Scored Main Cap Bearing - Ouch

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Max1196 said:
In post #13, the rear-most portion of the crank looks discolored (as in turning purple from heat), if those bolts rubbing on the back of the block caused that amount of strain, the front face of the thrust bearing (#3) will also be chewed to ****, there's your engine contaminant. The heat from those rubbing bolts would also have melted the rear seal! Take #3 cap off and see what damage is done to the thrust surface of the crank.
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Its just the pic on the discoloration. The surface color is normal. I will remove the thrust bearing and post a pic.[/QUOTE]
 
At first I thought you might be fine with a bearing check and maybe a light cleanup on crank, but after reading thru, I gotta agree with pulling it.
At this point its gaskets and crank bearings.
When the shop said order bearings....is that them paying or you? I think that will tell you right there if they are going to stand behind their work.
 
4spdragtop said:
At first I thought you might be fine with a bearing check and maybe a light cleanup on crank, but after reading thru, I gotta agree with pulling it.
At this point its gaskets and crank bearings.
When the shop said order bearings....is that them paying or you? I think that will tell you right there if they are going to stand behind their work.
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No I need to pay for bearings. I just looked at the #3 main (thrust). I can get a .012 feeler gauge between the throw on the rear side and my smallest .002 wont go in on the front side. I'd say I'm screwed at this point.
 
Well that flat out sucks. Still just bearings at this point. Same shop for all machining and assembly, start to finish?
 
You need to use a very fine round stone or fine round carbide burr and chamfer the oil holes. Doesn't need to be a .250 wide chamfer, but an .062 chamfer is plenty.

Then the crank needs to be polished.

Whenever you see the center of the bearing look like that, you can bet the oils holes didn't get a chamfer.

Also, I'd tell them to do the line hone and set the clearances. That is the only way to do it correctly.

And buy the correct flywheel bolts. Only use the ARP Pro Series bolts with the hardened parallel ground washers. Lock tite is your friend and never use a lock washer on a flywheel bolt.
 
Oldmanmopar said:
That thrust bearing is shot if there was that much pressure on the bearing from the bolts rubbing the cap . There was no oil clearance on the thrust side. Listen All BS aside pull the motor . turn it upside down and pull the crank pushing the pistons to the top of the bore. You will need a timing gasket set and a oil pan set. and bearings, Recheck all the clearances on the crank and replace all the bearings and the oil pump.

You will not be sorry for doing this. You can take the crank and have it polished. Have it mic'd King and Clevite sell bearings to any size to bring the clearances in. My son just bought a set to make up .002 on the recommended clearance. If you need the right bolts for the flywheel or flexplate buy them. Or give me your address I'll send you some. Pay the shipping after you receive them.

Put a dial indicator on the crank and move it front to back you'll see that thrust bearing is bad. Also you won't drop the crank enough to do the work with the trans in and the timing chain on. Why ruin what may still be good . Do it right.
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Not the most popular advise but it is the best. Just got an engine reinstalled that I tried to shortcut while still in the truck and in the end it had to come back out. May not look like it now but will give you better peace of mind.
 
blewbyoutobad said:
Its just the pic on the discoloration. The surface color is normal. I will remove the thrust bearing and post a pic.
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[/QUOTE]

Yeah, post a pic of the thrust sides of the crankshaft. The rear side might still be ok. The front side may be gouged. Some bearings are steel backed and will damage the crank.
 
The strange thing is this flywheel and bolts came off the 340 that was in the car before this motor and no interference problem. Just goes to show never ever take anything for granted, and I am pretty good about that because as a manager I always preached that to my employees and look for train wrecks.
 
If you do a lot of in town driving you might consider taking the trans out of gear and letting the clutch out at stoplights.
Once you get in the habit your crank thrust surface will thank you for it.
Idling at lights with the clutch depressed is terrible for that surface and bearing.

