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Broke A Main Cap!
#682077
04/27/10 08:46 PM
04/27/10 08:46 PM
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Joined: Jan 2003
Posts: 465
Oconomowoc, WI.
Cudahlr
OP
mopar
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OP
mopar
Joined: Jan 2003
Posts: 465
Oconomowoc, WI.
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I went to change a leaking oil pan gasket today on my barracuda, when I got the pan off I did a inspection of everything and found #2 main cap was cracked in half! Ran great at the track 2 weeks ago and i drove it into the shop, has anyone ever seen this?
My question is can I take another cap off another block that I have, and have a machine shop take measurements off the old broken cap, and machine the new one to fit?
This 360 has been together for 10 years and has 200 plus passes on it and lots of street miles and i have never had a problem, I just don't want to build a new engine right now nor do I have the extra cash to do it.
Any help would be greatly appreciated!!
1968 Barracuda 360/727 11.20 @ 121 mph 421 rwhp
1985 Harley Sportster Bobber
2006 Ram 2500 sport - The Cudahlr
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Re: Broke A Main Cap!
[Re: Cudahlr]
#682078
04/27/10 08:51 PM
04/27/10 08:51 PM
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Joined: Nov 2003
Posts: 6,293
Rock Springs
Bob_Coomer
master
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master
Joined: Nov 2003
Posts: 6,293
Rock Springs
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Well you just might have saved the engine from certain catastrophic engine failure...but the good news stop there... The caps off another block will cause a bad misalignment and it wouldnt be pretty...If no other damage is there, consider your self very lucky. I would purchase a set of aftermarket main caps, have it lined bored would be the cheapest..and about the only means to save your current block.. 
[color:"red"]65 Hemi Belvedere coming soon [/color]
[color:"#00FF00"]557" Indy engine 1.07 60ft 144mph in the 8th 2100 lbs package [/color]
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Re: Broke A Main Cap!
[Re: snook]
#682080
04/27/10 09:09 PM
04/27/10 09:09 PM
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Joined: Aug 2009
Posts: 2,049
Mooresburg, Tn
'72CudaRacer
top fuel
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top fuel
Joined: Aug 2009
Posts: 2,049
Mooresburg, Tn
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Quote:
I'd try it. What have you got to lose? out
Block and crank on a GOOD day. Car (or worse) on a bad day when a rod gets spit out the side of the oil pan and puts oil on the track under the rear tires, thats all.
This is assuming that you don't lock up the engine when you torque the new main.
Brian
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Re: Broke A Main Cap!
[Re: Cudahlr]
#682082
04/27/10 09:17 PM
04/27/10 09:17 PM
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Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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Try using some plastagauge with the other cap and see what you come up with... it still wont tell you if its in line... but I would check the other cap... I've done some DUMB things before and got lucky
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Re: Broke A Main Cap!
[Re: camastomcat]
#682085
04/27/10 09:30 PM
04/27/10 09:30 PM
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Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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Quote:
IMO that's a recipie for disaster. The chances of another cap from another block working are a million to one. Don't do it. Pull it out and freshen it or take some time off. JMHO
I understand your opinion but I sure would look at
the other cap before I gave up.... it sure doesnt hurt
to look
As to why it broke.... unknown without looking at the
other caps(which I would do anyways)
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Re: Broke A Main Cap!
[Re: Cab_Burge]
#682087
04/27/10 09:38 PM
04/27/10 09:38 PM
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Joined: Nov 2009
Posts: 2,177
ill
dennismopar73
top fuel
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top fuel
Joined: Nov 2009
Posts: 2,177
ill
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yep take her down check everything replace with billet put a gurdle on it stud it!  
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Re: Broke A Main Cap!
[Re: Cudahlr]
#682088
04/27/10 09:45 PM
04/27/10 09:45 PM
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Joined: Feb 2008
Posts: 452
Monrovia, So-Cal, USA
racerhog
mopar
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mopar
Joined: Feb 2008
Posts: 452
Monrovia, So-Cal, USA
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More than likely, the main cap got a little stretch in one of the cap bolts and it allowed the crank to flex just enough to break it. Only rite way to fix it.... New caps and linebore.. 
