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Discussion Starter #1
Hi,

So a while back I thought I had rod knock and I plastiguaged all the main and rod bearings. They were okay, but shortly after that I blew an oil line on a highway and barely made it to a shop where I fixed it. However I did drive with 0 oil pressure for long enough to worry, and my oil pressure was a loy lower after that.

So I decided to put new bearings in, when I discovered the bearings are 3 sizes and not "standard" like on other engines.

Is there an easy way to torque the front bearing cap bolts with the engine in?

I also discovered that 2 or 3 of the shorter outer bolts actually had the tips shear off diagonally. See picture below. My block already has cracked webs (like many others). I am going to buy new main bearing cap bolts because cracky bolts combined with cracky webs is a recipe for leaving the crankshaft in the middle of the road. Just a thought if anyone is tearing into their lower end. It'll feel better having new bolts under there with the bearings, maybe brittle bolts contribute to the problem with these engines.

634232
 

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Wow I have never seen sheared off outer bolts .... are you sure all of it came out?
 

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Discussion Starter #3
Wow I have never seen sheared off outer bolts .... are you sure all of it came out?
Yep! I really tried to find the bits of the bolts that came out with them, and I will post a pic if I do. The chunks unscrewed with the bolts, and fell right out with them. The bolts were hard to turn by hand and I suspect the pieces unscrewing with the bolt was why.

It is also interesting even though it was starved for oil for a bit only the front bearing showed any signs of galling, though it wasn't bad.

Now, I need to find a source for individual bearings for the main. All con rod bearings seemed to be the same 1.54mm or so. Aside from saying something like GMM which I assume isn't a measurement.

Here are my main bearing measurements,


From rear forward
Standard
013
Middle 026
013
013 front bearing
 

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Discussion Starter #4
Does anyone know where I can get a main bearing bolt package? Is grade 8 enough strength? I see arp makes some studs that might work but they want over 200 dollars fpr the studs alone and that's a little too rich for my blood...
 

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Discussion Starter #6
Not much out there, only ones I could find where for 1990-up

Thank you very much! Yeah, it doesn't look like the outer bolts are even listed any more. I wonder if a similar grade 8 or 8.8 bolt would work on the outer bearing caps?
 

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If you have a Fastenal Store close by you then take one of the old bolts down and ask if they have any in stock.
 
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I’ve never seen the main bolts sheared on an angle like that.I’m quite shocked to see that to be honest.I have a few main bolts here that are used that came from a 6.2 if you want them.
 

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I’ve never seen the main bolts sheared on an angle like that.I’m quite shocked to see that to be honest.I have a few main bolts here that are used that came from a 6.2 if you want them.
Thank you, but I believe the stock bolts are too brittle and possibly causing the dropped crank issues we hear about. Does anyone know the size of the outer bearing cap bolts?

I am a welder also and can weld a 1/2" socket to an extension bar, to an 18mm socket to tighten the hard to access bolts, but how will my torque change? Will it be more or less? At the bolt?
 

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I am a welder also and can weld a 1/2" socket to an extension bar, to an 18mm socket to tighten the hard to access bolts, but how will my torque change? Will it be more or less? At the bolt?
No change, if you set the torque wrench to 100lbs it won't click until until the bolt is at 100lbs
no matter how long the extension. Swivels and wobble extensions would affect the torque reading though.
 
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Looks like those main cap bolts were overtorqued. I may have some used bolts if it comes down to it.
 

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Discussion Starter #14
I rememver reading the size of the outer bolts somewhere does anyone know it off hand? Maybe I can get 10 10.9 bolts somewhere online.

Also, is anyone aware of a place where I can get single main bearings? My crank uses like 4 different sizes... I remember reading about a company that sold individuals but I also don't remember where..
 

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Discussion Starter #16 (Edited)
I'm a GEP distributor, I can get any combo of bearings you need, they are in stock, pm me a list...
Oh! Thank you! Im sorry I didn't see this post! I will contact you forthwith.

Guys the shaft length of the outer bolt (excluding head and flange) is 68mm. I am fixing on ordering m12x1.75x70mm 10.9 hardness bolts, and then m12x1.75x100mm (I read that the inner bolts are 101mm long but nobody makes a 101mm bolt unless that's including the head!) Bolts for the inner caps, 10.9 hardness and running it. I need a work truck bad.

Edit: actually I'm going to go with a 12.9 bolt because its the metric equivalent of grade 9, which is a very strong bolt. The bolts are going to cost around 70 dollars from a fastener dealer online so that's not bad. I'll feel better about the lower end issues too after that.
 

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Ya it’s too bad your so far away cause it wouldn’t be worth the shipping for me to send you a set
 

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Discussion Starter #18
Not much out there, only ones I could find where for 1990-up

Is there a difference between 90 era inner main bolts and 83 era inner main bearing bolts? Would a 1990 inner main bearing cap bolt work in my 83?
 

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Discussion Starter #19
Also does anyone know the hardness of these bolts... Flange bolts of this size are available in 10.9 (8.8) hardness that I have found. The bolts are fairly brittle in my estimation, does that mean they are harder than 8.8? There's one hardness harder than 8.8 (USA) 10.9 (Europe/metric) and thats 12.9 (metric) but I can't find any flange bolts in this hardness. The stock bolts are flanged. I just want to know if 8.8 is hard enough. I would like 12.9 but I don't see flange head bolts in 12.9 available.
 

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Is there a difference between 90 era inner main bolts and 83 era inner main bearing bolts? Would a 1990 inner main bearing cap bolt work in my 83?
They are the same bolts in my opinion.I don’t recall them being different.
 
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