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SBC rod bearing clearance with aluminum rods
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DRR Sportsman
posted
What is everyone running for rod bearing clearance with aluminum rods? I’ve never run aluminum rods before but saw where BME states a min of .003”. Im at .0035 now and wanted to see if I was good or if I needed to tighten it up a little?

Thanks
Jason


Jason McLawhorn
Greenville, NC
1955 Chevy

 
Posts: 476 | Location: Greenville, North Carolina | Registered: March 28, 2007Reply With QuoteReport This Post
DRR Sportsman
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I would go with it. Remeber, .003 is the recommended minimum, you may need more depending on operating conditions.
 
Posts: 486 | Location: Going to or returning from the chipmine. | Registered: July 01, 2011Reply With QuoteReport This Post
DRR Top Comp
Picture of wideopen231
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apple to oranges. I run .004 on my Hemi aluminum rods .If your .0035 on .003 I would run it.I differently would not tighten it up.




America home of free. Brought to you by 2nd amendment.
 
Posts: 4173 | Location: Greensboro NC | Registered: May 24, 2011Reply With QuoteReport This Post
DRR Sportsman
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Thanks guys!!!


Jason McLawhorn
Greenville, NC
1955 Chevy

 
Posts: 476 | Location: Greenville, North Carolina | Registered: March 28, 2007Reply With QuoteReport This Post
DRR S/Pro
Picture of Big Steve
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BBC here but should not matter, bearing does not know what engine its in. .0035
 
Posts: 2409 | Location: Moving back to the door side | Registered: April 30, 2010Reply With QuoteReport This Post
DRR Sportsman
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This made me remember a saying an old dirt track racer I used to do machine work for said" build it a little loose no one but you will know. Build it a little tight, everyone will know." Kinda true if you think about it.
 
Posts: 486 | Location: Going to or returning from the chipmine. | Registered: July 01, 2011Reply With QuoteReport This Post
DRR Top Comp
Picture of wideopen231
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Yea a engine is only time loose is better than tight.LMAO




America home of free. Brought to you by 2nd amendment.
 
Posts: 4173 | Location: Greensboro NC | Registered: May 24, 2011Reply With QuoteReport This Post



DRR S/Pro
Picture of Big Steve
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Mains at .004
 
Posts: 2409 | Location: Moving back to the door side | Registered: April 30, 2010Reply With QuoteReport This Post
DRR Top Comp
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.003 turns into .0045 when aluminum rods get up to operating temperature.
The big end grows so much there's no clamping force on the bearing any longer. That's why there's a pin through the bearing to hold it in place...


.
Dave



F J B

 
Posts: 4448 | Location: Earth | Registered: February 08, 2006Reply With QuoteReport This Post
DRR S/Pro
Picture of Big Steve
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quote:
Originally posted by imakehp:
.003 turns into .0045 when aluminum rods get up to operating temperature.
The big end grows so much there's no clamping force on the bearing any longer. That's why there's a pin through the bearing to hold it in place...


Guess my .0035 is .005 when warmed up then, maybe that's why it makes such good power Big Grin . Just took my engine apart to give everything a look see, rod bearings looked like they came out of the box. Sent the Rods to MGP and they gave them a clean bill of health on both the big and little end and also said the bearing transfer to the rod was perfect.
 
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MAn my .004 rods and .005 mains is really loose.So I can spin it more.yee haa




America home of free. Brought to you by 2nd amendment.
 
Posts: 4173 | Location: Greensboro NC | Registered: May 24, 2011Reply With QuoteReport This Post
DRR Pro
Picture of rusty
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i like loose clearance also but there is always gains and losses,loose may mean low or no oil pressrure in shutdown.its ok as long as you know and precautions are taken .


honesty is the best policy,insanity is a better deffense
1.036, 6.16@ 224

 
Posts: 1391 | Location: texas | Registered: February 17, 2006Reply With QuoteReport This Post
DRR Sportsman
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IMO .0035 with an aluminum rod is fine. In fact I would be nervous about running it at .003. In my personal experience I have never seen an issue with a little too much oil clearance. I have seen issues from being a little tight.


B.J. Masiello
 
Posts: 250 | Location: Connecticut | Registered: November 27, 2007Reply With QuoteReport This Post
DRR Sportsman
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quote:
MAn my .004 rods and .005 mains is really loose.So I can spin it more.yee haa

quote:
MAn my .004 rods and .005 mains is really loose.So I can spin it more.yee haa


My old big block I was between .0038 and .004 on the rods. The bearings came out looking like brand new. That was spraying between 300hp and 600hp every run on a 572.

I was closer to .003 on the mains and they looked the same. I have zero experience with hemis don't they tend to set those up a little on the looser side though?


B.J. Masiello
 
Posts: 250 | Location: Connecticut | Registered: November 27, 2007Reply With QuoteReport This Post



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