Re: measuring for bearing clearnce
[Re: mopar dave]
#1928436
10/08/15 03:45 PM
10/08/15 03:45 PM
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Joined: Aug 2003
Posts: 43,269 Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
Posts: 43,269
Bend,OR USA
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You need to measure the O.D. of the crankshaft and set the dial bore gauge up with the same outside micrometer so you can see the actual differences between the two I have several dial bore gauges and inside and outside mikes, I use one outside mike to do all the measuring on the crankshaft and bearing I.D. on each motor That helps eliminate the chance for eyeball error and not every one has the same touch,feel, on using micrometers :shruggy :My .0027 might be your .0022 I like looser bearing clearances than tighter, shoot for .0010+ for each inch of diameter. I would and do run .003+ on SB cranks, mains and rods on both 318/340 and 360. Our motors are not the same as Chevys and Furds
Last edited by Cab_Burge; 10/08/15 03:50 PM.
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: measuring for bearing clearnce
[Re: mopar dave]
#1928542
10/08/15 07:20 PM
10/08/15 07:20 PM
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Joined: Sep 2008
Posts: 656 Florida
CJD AUTOMOTIVE
mopar
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mopar
Joined: Sep 2008
Posts: 656
Florida
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Was the machine shop climate controlled? Not sure if that's an issue in MI, but down here in Florida, the good machine shops are climate controlled. They bring the blocks/heads inside for a minimum 6 hours to climatize before machining. You'd be surprised how much 25 degrees makes when the machine, block, or both are above the temps the manufacturers advertise the tolerance of the machines at. I am sure you know this, but have your tools at the same room temperature as what you are measuring. And then the question is what is the quality of tools you are using? As stated above, .001 per inch is pretty much the standard, but depending on what oil viscosity you'll use, what your power level is, and whether or not your using a power adder, will dictate the ideal clearance. I do disagree about Mopar engines requiring some different clearance than a Chevy or Ford. The crank and bearing doesn't care what brand it is, the clearance will be dictated by journal size, oil viscosity, power level, and whether or not a power adder is used.
Last edited by CJD AUTOMOTIVE; 10/08/15 07:21 PM.
Craig Scholl CJD Automotive, LLC Jacksonville, FL www.CJDAUTOMOTIVE.com904-400-1802 "I own a Mopar. I already know it won't be in stock, won't ship tomorrow, and won't fit without modification"
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Re: measuring for bearing clearnce
[Re: mopar dave]
#1928724
10/08/15 11:48 PM
10/08/15 11:48 PM
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Joined: Oct 2003
Posts: 7,506 Az
Crizila
master
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master
Joined: Oct 2003
Posts: 7,506
Az
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Check a few with plasti-gage ( not very accurate, but - just to see what you get. If your readings are correct, you can buy oversize bearings if needed.
Fastest 300
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Re: measuring for bearing clearnce
[Re: mopar dave]
#1928748
10/09/15 12:20 AM
10/09/15 12:20 AM
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Joined: Nov 2006
Posts: 733 jacksonville,FLORIDA
slammedR/T
super stock
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super stock
Joined: Nov 2006
Posts: 733
jacksonville,FLORIDA
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Don't trust plasti gauge, I did and number 4 rod was bad (egg shaped) and the plasti gauge read good on all rod bearings. Well number 4 spun rod bearing in my driveway at idle, never saw more than 30 minutes total run time and oil pressure was perfect whole time. I even paid machine shop to check every thing, they had the whole rotating assembly when the bored and notched the replacement block. I even told them number 4 pumped water through it on the last pass down the track and if was even close to funny replace it. Well lessen learned, never again will I not check every thing myself with bore gauges and micrometers.
2000 Dakota R/T, 408 magnum, 727, Indy heads 1000cfm 4150 carb, 93 octane fuel. motor; 10.258 @ 132.78 200 shot; 9.262 @ 144.69 racemagnum
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Re: measuring for bearing clearnce
[Re: dthemi]
#1928785
10/09/15 01:03 AM
10/09/15 01:03 AM
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Joined: Jan 2007
Posts: 8,043 Mt Morris Michigan
mopar dave
OP
master
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OP
master
Joined: Jan 2007
Posts: 8,043
Mt Morris Michigan
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last build with this block had .002" on mains and rods using ACL bearings. now have federal mogul. will there be a noticeable difference in oil pressure going to .0035 vs .002?
Last edited by mopar dave; 10/09/15 01:09 AM.
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Re: measuring for bearing clearnce
[Re: mopar dave]
#1928800
10/09/15 01:35 AM
10/09/15 01:35 AM
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Joined: Jan 2005
Posts: 3,635 Oakland, MI
dizuster
master
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master
Joined: Jan 2005
Posts: 3,635
Oakland, MI
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I am running almost exactly the same thing you are. '91 360 block, filled with a girdle. Mine has ~.0035 on the mains, and ~.003" on the rods.
Oil pressure isn't the greatest... I have a Melling 72 pump. With the new mopar performance hydraulic roller lifters, and crane gold rockers (shaft oil)... the oil pressure isn't exactly stellar. Only has around 45~50psi hot oil through the traps at 6200~6300. I plan on shimming the pressure control valve while it's apart right now to help with that.
I just took the motor apart yesterday because I had broken a piston in it. All of the mains look great, so I can't say that the lower pressure or large bearing tolerances are hurting anything.
The only exception is the #4 main which coincidentally is right where the #4 main isn't tied to the #5 main on the girdle (because the oil pump is in the way on a small block). It has some strange wear on that cap side of the bearing where the only explanation is the crank and/or block is flexing. It has warn through to the copper, only on the front 1/3 of the bearing, only directly opposite of the #6 piston around 4 o'clock.
That being said... the last time I took this motor apart, it had the same strange bearing wear on ALL of the front 4 caps...I'm making a good 100hp more now then I was last time... so I attribute how much better it looks this time to the girdle doing it's job. But this is at low RPM (MEGA torque) and probably 150hp+ more then your plans.
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Re: measuring for bearing clearnce
[Re: dizuster]
#1928811
10/09/15 01:50 AM
10/09/15 01:50 AM
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Joined: Jan 2007
Posts: 8,043 Mt Morris Michigan
mopar dave
OP
master
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OP
master
Joined: Jan 2007
Posts: 8,043
Mt Morris Michigan
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i have a 71LA block, but yes both are 360's. are you using full groove main bearing? i'm concerned with the low oil pressure. good to hear bearings look good but one. i know the girdle requires a .005 crush. maybe i dont have the girdle shimmed properly?
Last edited by mopar dave; 10/09/15 01:52 AM.
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