My Next Project

[ViPER1313]

Since spun rod bearings are becoming a problem with higher mileage SHOs, it's time that I do mine. Pictures of the process will follow shortly.

[.RJ]

Where's the plastigauge and ARP rod bolts?

[ViPER1313]

Where's the plastigauge and ARP rod bolts?

Plastigauge is really a waste of time - if the clearances are out of spec what am I going to do? Grind the crank and put in oversized bearings :roll: . Besides, I'm just too lazy to use it :wink: .

ARP - do I look like I own a Civic :lol: .

[.RJ]

Plastigauge is really a waste of time - if the clearances are out of spec what am I going to do?

Well if they are out of spec and you toss the bearings in there, you're no less likely to end up with spun bearings than if you'd left it alone.

[Andy]

Well if they are out of spec and you toss the bearings in there, you're no less likely to end up with spun bearings than if you'd left it alone.

So wise so wise.

Dude, don't be a dumbass. Pastigauge. But if you're doing preventive maintenance on rod bearings, you're already one Maybe a compromise would be to get your oil tested and see if you have rod bearing material in your oil.

[ViPER1313]

Well if they are out of spec and you toss the bearings in there, you're no less likely to end up with spun bearings than if you'd left it alone.

So wise so wise.

Dude, don't be a dumbass. Pastigauge. But if you're doing preventive maintenance on rod bearings, you're already one

How do you figure? All that plastigauge will do is tell me that the crank is ever so slightly worn, and since most of the top SHO mechanics recommend not to use it because all you are doing is putting more stress on the rod studs, I think I'll skip the step. Replacing the bearings preventively is as common in the SHO world as a valve lash adjustment - it's something all owners do if they want the engines to last. Putting new bearings in will put clearances much closer to factory specs than leaving the old ones in, prolonging the life of the engine. I have yet to hear of a person who has replaced the bearings before they spun and had a spun bearing soon afterwards.

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[white_2kgt]

It has a Nascar logo on the box, they must be good, duh.

--chad

[Evan]

It has a Nascar logo on the box, they must be good, duh.

--chad

too bad raybestos "nascar enhanced" pads are discontinued!

[ViPER1313]

It has a Nascar logo on the box, they must be good, duh.

I have no idea what that is about :lol: .

[NTIman]

Plastigage= the suck. I'd still check to see if its close to specs though. Why waste all the time screwing with your car,not to do the job at least half right.

[.RJ]

Plastigauge doesnt suck - its a cheap, easy to use tool thats good for shadetree mechanics like most of us.

All that plastigauge will do is tell me that the crank is ever so slightly worn, and since most of the top SHO mechanics recommend not to use it because all you are doing is putting more stress on the rod studs

If there is a larger problem at hand it will be readily apparent - its easy to rebuild a motor if you catch problems early - its a bit harder if the rod bearing has already spun and you have a bent rod sticking out the side of the crankcase.

I have no idea how you figure spec'ing the rod bolts will put any additional wear on the studs. Since they're coming off, you might as well replace them - and they should go through a few torque cycles before you tighten them on the final torque anyways so that you get the proper stretch on the bolt.

[ViPER1313]

Alright, so I use plastigauge to measure clearances, which will tell me one of 2 things:

1. Everything is fine.
2. Clearances are out of whack.

In the first case, I install standard size bearings, no big deal.

If the clearances are way out of whack, I can now:

1. Reinstall old bearings. There is no reason to do this, as clearances will still be screwed up and the bearing will most likely spin in the near future.

2. Install the new std size bearings. This will put clearances closer to factory specs, prolonging the life of the engine.

3. Tear the engine out of the car, pull the crank, spend more money than a new motor would cost to have the said crank reground, then reinstall with oversized bearings.

1 is a stupid choice, 2 makes the most sense, 3 is impractical.

