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Re: 440 source bears off
[Re: Monte_Smith]
#1954805
11/20/15 11:54 AM
11/20/15 11:54 AM
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Joined: Jun 2008
Posts: 3,916
usa
lewtot184
master
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master
Joined: Jun 2008
Posts: 3,916
usa
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check the main bores with a dial bore gauge to make sure they're per spec and especially not out of round. the vertical measurement on the last two blocks i checked was awful, the horizontal was in spec; basically egg shaped bores. this will screw up bearing clearance.  Identify the problem accurately first before trying to correct it  Take the block (and crank)to a good machine shop if you don't have access to a good dial bore gauge and outside micrometer  I agree with all the other posts about having .004 crank to bearing clearances dry is way better than having .0027 or less dry same thing on the rod clarnaces, a little looser will last a lot longer than a tiny bit to tight will  Took the block and rotating assembly to a machine shop. Block was line bored. They found the same thing, I would like to have.027 clearance than .004. WHY?.........that's too tight for anything other than a stock rebuild and I personally wouldn't even do one of those that tight i ask: why .004" on the mains? i don't agree with .004" on the mains unless it's some kind of extreme racer.
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Re: 440 source bears off
[Re: 68dodge]
#1955191
11/21/15 01:37 AM
11/21/15 01:37 AM
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Joined: Feb 2003
Posts: 12,675
Columbia, CT
moper
I Live Here
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I Live Here
Joined: Feb 2003
Posts: 12,675
Columbia, CT
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What did you have for taper? I've run about 6 Source cranks of various strokes - not a one had zero taper. Clearances were acceptible for what the engines were doing but saying everything was perfect would be way off reality.
Well, art is art, isn't it? Still, on the other hand, water is water! And east is east and west is west and if you take cranberries and stew them like applesauce they taste much more like prunes than rhubarb does. Now, uh... Now you tell me what you know.
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Re: 440 source bears off
[Re: Monte_Smith]
#1955243
11/21/15 09:03 AM
11/21/15 09:03 AM
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Joined: Jan 2004
Posts: 13,247
Mt. Vernon, Ohio
dartman366
I Live Here
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I Live Here
Joined: Jan 2004
Posts: 13,247
Mt. Vernon, Ohio
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I didn't say that I would shoot for .004, what I said was that .0027 was too tight.........at least in my opinion anyway. I never put anything up tighter than .003, even a stock rebuild I agree with Monte and sc4400 on the clearances, my small block is at .003 all the way thru.
Light travels faster than the speed of sound,,,this is why some people seem bright untill you hear them speak.
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Re: 440 source bears off
[Re: 68dodge]
#1955263
11/21/15 10:55 AM
11/21/15 10:55 AM
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Joined: Jan 2003
Posts: 9,996
Frostbitefalls MN (Rocky&Bullw...
gregsdart
master
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master
Joined: Jan 2003
Posts: 9,996
Frostbitefalls MN (Rocky&Bullw...
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What was the end result after the trip to the machine shop? If they line bored it, they may have had room to tighten up the main bores a bit, reducing the total clearance on any set of bearings you try. There is a spec for loose to tight, and tight (on the bearing bores, not clearance!) is better for better holding power so the bearings don't spin.
Spec for the main saddle bores is 2.9425 to 2.9430. If your block was at the high side, you can reduce bearing clearance by .0005 by tightening it up to the low side when line boring.
If the block required a fair amount of work to get to spec, the crank to cam distance can change also, requiring a shorter timing chain set. They come in .005 under, and .010 undersizes.
Last edited by gregsdart; 11/21/15 11:47 AM.
8..603 156 mph best, 2905 lbs 549, indy 572-13, alky
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