By: Oyvind Mopar

Re: Bad Main bearing cause? - 03/15/12 08:17 PM

Quote: Ok so for an update, i stripped the entire motor down and noticed that there was a chunk taken out of one of the cam lobes.

I had a 360 stroker that had same bearing issues due to 3 worn-out camlobes had sent the trash through the mains, chewed them up badly first. Rodbearings looked better.

Had to regrind the crank etc. after a full tear down. Same has happened with other engines that ruined camlobes. Just to let you know. Hope it works out for you!

Posted By: VoodooCLD

Re: Bad Main bearing cause? - 03/15/12 08:36 PM

Quote:

Quote: Ok so for an update, i stripped the entire motor down and noticed that there was a chunk taken out of one of the cam lobes.

I had a 360 stroker that had same bearing issues due to 3 worn-out camlobes had sent the trash through the mains, chewed them up badly first. Rodbearings looked better.

Had to regrind the crank etc. after a full tear down. Same has happened with other engines that ruined camlobes. Just to let you know. Hope it works out for you!

So you think i'll be alright with just turning the crank down and installing new bearings? (i'm also gonna hone, and put new rings in)

And what did you do to fix this, just install a higher quality cam? Mine looks like the original.

Posted By: Dodgem

Re: Bad Main bearing cause? - 03/15/12 09:56 PM

Interesting , just did a build with a 63HP and didn't experience any of this .

You sure you have an HP and not and HV they sell 3 stock, High volume HV and High Pressure HV.

When I went to the speed shop with the HP he said I will not sell them just HV or stock. He said his book said industrial motor only with canister type filter.

And yes I checked the bypass even put a stock spring in which did not help much at all.

Put one of my used mopar high volumes on and it was fine so then got a new HV and it was fine the gears are totally different!

Well I see the melling hp is just a stock pump with stronger bypass spring??
This one years ago had tall gears like a high volume but real sharp?? may have been a Federal Mogal bin a while but it was dangerous. took out 3 140 hp oil gauges as well as filters.

Posted By: VoodooCLD

Re: Bad Main bearing cause? - 03/15/12 10:01 PM

Quote:

Interesting , just did a build with a 63HP and didn't experience any of this .

I know you were talking to him, but mine has a tag on it that's attached to one of the bolts that says m63hp, and "cal 10" is cast in the side of it.

And dodgem means, "they sell 3 types - stock, High volume HV, and High Pressure HP"

Posted By: JohnRR

Re: Bad Main bearing cause? - 03/15/12 11:52 PM

Quote:

Quote:

Interesting , just did a build with a 63HP and didn't experience any of this .

You sure you have an HP and not and HV they sell 3 stock, High volume HV and High Pressure HV.

When I went to the speed shop with the HP he said I will not sell them just HV or stock. He said his book said industrial motor only with canister type filter.

And yes I checked the bypass even put a stock spring in which did not help much at all.

Put one of my used mopar high volumes on and it was fine so then got a new HV and it was fine the gears are totally different!

Well I see the melling hp is just a stock pump with stronger bypass spring??
This one years ago had tall gears like a high volume but real sharp?? may have been a Federal Mogal bin a while but it was dangerous. took out 3 140 hp oil gauges as well as filters.

I am 99% sure it was a HP , will have to check the invoice now ... I t did have a leak and I had to lap the plate the oil filter attaches to because it looked like it was surfaced with a rock. Standard height stock looking rotors , never seen one with the sharp rotor till someone posted the picture of the new style that is coming out?

Posted By: JohnRR

Re: Bad Main bearing cause? - 03/15/12 11:58 PM

Quote:

dont the main caps have the number cast into them?

Yes the caps are numbered.

Posted By: Oyvind Mopar

Re: Bad Main bearing cause? - 03/16/12 12:02 AM

Quote:

Quote:

Quote: Ok so for an update, i stripped the entire motor down and noticed that there was a chunk taken out of one of the cam lobes.

I had a 360 stroker that had same bearing issues due to 3 worn-out camlobes had sent the trash through the mains, chewed them up badly first. Rodbearings looked better.

Had to regrind the crank etc. after a full tear down. Same has happened with other engines that ruined camlobes. Just to let you know. Hope it works out for you!

So you think i'll be alright with just turning the crank down and installing new bearings? (i'm also gonna hone, and put new rings in)

And what did you do to fix this, just install a higher quality cam? Mine looks like the original.

I do not know how to check the material quality of the cam and lifters. It is a gamble when using stock type parts. I used another block, bored it and put in the old pistons, after removing all iron particles stuck in the skirts. Then new rings. And, using a high Zn / Ph oil and the comp cams additive as well.
The old 360 block can be reused (have it for another project) after honing, it cleared out quite well with only .001" removed. Only a few tiny stripes left.
I changed the block because of a low oil pressure issue, and suspected the lifterholes to be too slack. They were no worse than the other, but I did not take chances. The hivolume oilpump was destroyed by all the debris going through.
The engine was run for some time with the damaged lobes, and I think this extended running with the debris destroyed the engine. Camwear did not stop on the broken lobes, and finally the engine started misfiring on the cylinders with low lift. Then it was all detected when I got the vehicle in for service/troubleshooting.

I hate this situation with the cams, lifters and oil. In the past I never take chances with the oil, and use the sloppiest valvesprings possible for the cam and max rpm for these street engines.
You could use lifters with lube holes, and nitrided cams (I thought they all were nitrided, but obviuosly not good enough, so extra cash is needed to avoid being cheated) and you end up with something approaching a roller in cost. Still this could be better than a roller failure in a high mile/useage street engine.

