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Author
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Topic: Help ASAP! Main bearing clearance? Is it o.k.?
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BLstangin
Gearhead Posts: 324
From: South Central MN
Registered: Apr 2002
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posted 07-31-2003 01:21 PM
   
Well my dad and I got a start on building my 302 yesterday at last.  Here is the question. I used the original crank out of the motor. It is a 1970 motor. The motor had 92,000 miles on it when pulled. I just had the crank polished and was planning on using std bearings. We put the crank in and plastigauged every main. The front one was right around .002 and the 3 center mains were around .002-.0025 The rear main was at around .003 I am running a high volume melling oil pump with a hardened oil pump drive shaft. Are these clearances tight enough for a new motor? The motor will see 6300 rpm occasionally. I am using clevite 77 bearings. Are they a good street/strip bearing?  Alex your gudiance would be greatly appreciated along with everyone elses. Thanks, Brandon. Oh ya, hopefully we will be able to get a could of pistons in tonight so I should be able to get connecting rod bearing clearances to! ------------------
1970 coupe restored with the help of my dad. 302 with 600 holley, aluminum intake, headers, pertonix ignitor 2 with matched coil, lakewood bellhousing, 4-speed toploader, and 2.79 open 8" rear. Soon to be 9" 3.50 trac-lok
1986 f-150, 5.0, factory towing package with original c-6 trans
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bluestreek
Gearhead Posts: 1235
From: Athens,GA
Registered: Jul 2001
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posted 07-31-2003 02:51 PM
You can get .001 oversized bearings if you think you need to tighten them up a little.
What about your thrust bearing clearance? Too much movement can be bad for the life of all the other bearings. ------------------
1966 Mustang Coupe: Custom glass hood and BIG scoop sits atop a 289 stroked to 331 c.i., Steel crank and girdle, 5.4 H-beams, Forged slugs, TFS alum. heads, ported Stealth 8020 intake, Xtreme 274 Solid Roller, Holley 750 HP, long tubes, 4speed, 9" 3.50 posi.
11.86 @ 116 mph (7.62 @ 93 mph)full street trim!
DanH
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BLstangin
Gearhead Posts: 324
From: South Central MN
Registered: Apr 2002
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posted 07-31-2003 03:57 PM
There is .006 of endplay, so I think that is o.k. ------------------
1970 coupe restored with the help of my dad. 302 with 600 holley, aluminum intake, headers, pertonix ignitor 2 with matched coil, lakewood bellhousing, 4-speed toploader, and 2.79 open 8" rear. Soon to be 9" 3.50 trac-lok
1986 f-150, 5.0, factory towing package with original c-6 trans
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Buster
Gearhead Posts: 695
From: Orlando
Registered: May 2002
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posted 07-31-2003 05:42 PM
.006 is goodbtw, make sure the crank is round as well. I don't use plastigauged.... but I guess you could turn the crank in 1/4 turns to see if it's round. [This message has been edited by Buster (edited 07-31-2003).]
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kid vishus
Gearhead Posts: 4384
From: middle of NC
Registered: Oct 2000
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posted 07-31-2003 05:45 PM
Clevitte's are good bearings. I run the "P" series bearings (regular old clevittes)in my race motors without any problems. They will be fine in your street/strip car.
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BLstangin
Gearhead Posts: 324
From: South Central MN
Registered: Apr 2002
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posted 07-31-2003 07:49 PM
Ya, these bearings are supposed to be the tri-metal ones, KV is that the "P" series?------------------
1970 coupe restored with the help of my dad. 302 with 600 holley, aluminum intake, headers, pertonix ignitor 2 with matched coil, lakewood bellhousing, 4-speed toploader, and 2.79 open 8" rear. Soon to be 9" 3.50 trac-lok
1986 f-150, 5.0, factory towing package with original c-6 trans
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RonnieT
Gearhead Posts: 585
From: Port Allen, La. 70767
Registered: Jun 99
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posted 08-01-2003 09:09 PM
According to the book the clearances are a little big. The book I have shows the clearance to be .0005 to .0015 on all the mains up to 71, then the spec opens up from .0005 - .0024. You might want to mic the crank journals and see if they are undersized, they should be 2.2482 -2.2490. Well I just went over to the Clevite site and see they offer a bearing with .001 additional clearance, and that is about what you are showing, so your clearances should be good. Forgot,
Here's a link to the Clevite site
http://www.engineparts.com/motorhead/techstuff/brgselec.html Some good reading on thier site. ------------------
Ronnie
69 mach1 351W-4V engineless at the time!
70 Torino GT 351C-4v with a "shaker"
Mustangs and More Member #23 [This message has been edited by RonnieT (edited 08-01-2003).]
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