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Razor Wire Militia
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what is the min. clearance you would run???? a friend is doing a stock 454 and was hanging the rods he checked them and they came in at .0015 I told him thats tooo tight but he thinks its good I told him .002 is were you want it.. so whats your take?? to tight or run it? ohh and its in a jet :)grn
 

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Lurker
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what is the min. clearance you would run???? a friend is doing a stock 454 and was hanging the rods he checked them and they came in at .0015 I told him thats tooo tight but he thinks its good I told him .002 is were you want it.. so whats your take?? to tight or run it? ohh and its in a jet :)grn
A little tight in my opinion for that journal size and application.
IMHO I think .002-.0023 for this deal would be good.
 

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Village Idiot
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3,482 Posts
Anywhere from .002-.003 is considered acceptable. I like to keep it right at .0025, but that is just me. I have seen some stock manuals that say you you can run .0015 but I would not feel comfortable running it that tight.

Paul
 

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Purpose?

Is this a pick up, or a grocery getter?. Or a boat engine?.......Factory recomendations won't last long in a boat.............MP
 

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E-7 Sheepdog (ret)
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6,834 Posts
.002 minimum.

MP, I'm running factory clearances, and running the SNOT out of it. Just spun 5,900 on the fun gas last weekend. 4 years now on the overhaul.

Factory MINIMUM tolerances would not last long in a boat. Run from the middle to the wide side of the factory tolerances, and you'll be fine.

.0015" is a recipe for spun/wiped bearings and a disaster, and subsequent new parts (crank, rods, who knows what else), in VERY SHORT ORDER.

Factory GM Hi-Perf tolerance is .002 to .003.
 

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B.A.M aka "Black Azz Mike
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I agree with Smoking LowLow.


I run .0025-.003

I have ran .002 and it was fine BUT it was a low rpm motor.
 

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E-7 Sheepdog (ret)
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If I remember my 4-year old build right, mine are all in the .0025" to .0028" range.
 

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Rule of thumb is .001 per inch of journal diameter. Your prices may vary. LOL
BB rod journal is 2.200"...this equals .0022". Mains 2.748 this equals .0027. Different builders will vary some. Usually .0002 to .0004. Depends on application, rods (steel, alum, or titanium), drag, endurance. etc.
Wags
 

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My bro had his at .002 and has the crank in the shop right now. Was turning 5800 rpm. He only had a few hours on it and had it out so decided to open it up. He knew it was a little tight but went with it(LAZY!). .0025-.003
 

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Some guy
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That's not the proper way. Extra clearance bearings are available.
Correct, if the rods are honed too large, the bearings will not have correct crush. It would be a good idea to have the rod end measured if he does not have proper tools to do it himself.
 

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E-7 Sheepdog (ret)
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That's not the proper way. Extra clearance bearings are available.
Yea, that would be the way to do it, not honing the rod end, especially to gain a full thou from .0015"
 

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Lurker
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especially to gain a full thou from .0015"
10-4 on that.

You should be able to get were you want by using X bearings. We use the housing bore size to adjust clearance all the time, but that is because we have a tollerance on our bearing clearances of +/- .0001. As long as you stay within the factory housing bore specs (for both rod and main bore) you should be fine crush wise. When using .010 or .020 bearings/crank, adjusting the housing bore is typicly the only way to adjust clearance. Just stay within the factory bore specs.
If you are worried about rod bearing crush (too much or not enough) you can check them fairly easy. First, torque the rod with the bearing installed. Then loosen both rod bolts. Next, torque one side to 120in/lbs and measure the gap in the opposite side parting line with a feeler gauge. We measure the parting line as close to the rod bore as possible. Our specs for rod bearing crush are .0045min. and .0065max. Anything less than .004 you can risk spinning the bearing just from load and housing distortion. Any more than .007 and the bearing can actualy start to buckle (causing high/low spots on bearing face). This may vary a little by overall housing bore size and rod material but should keep you out of trouble.

As always, IMHO! ;)
 

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Lurker
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NO YOU DIDN'T. There is no way you can .001 by honing the rod without losing your bearing crush, I don't care how tight they were to begin with. Why the hell wouldn't you just get X bearings and adjust as needed between standard and the X. Useing the rod bore to adjust that much is insane
That's the truth!!
 

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E-7 Sheepdog (ret)
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well, MAYBE they haven't been done yet and he has time to "stop the insanity".
 
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