From the guy who writes most maintenance procedures for the SHO community and has over 300k miles on his motor:

"No real need to Plastigauge the new bearings. If they aren't in spec, what are you going to do? They are still much tighter than the ones you just replaced. Just make sure you torque them in stages to the proper value."

Guy with 181k on his motor:

"If you use plastigauge and find that you're the slightest bit off, what are you going to do? Grind the crank down so you can fit oversized bearings in there? If the crank journals have no damage, there's absolutely no reason to plastigauge. Put the standard bearings in and don't worry about it for 150k miles (unless you lug the engine periodically, then check them at 100k miles)"

SHOTimes opinion on the matter:

"Don't waste your time with the Plastigauge!!! It is not really meant to be used with an engine in that position (it should be on an engine stand), and if you have never used it before, it will take you more time, and probably give you erroneous results that will make you crazy. Besides, as Paul says, IF you got good results, and IF the crank was "somehow" (very, very unlikely) out-of-spec, whaddya gonna do about it? The car ran for years with standard bearings, put standard bearings in it."

I'm not using plastigauge, your opinions on the matter are well noted. It is not "incorrect" to replace standard size bearings with new standard size bearings without measuring them with plastigauge, as it is the only practical thing for me to do.

[.RJ]

ooooh internet mechanics!

You're still missing the point. It doesnt cost you much to do, and it will tell you whether the new bearings (which is what you'd plastigauge.... not the old ones) are in proper spec with the crank are not. If you are putting in new bearings and shit is waaaaaaay out of whack - you will know right there, and at that point you can either get the correct sized bearings, pull the motor out and rebuild it while it still runs, or just install them anyways and hope your shit doesnt blow up.

Your shit is certainly not going to blow up if you dont check the clearances - but its one of those easy things to do while you're in there. Those guys talk as if checking the clearances is actually going to hurt your engine, which is just downright rediculous.

[ViPER1313]

Dropped Y-Pipe (literally - I dropped it and it fell to the garage floor )


Removed Starter


Where starter should be


First sight inside oil pan


Oil pickup tube


Oil pump


Metal and RTV stuck to oil pickup tube screen. Maybe I should check the oil pan.......


Lovely, just what you want to find ::x:


Crap chilling in the oil pan - some metal shavings and some RTV from me pulling the pan off.


Girdle covering bearings


Rod caps exposed.


Close-up of crank and caps.


Heart of the engine. After 133k miles you can still see the crosshatch pattern on the sides of the cylinder walls.


Old rod bearings - top row is the bottom bearings and the bottom row are the top bearings. The tops always seem to take more abuse (most likely from the forces exerted on them during acceleration.


Typical wear for rod bearings on the SHO (this one was 115k)


Other than the metal in the pan all signs indicate the engine is in great condition. I was surprised at the shape of my bearings - most show significantly more wear than mine did. Took me longer to clean up the oil pan than it did to replace the bearings (removing gaskets / RTV sucks.) Waited overnight for new RTV to dry, engine stated right up and everything seems to be done right. Engine seems smoother at startup too (it used to knock a little.

[JohnC]

Nice work.

[Andy]

You must have access to a lift .. . call me jealous.

What was that screw looking thing in your pan?

[white_2kgt]

you should have installed a new oil pickup. that one had crap on it and what looked to be a hole.

--chad

[ViPER1313]

you should have installed a new oil pickup. that one had crap on it and what looked to be a hole.

--chad

No hole - I cleaned it up and reinstalled it with a new gasket.

[.RJ]

Nice work - those bearings look like they were pretty worn out, i'm suprised to see that with 115k miles.

[Jeff]

Those are the same bearings I am gonna use. The only ones anyone sells are those and mopar. ARP rod bolts would have been a nice touch. I was gonna get their head studs but I got Mopar Performance instead...cheaper. Anyways, good work friend. I would have gauged it just to see where you are at. But whats done is done. It would be nice to know how bad along she is (if at all) and if something might need to be done soon.