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08-19-2010, 11:42 AM
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CC Member
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Join Date: Mar 2007
Location: seekonk,
ma
Cobra Make, Engine: factory five mkIII roadster 445 fe quick fuel 750 q series,irs
Posts: 468
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Not Ranked
fe 4.25 crank and h beam rod question
i have a steel 4.25 fe crank with the eagle h beam chevy rods , the crank was not right and had to be cut. i wanted to know what is acceptable for rod clearance?
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08-19-2010, 12:18 PM
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CC Member
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Join Date: Dec 2001
Location: Louisville,
KY
Cobra Make, Engine: I'm Cobra-less!
Posts: 9,417
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Rod bearing clearance or rod side/side clearance?
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08-19-2010, 01:05 PM
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CC Member
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Join Date: Mar 2007
Location: seekonk,
ma
Cobra Make, Engine: factory five mkIII roadster 445 fe quick fuel 750 q series,irs
Posts: 468
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Not Ranked
sorry, i wanted to know what is acceptable side clearance?.
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08-19-2010, 02:04 PM
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CC Member
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Join Date: Dec 2001
Location: Louisville,
KY
Cobra Make, Engine: I'm Cobra-less!
Posts: 9,417
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I like to see about .016-.020, but I think the spec is .010-.020. However, if I were building one and it had .010, I'd have them milled a little. It's one of those things where too much is better than not enough.
How much you got?
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08-19-2010, 02:30 PM
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CC Member
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Join Date: Mar 2001
Location: E BRUNSWICK N.J. USA,
Posts: 3,841
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What is the end play on the crank??
wrench87 What is the end play on the crank? Rod clearance I like to run about .020-.025" This number is with pistons in the holes, rods set to to torque spec or pull of rod bolts. This is with a crank at .006" end play. Rick L
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08-19-2010, 05:30 PM
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CC Member
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Join Date: Mar 2007
Location: seekonk,
ma
Cobra Make, Engine: factory five mkIII roadster 445 fe quick fuel 750 q series,irs
Posts: 468
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Not Ranked
i dont know all the particulars but he told me it had .027 side clearance this is with all new parts, my crank journals were offset the crank had to be cut he said it was like they cut the crank then hardened it and the journals were distorted. i am very unhappy with this whole fe experience, you should see all the problems i had with my stage 1 heads, diamond pistons, rpm intake all poor quality. i should of just built a 427 windsor with a dart block.
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08-19-2010, 06:09 PM
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Senior Club Cobra Member
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Join Date: Jul 2002
Cobra Make, Engine:
Posts: 15,712
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When your starting from scratch with a bunch of parts your trying to assemble, new or used, "stuff happens". You could be running into similiar problems with a W block combo just as well.
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08-19-2010, 07:11 PM
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CC Member
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Join Date: Jul 2003
Location: West Bloomfield,
MI
Cobra Make, Engine:
Posts: 717
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Side clearance of .027 is high - but won't really cause any problems. I have every single one of the RPM steel cranks I use cut/fixed - I do not even bother to try them out of the box. Almost sounds like your crank grinder got a little happy with the cheeks.
I use primarily Scat components in all of my kits and assemblies - they seem to be a good deal better in terms of dimensional control compared to the other importers. There is a reason that I use all the particular parts that I do....
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08-19-2010, 08:46 PM
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CC Member
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Join Date: May 2006
Location: St. Louisville,
Oh
Cobra Make, Engine: A&C 67 427 cobra SB
Posts: 2,445
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Doesn't excessive rod clearance result in lower oil pressure or at least more oil slinging off of the crank? |
08-20-2010, 01:32 AM
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Cobra Make, Engine:
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Quote:
Originally Posted by olddog
Doesn't excessive rod clearance result in lower oil pressure or at least more oil slinging off of the crank? |
Bearing clearances and oil pressure/volume are what dictate the amount of oil thrown from the crank. Side clearance has nothing to do with it. |
08-20-2010, 07:01 AM
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Join Date: Jul 2008
Location: Driftwood,
TX
Cobra Make, Engine: Contemporary Cobra, 427 side oiler
Posts: 1,850
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Quote:
Originally Posted by steelcomp
Bearing clearances and oil pressure/volume are what dictate the amount of oil thrown from the crank. Side clearance has nothing to do with it. |
I'd like to hear other opinions on this. |
08-20-2010, 07:46 AM
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Senior Club Cobra Member
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Join Date: Jan 1999
Location: MARKSVILLE,LA.,,
Posts: 3,235
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Quote:
Originally Posted by elmariachi
I'd like to hear other opinions on this.
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me too..........
David
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DAVID GAGNARD
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08-20-2010, 07:47 AM
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CC Member
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Join Date: Oct 2000
Location: Crystal Lake,
IL
Cobra Make, Engine: Everett-Morrison, 434 cid
Posts: 977
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Quote:
Originally Posted by elmariachi
I'd like to hear other opinions on this.
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Many engines have been built with a 1.771 Honda-size rod that is .675 wide on a 1.900 wide journal. Combined total side clearance is .550". Bearing clearance determined pressure and throw-off. |
08-20-2010, 08:33 AM
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CC Member
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Join Date: Jul 2005
Location: Bartlett,
Ill
Cobra Make, Engine: Everett-Morrison LS1
Posts: 2,448
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Bearing clearance determines oil flow UNLESS side clearance is inadequte
Lots of newer very high level engines use huge side clearance however they control rod placement by centering at the wrist pin---similar to a 2 cycle with top guided rods |
08-20-2010, 09:44 AM
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Join Date: Jul 2004
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Quote:
Originally Posted by Jerry Clayton
Bearing clearance determines oil flow UNLESS side clearance is inadequte
Lots of newer very high level engines use huge side clearance however they control rod placement by centering at the wrist pin---similar to a 2 cycle with top guided rods
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In agreement with wht you stated, but to elaborate, side clearance would have to be very tight to be inadequate when you figure you have a total area of clearance of just over .004"sq. around a 2.200 journal with .0025 clearance and a .5" wide bearing. No more oil is going to pass through that bearing and come off that crank than that .0043" sq. of area will allow. Using the piston pin boss to locate and guide the rod instead of the crank journals, as mentioned before, allows narrower rods and bearings, less friction, less heat, less recip. mass, etc.  |
08-20-2010, 09:52 AM
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CC Member
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Join Date: Jul 2005
Location: Bartlett,
Ill
Cobra Make, Engine: Everett-Morrison LS1
Posts: 2,448
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and they also now make bearings in the honda diameter and us type width
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