I also had an engine with a 590 cam broken in at the dyno, checked/adjusted valves, OK, and after the dyno session one lobe and lifter was gone. I guess the oil used was not good enough, and the quality of the parts is questionable.
I am so afraid of this stuff that I rather buy a slightly used cam with lifters in sorted order, to be sure it has survived the first runs. I build engines for a living, and the profit gets negative when such things happen.

Good Luck!!!

Posted By: VoodooCLD

Re: Bad Main bearing cause? - 03/16/12 12:52 AM

Finally some real news. I took a second look at the caps, and while they were in the correct numerical order. THEY WERE NUMBERED BACKWARDS! The number 5 cap was at the front of the engine. (i believe this is backwards right?)

In any case, if i were to just get new bearings and put it back together in the correct order (1 being at the front of the engine) would it work alright? I'd really like to not have it line bored since no one here in town does it, but i don't want to be tearing down the engine again. Also are the numbers on the main caps supposed to go on the driver or passenger side?

Another thing, when i was at the shop i measured the rod journals and after machining they measured 2.354. I asked why they were 6 thousands under a .020 over, and he showed me a book that said stock journals were 2.374. I assumed that the book was right, but now every where i'm reading says that stock journals are 2.380, and .020 under would be 2.360!!!!

WHAT IS THE STOCK ROD JOURNAL SIZE ON a (cast 1970) 1971 mopar 383?
and what would a .020 under be. No websights selling bearings show the exact size.

EDIT: I have found even more sources that state the stock rod journals are 2.375". So maybee his book was right after all (in don taylors big block mopar engines, he states 2.380" and that was the first book i grabbed). And even more, they actually measured about 2.3545. So i now feel he might have done a really good job.

Posted By: 6PakBee

Re: Bad Main bearing cause? - 03/16/12 01:58 AM

You have to be kidding me. Backwards? Anyway you must have the engine out of the car? If the crank is OK, with the pan side facing up and new upper bearings in the #1 and #5 position in the block, spin the crank and check the runout on the #3 bearing with a dial indicator. Should be less than 0.001" TIR. Then put the rest of the upper bearings in and plastigauge all of the main journals. A change in clearance from one end to the other typically means a line bore job. If the clearances are close, assemble all the bearings and with lube on them check how freely the crank turns. A straight crank in a straight block requires very little effort to get it to spin. BTW, the main caps are offset and will fit in the register only one way.

Posted By: BSB67

Re: Bad Main bearing cause? - 03/16/12 03:01 AM

Quote:

You don't want a 63HP they will put out huge pressure 140 + you want a 63HV gives volume at way less pressure.

Think the Hp is for industrial motors like water pumps that run 24/7 at 4000 rpm. with a canaster style filter.

took one off a friends 440 would blow the filters up and off sometimes and buried the 140 oil pressure gauge. Sharp pump gears as opposed to the rounded ones

If that happens, it's not due to the HP pump/spring. Either the relief valve was stuck, or the pump volume was greater than the relief valve could bleed off. Of coures the motor would need to be pretty tight as well.

The HP is all I use anymore.

Posted By: Cab_Burge

Re: Bad Main bearing cause? - 03/16/12 04:24 AM

Number one main cap is in the front of the motor by the oil pump, the rod journals should be 2.375 stock, Mopar allows +.0005 or - .0005 for the factory tolerances, 2.3745 to 2.3755, .020 under should be 2.7555 tp 2.37545

Get the new main bearings and fix the crankshaft and then install the upper main bearings(the ones with the oil holes) in the block and then lay the crankshaft in them,use oil on the main bearings and crankshaft and then spin it, install the main caps so that two bearing retaining tangs are facing each other and then tighten the mains down to 85 Ft lbs, I use three increments, 30 lbs, 60 lbs and then 80 lbs. ,except number three,leave it loose until your ready to set the end play, and spin the crank. No main seal or timing cover seal yet. It should spin very easily by grabbing the crank snout with one hand and spin it

If it doesn't spin easily find out why. You can also try spinning the crank on each main bearing as you tighten them down, just in case

Let us know what you find, BTW, the main caps should not fall into the main saddles, they should have to be tapped in or push in very hard by hand

I use a soft faced mallet to tap them into place

Posted By: VoodooCLD

Re: Bad Main bearing cause? - 03/16/12 11:50 PM

Cab thank you for the info. 6pak i don't understand how checking the runout on the crank will determine if my block is still in line. Seems like that would only check that the crank isn't warped?

Posted By: 6PakBee

Re: Bad Main bearing cause? - 03/17/12 12:52 AM

Quote:

Cab thank you for the info. 6pak i don't understand how checking the runout on the crank will determine if my block is still in line. Seems like that would only check that the crank isn't warped?

You are absolutely correct. If you check the crank and the crank is true (straight), then you can use it as a try bar to check the alignment of the main bearing bores. Look at it this way, if you assemble the bottom end with new bearings and the crank is hard to turn; do you have a bent crank or does your block need to be line bored because the main bores are out of alignment? If you check as I have indicated you'll know the answer.

Posted By: VoodooCLD

Re: Bad Main bearing cause? - 03/17/12 02:50 AM

Quote:

Quote:

Cab thank you for the info. 6pak i don't understand how checking the runout on the crank will determine if my block is still in line. Seems like that would only check that the crank isn't warped?

You are absolutely correct. If you check the crank and the crank is true (straight), then you can use it as a try bar to check the alignment of the main bearing bores. Look at it this way, if you assemble the bottom end with new bearings and the crank is hard to turn; do you have a bent crank or does your block need to be line bored because the main bores are out of alignment? If you check as I have indicated you'll know the answer.

Gotcha, so as far as checking the line bore you basically just make sure the crank spins freely..

thanks