1987 V10 Engine Block Question

[JohnnyPopper]

At this point I would at least use some plastic gauge to verify the actual wear.

With that data, you can determine if it's worth it to go further.

FWIW, if it ran strong, didn't smoke or rattle or clack, I would run it till things change.

If the wear is heavy, I would probably change out the bearings. I know someone is going to flame me for not suggesting polishing the crank. 

[whipper.snapper]

Okay noted,
 
Is it possible to replace crank main bearings without removing the crank and removing all of the pistons/connecting rods? If so how?

I am thinking I am going to replace just the crankshaft bearings because the connecting rod bearings are still solid no play in them. So it would be ideal if I can replace the crank bearings without having to disturb the rods and stuff.


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[JohnnyPopper]

Yes it's possible.

Pull all of the caps off, you'll notice one end of the bearing has a flange that is keyed into the block and caps.

Push the opposite end of the bearing down into the journal, careful not to scratch the crank. (stiff plastic spoon)

Once the key is exposed you can slide it over the crank journal and pluck out.

It might help to apply a little lift to the crank, careful where you apply pressure.

Slip new bearings in opposite way.

[whipper.snapper]

Okay sweet, I watched some YouTube as well, and saw techniques very similar to what you just mentioned, so I’m gonna give it a shot.

Would you suggest I need to check the bearing clearances with plastigauge to ensure I have the correct amount? Or should I just check the back of the bearing for what size it has stamped on it and buy replacement of the same size and roll with it?


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[JohnnyPopper]

Plastigauge will only show how much the bearing has worn, which would account for most of the clearance.

If you're going to change out the bearings, it's just an academic exercise.

The size/oversize will be stamped on the back.

[whipper.snapper]

Okay, I checked the size and I believe it is .040 thousandth undersized.
I am going to attach a picture of the back of the bearing.

Would you agree it is .040 thou. Undersized?


 Thanks Johnny P.!!!! And others.


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[JohnnyPopper]

Sure looks like it!

Just as an academic exercise, which is 'undersized', the crankshaft or the bearings? 

When they grind the crankshaft, they remove material, making the main journals 'smaller'...

So they have to 'grow' the thickness of the bearings to make up for the difference.

.040 is referring to the size of the crankshaft main journals being 40 thousandths undersized.

Easy to get the two mixed up...

Having said that, if it were mine, being this deep in it, I would do the rod bearings as well.

[whipper.snapper]

Initially I was saying it incorrectly, but when I went to buy the new main bearings it dawned on me it. Haha.

I sure have learned a lot because of this engine.

Thank you for the correction on that!

I just got the new bearings installed and the motor turns over smooth as butter, so it’s Re-assembly time. And then a fresh coat of Chevy orange on her.


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[JohnnyPopper]

Nice!

Look forward to your progress. 

[whipper.snapper]

I’ll make sure to post some updates in here.

Most likely will have more questions too…. Haha


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[whipper.snapper]

Hey guys, I have a quick question…

What spark plug should I be running for my motor that we talked about above, 69-80 350 SBC..

The plugs that came out of it are ACDELCO R45T, but I am having a hard time finding those for sale.


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[bd]

R43CTS

[whipper.snapper]

Okay, is that one any different than the R45T? I just don’t know how to make sure I’ve got the right one.


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[Captkaos]

R - Resistor
4 - 14 mm Thread
5 - Heat Range (range 1-5, 1 being colder, 5 being hotter)
T - Taper Seat
S - Extended Tip

[whipper.snapper]

Thank you


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