Bob(Cowboy)Hogan
Monrovia So-Cal
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Re: Broke A Main Cap!
[Re: MR_P_BODY]
#682089
04/27/10 09:52 PM
04/27/10 09:52 PM
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Joined: Apr 2005
Posts: 2,128
Salt Lake City
camastomcat
top fuel
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top fuel
Joined: Apr 2005
Posts: 2,128
Salt Lake City
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Quote:
Quote:
IMO that's a recipie for disaster. The chances of another cap from another block working are a million to one. Don't do it. Pull it out and freshen it or take some time off. JMHO
I understand your opinion but I sure would look at
the other cap before I gave up.... it sure doesnt hurt
to look
As to why it broke.... unknown without looking at the
other caps(which I would do anyways)
Every time I have changed or replaced main caps, the block need to be aline honed. What do you think the chances are of "looking" at it and knowing whether it is square? And plasti-gauge?
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Re: Broke A Main Cap!
[Re: camastomcat]
#682091
04/27/10 09:59 PM
04/27/10 09:59 PM
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Joined: Dec 2008
Posts: 1,200
UK
602heavy
pro stock
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pro stock
Joined: Dec 2008
Posts: 1,200
UK
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Quote:
And plasti-gauge?
Why not?  , will tell you if it fits or not , could even stick some to the parting lines before torqueing her down.....................if it don't fit it don't fit.
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Re: Broke A Main Cap!
[Re: camastomcat]
#682094
04/27/10 10:28 PM
04/27/10 10:28 PM
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Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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Quote:
I guess what I would be thinking if it were mine is, if the main cap was broken, chances are that detonation caused it. And I think there is a good chance that with the kind of detonation causing that type of issue, the other caps have been stressed pretty hard too. When he takes the cap to the machine shop, they'll be able to tell him if they can fix it, but I would just pull the motor and go through it. It has lived a good life but needs to be looked at. And it's just my opinion, but that's the way I do things, right or wrong. It's a dangerous sport and there is no reason to take chances. Again JMO.
I agree, thats why I said to look at the other caps
to see if they are hurt OR if you can see any signs
of what the cause was.... he might want to have the
others magna checked to be sure they are ok.... I
myself would pull the engine down but I pull my
engine all the time(only takes me 45 minutes to have
the engine and trans sitting on the ground)
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Re: Broke A Main Cap!
[Re: MR_P_BODY]
#682095
04/28/10 12:02 AM
04/28/10 12:02 AM
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Joined: Nov 2003
Posts: 6,293
Rock Springs
Bob_Coomer
master
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master
Joined: Nov 2003
Posts: 6,293
Rock Springs
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I guess it wouldnt hurt to check... If you had a couple of blocks laying around and plenty of time...Remeber there is reason not to try any and all the other blocks caps..except the center...Unless you just wanted the number to be correct.. The chances are pretty slim imo that another cap will be close enough not to cause trouble....We re talking about the thickness of a piece of regular note book paper sliced in several layers here. Heck a human hair is about 2-3x's the the thickness of bearing clearance. Not only does the cap half to be centered, but the thickness in every angle must be perfect.
[color:"red"]65 Hemi Belvedere coming soon [/color]
[color:"#00FF00"]557" Indy engine 1.07 60ft 144mph in the 8th 2100 lbs package [/color]
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Re: Broke A Main Cap!
[Re: Bob_Coomer]
#682096
04/28/10 10:39 AM
04/28/10 10:39 AM
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Joined: Jan 2003
Posts: 21,076
Niles , Ohio
therocks
oh wait.but hey.lets see.oh yeah.
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oh wait.but hey.lets see.oh yeah.
Joined: Jan 2003
Posts: 21,076
Niles , Ohio
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Not a main but a rod cap in a 360 my brother had.It had a bad bearing.Pulled a rod cap from a 360 I had installed with new bearing.It ran for 4 years after that then he sold the van to a guy I knew and he put 4 years on it and it still ran.Sometimes you get lucky.Rocky
Chrysler Firepower
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