To bore or not

WAYNES WORLD

WAYNES WORLD

New member
Guys,

This has been brought to my attention--------
Should I bore a 12 valve block or not?
I have a machine shop that sites NO-------
What is your opinion?

WAYNES WORLD
 
Uh... care to give a little more info?
Your machine shop sounds sketchy.


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I would not be worried about your machine shop as much internet know it alls the marks in your cylinder are not a problem a bore gauge is the best way of knowing if the bore is ok not an eyecrometer the marks are due to distortion and uneven wear but probably won't matter if a ball stone hone was used u wouldn't see it but the low spot would be there with out measurements like out of round and taper you can't make that call from a picture. IMO boring it over the small amount that an oversize piston is will have little or no effect on strength.
 
I'm pretty sure the internet know it all types in the other thread agreed to run it and move on with life?

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sorry you are right I should keep my mouth shut I just get tired of seeing every one second guess the shops they choose and guys on the net seem to be fast to blame the shop of making mistakes
 
Hell I assumed this was in reference to a whole different engine. I thought it was decided in the other thread that block was fine...


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He's got a thread on the other Cummins site and the precision machinest there are going bonkers about it.
I didn't exactly like the ring grove shadow in #3 but I've put engines together with bigger eye brows.
 
I'm still trying to figure out how a 12v block is prone to breaking at .020 over at any power level below at least 900hp? I've had many, many 12v blocks bored and haven't had any break. The engine in my vette is .040 and I put it in a tractor for a year and it's just fine. I know of a 12v block that was bored and put sleeves in it. It broke but that engine had catastrophic failure and the block shouldn't have been reused. I wouldn't be afraid of boring one for what you're doing.

Does your machine shop use a torque plate? They should if they make claims like this one about blocks breaking at .020.
 
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I guess I'm jaded by putting engines together in all sorts of messed up circumstances. I guess there is something to be said for surgical accuracy (precision is not the correct term) but OEM is hideous in terms of perfection on production parts. Hell, Perkins uses 4 different length rods in the same engine. They all run a long time.


I'm not knocking anyone here, so don't take it the wrong way.



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WAYNES WORLD said:
Guys,

This has been brought to my attention--------
Should I bore a 12 valve block or not?
I have a machine shop that sites NO-------
What is your opinion?

WAYNES WORLD
Click to expand...
For what it's worth: Out of the countless Cummins B blocks that I've finish honed(Sunnen CK-10; old school!), I'd say 65-70% of the blocks cleaned up perfect by only removing .002" which is where I liked to run them anyway.
 
BRE,

Kindly read on-----Eyebrow cylinder-------

Win slow,

The machine shop liked the cylinders after they finished. But facts & figures were not given me. That's part of the issue.

biggy238,

I've been told that many times.

Win slow,

I question my results because I'm not a professional. I also want to learn. Isn't that why we ask questions?

Destroked 450,

I've been told to just put it together. I wasted my summer eating for it. Now the money is getting very tight, but I'm still concerned.

DieselWrencher,

The answer from the machine shop------due to extreme pressure from the above 1,000 HP, flexing takes place on a large scale. The higher up you go the more flexing takes place.

biggy238,

Just like everybody who walks this earth, nobody is perfect. The same can be said for our motors that we try to tear apart every time we mash our trash.------

mhuggler,

Thank you-----

WAYNES WORLD
 
Two ways to look at imperfections/shortcuts or whatever you want to call them when assembling an engine or anything really:

-Run it and more than likely be fine.

-Run it and if you do by chance have an issue wonder if it was the imperfection and constantly question your decision to run it.

At the end of the day there is way more room for error in an engine than an inexperienced person may think but that is not to say you can be a sloppy hack and get away with it.

You can run it like it is and question the eyebrow or you can bore it and question the strength of the cylinder wall. Run it and move on if it were mine. Only reason the eyebrow is visible is because it was rigid honed. Lots of people dingle ball their engine so they don't see the imperfections.
 
Run it, bore it, or toss it and get a different one. Me personally being the perfectionist I am would find a better suited block. It took me a lot of trips back and forth to the Machine shop with my build to get it exactly the way I wanted. Even had to argue measurements with the machinist. But in the end they made it right and it came out how I wanted.
 
zfaylor,

Thanks for your info---------I'll run it like I stole it----

Cflanery88,

I wish I could be as good as you in this build. I think I'll try this setup. If I ever do this again I'll have better info on the machine work. If costly to learn on the fly. Thanks,

WAYNES WORLD
 
I really think the issue was a lack of communication on the part of the machine shop.

My machine shop isn't quick or particularly modern, but if there is an issue or concern they put it to the side then call me and ask what I want to do about the issue. IE how much to take off a cylinder head deck because of shadowing, or whether or not to go farther on a block because of pitting etc.

I'm sure if the machine shop called and said look the block didn't clean up all the way but you're probably better off running with some bore imperfections than going .020 over then at least the choice would have been the OP's.
I honestly would have had to of gone to the machine shop to check it out in person before proceeding. As a matter of fact I've got to run by there this week to check out a marine SBC I'm having bored over.
 
gman99 said:
I really think the issue was a lack of communication on the part of the machine shop.

My machine shop isn't quick or particularly modern, but if there is an issue or concern they put it to the side then call me and ask what I want to do about the issue. IE how much to take off a cylinder head deck because of shadowing, or whether or not to go farther on a block because of pitting etc.

I'm sure if the machine shop called and said look the block didn't clean up all the way but you're probably better off running with some bore imperfections than going .020 over then at least the choice would have been the OP's.
I honestly would have had to of gone to the machine shop to check it out in person before proceeding. As a matter of fact I've got to run by there this week to check out a marine SBC I'm having bored over.
Click to expand...

gman99,

I wish I had your machine shop doing my work.
But you are right about the boring. As stated before, they stated the flexing would be too great after boring. I talked to the machinist on the phone.
I appreciate your discussing with him.
Let me know,

WAYNES WORLD
 
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