Then when you are ready to go again press the clutch and drop it in second and then to first and take off.
Putting the shifter in second gear before first stops the gears from free spinning so you don't get a crunch when going into first quickly for the take off.
This works really well for non syncro first gear transmissions.
 
Good driving tips!
Years ago I discovered i could easily push shifter into neutral WITHOUT depressing clutch while off the gas approaching a traffic light. Mainly did this to save wear and tear on me, but yeah saves wear on the clutch linkage and thrust bearing too.
For years E-booger has advocated bypassing the factory switch that forces you to depress the clutch pedal before engine would crank. He believes that the oil film at the thrust bearing is minimal till engine spins a few times especially if the car has sat for any length of time.
 
sccachallenger said:
Good driving tips!
Years ago I discovered i could easily push shifter into neutral WITHOUT depressing clutch while off the gas approaching a traffic light. Mainly did this to save wear and tear on me, but yeah saves wear on the clutch linkage and thrust bearing too.
For years E-booger has advocated bypassing the factory switch that forces you to depress the clutch pedal before engine would crank. He believes that the oil film at the thrust bearing is minimal till engine spins a few times especially if the car has sat for any length of time.
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Interesting for sure. I always crank mine in neutral but it's not new enough to have a safety switch.
 
good tip on that safey switch
I'd chamfer the arting lines from thre grove to the rear
of course i drill through the thrust if i had it apart
make a little pocket on the face
next time I think I'll try a little diagional banana groove
 
Well guys all great tips. Yes I drop in neutral at lights and starting. Here's some pics of the thrust bearing. Im getting ready to hit the panic button on the first pic. Amazingly the thrust side of the crank has survived.

KIMG2830.JPG


KIMG2831.JPG


KIMG2832.JPG
 
blewbyoutobad said:
I think its time to rebuild. What do you all say?
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If it was mine for sure it would be getting rebuilt. But then again that's easier to say if you do your own building. How do the sides of the pistons look? How about the cylinder walls. I'm thinking a quick brush hone, I would clean the piston sides up with grey Scotchbrite cloth, send the crank out to be polished, knock EVERY single plug out, scrub, scrub, SCRUB, the block. And go from there on whether you want to take it on or hand it off to a shop to rebuild it for you. Summers coming.
 
Ive always sent the shortblock out, and here again my problem but I created it, but As long as you guys are around to help I'm not afraid to tackle the rebuild. Less than 500 miles on this mtr. I did see some wear lines on the cylinders from underneath, probably the trash that came off the bearings. Ok so let me ask this, bear with me. In my shop I have the original shortblock mtr (not really but was put in the car in 1975 spun a rod in original mtr). It has TRW forged piston and some rod oiling mods, flash removed from valley etc. This mtr in the car now has KB hyper piston. So if I wanted to take the semi original mtr and build a stroker should I do a 416 or 372. I had a 372 in my Valiant that made 550/500 roller cam mtr and that car would rev so fast with the 4:30 gears you better be on your game. I shifted it a 7K and it is still running today after 14 years. Sold it to a friend in NY. I loved the way it ran, but a slower rev mtr with more cubes and torque might make more sense for a 4 speed car. The Valiant was automatic. Cost is a big factor as I and my wife are retired and live off SS, but I think I could do it. The other restriction is the X heads that only flow max 260 at 525 lift. Dont know if they would support 416ci. What do you all think? The Valiant had a Mopar Perfromance 3.58 cast crank and they are about $425. Need rods and pistons also. Go Scat or what?
 
I vote for post #72.... with the addition of a new oil pump. Any metal in the oil will chew on the pump, as it is before the filter.

The current bores may be fine. Examine first IMHO.
 
if you do pull it dow do the drill thru the thrust into the oil feed about .040 the through the the bearing open up to ,061 and i'd try a dremmel and banana grove the thrust face but not off the outside edge inside is fine or just use a round ball to make the oil pocket
run the large thrust face bearings if you can
I convert blocks when i line bore
 
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