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Join Date: Jun 2006
Location: Ballston Spa, NY
Posts: 528
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Rod to pump clearance
What's the general though on the adequate amount of clearance between the big ends of rods 3,5,6 and the oil pump housings when dealing with aftermarket rods. .010"? .020"? More? I don't recall ever seeing a proper spec for this clearance.
Just a curious though after having to do this on an M96.70 I'm building here.
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Adam Hennessy |
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08-20-2011, 06:18 PM
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Smart quod bastardus
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Rule of thumb in the industry is 5mm clearance between moving parts.
Thats 0.200 inches. My best guess.
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1979 930 Turbo....3.4L, 7.5to1 comp, SC cams, full bay intercooler, Rarlyl8 headers, Garret GTX turbo, 36mm ported intakes, Innovate Auxbox/LM-1, custom Manually Adjustable wastegate housing (0.8-1.1bar),--running 0.95 bar max ---"When you're racing it's life! Anything else either before or after, is just waiting" |
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08-23-2011, 12:06 PM
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Join Date: Oct 2003
Location: Central Fla
Posts: 1,864
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clearance
On Carrillo and the big engines they are very close and usually need machine work, I try to get at least 1mm at the closest point, take the pump apart to modify it so you don't crash through, Just did that on a 997 GT2 with Carrillos last week
Mike Bruns
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The two most useless things to a driver are the braking distance behind you and nine-tenths of a second ago. |
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08-23-2011, 12:15 PM
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Location: Ballston Spa, NY
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I've always set the clearance around .025", and haven't had an impact yet(or that I know if
 ). I just was thinking about this and it popped into my head to ask the motor builders here what they though as I wasn't sure if I had been taking too much off or not doing enough, although I've never carved through a pump doing the procedure.I'll start clearancing these out a little more then if the assumption is ~1mm/ .040". 5mm would be a stretch, likely wouldn't be any pump left at that rate. The impact point on the Carillos, at least in the M96.70, is right at the cap transition from the side of the cap to the bottom radius. It's also right where the thread bore for the cap bolt is and I've never been one to remove the material from the rod in that region, even when balancing the rotating assemblies. Good to know though. Thanks for the input.
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Adam Hennessy |
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08-23-2011, 06:39 PM
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Hi,
We had that issue with the overhaul of a '93 965, 3,6 Turbo. The first oil pump above ont he pic is from a regular 930 3.3 Turbo The second under that is from a 3.6 Turbo with much more clearance on the rod/pump space. Hope it helps you some way. Grtz Wim 
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911 3.0 RSR, white shell 911S 1974 911 2.7 Carrera 2.7 euro 1974 930 3.0 turbo 1976 |
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08-25-2011, 02:05 AM
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Herman the German
1974 Porsche RSR
