Re: 4.250 counterweight clearance
[Re: Uberpube]
#2869534
01/05/21 10:48 PM
01/05/21 10:48 PM
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Joined: Aug 2003
Posts: 43,352 Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
Posts: 43,352
Bend,OR USA
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How much end play, thrust bearing to the crank thrust flange, does it have now?
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: 4.250 counterweight clearance
[Re: Uberpube]
#2869573
01/06/21 03:20 AM
01/06/21 03:20 AM
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Joined: Aug 2003
Posts: 43,352 Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
Posts: 43,352
Bend,OR USA
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I honestly do NOT know how much to little clearance is on the crank counterweights I shoot for .030+ on the rotating crank and rod parts on what I can see and measure, look and learn A lot more clearance is way better than a tiny bit to little A good rotary hand grinder with good carbide bits is is your friend
Last edited by Cab_Burge; 01/06/21 03:21 AM.
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: 4.250 counterweight clearance
[Re: Cab_Burge]
#2869616
01/06/21 10:22 AM
01/06/21 10:22 AM
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Joined: Jan 2012
Posts: 2,691 Stuttgart, Arkansas
rickseeman
master
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master
Joined: Jan 2012
Posts: 2,691
Stuttgart, Arkansas
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They will probably have to cut the counterweights down when they balance the crank for today's lightweight rotating assemblys but still .005 sounds tight.
2011 Drag Pak Challenger
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Re: 4.250 counterweight clearance
[Re: Uberpube]
#2870292
01/07/21 10:10 AM
01/07/21 10:10 AM
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Joined: Jan 2003
Posts: 17,926 S.E. Michigan
ZIPPY
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 17,926
S.E. Michigan
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Thank you very much for the info.
I think it is great to check things out and post the info, it's not like these are secrets or anything. Posting things like that is a pretty thankless task but it helps others out.
I've tried to do that when I had the chance and years later had someone mention it, but it tended to happen more often when information was actively archived instead of allowed to die after 2 years as it is currently.
Maybe some of the perception that people take these out of the box and throw them together is caused by folks not always giving credit to those who were hired to do the build and make all the decisions... Or, even when credit is given, small details like this might not have been documented. That's my fault for wasting time trying to guess stuff like that....there is no accounting for human nature.
It doesn't really add much to the conversation but I had tons of room in this World iron K1 4.500. I think I eyeballed it somewhere near 1/4"/not worth measuring.
Rich H.
Esse Quam Videri
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Re: 4.250 counterweight clearance
[Re: Uberpube]
#2870344
01/07/21 11:15 AM
01/07/21 11:15 AM
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Joined: Nov 2004
Posts: 3,544 Syracuse,NY
CompWedgeEngines
master
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master
Joined: Nov 2004
Posts: 3,544
Syracuse,NY
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.050-.060 is preferred safe clearance. Always do the counterweights when you can, much better way. ( all depends on bob weights too)Also, if you just go all crazy with a die grinder and dont do a good job of working that down, and smoothing it all, every one of those marks is a potential stress riser, aiding to a crack down the road.If you can see a sand mark, or heavy gouge, its a stress riser.
RIP Monte Smith
Your work is a reflection of yourself, autograph it with quality.
WD for Diamond Pistons,Sidewinder cylinder heads, Wiseco, K1 rods and cranks,BAM lifters, Morel lifters, Molnar Technologies, Harland Sharp, Pro Gear, Cometic, King Engine Bearings and many others.
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Re: 4.250 counterweight clearance
[Re: 440Jim]
#2870490
01/07/21 03:00 PM
01/07/21 03:00 PM
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Joined: Jan 2003
Posts: 16,934 NC
440Jim
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 16,934
NC
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I would have the crank counterweights reduced. Even just a bevel on the edge where you need clearance. Calculate your bobweight (estimate) from the parts you will use. Check with Eagle for the approximate bobweight that specific model crank comes with. I think you will find a lot of weight will need to be removed from the crank.
For example: Piston 564.0 .990x2.93x.185 Pin 178.5 Spiro locks 4.5 Rings 45.0 I-beam small end 247.0 Con rod big end 517.0 Con rod big end 517.0 Con rod bearing 52.0 Con rod bearing 52.0 Trapped oil 4.0 Bob Weight 2181 From the Eagle website, it looks like the crank should be about 2500 gram bobweight before balancing. If your actual parts produce a required bobweight around 2200-2300 grams, the crank will be full of holes from the balance shop. Unless you tell them to reduce the counterweight diameter.
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Re: 4.250 counterweight clearance
[Re: Uberpube]
#2870527
01/07/21 04:15 PM
01/07/21 04:15 PM
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Joined: Jan 2003
Posts: 31,106 Oregon
AndyF
I Win
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I Win
Joined: Jan 2003
Posts: 31,106
Oregon
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Not sure if its the Eagle crank having larger weights, or my block being thicker down there, but just checked the clearance to the machined releif area, only 0.005 to .015 clearance from web to web. By reading some other posts and forums, people usually just drop it and start torquing things down. I've never used an Eagle crank so I don't know what sort of issues they have. Molnar cranks typically drop in and clear just fine as do SCAT fully machined cranks. I've had clearance problems in the past using Mopar cranks. Typically a 4.250 crank is going to have a low bobweight so the counterweights need to turned down anyway.
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