Re: 03 5.9 magnum heads
[Re: Sherwood Rogers]
#2391559
10/23/17 12:37 AM
10/23/17 12:37 AM
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Joined: Nov 2003
Posts: 36,040 Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
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Welcome aboard! All I can add is that the OE mags reportedly are commonly cracked inbetween the seats but that surprisingly they are still useable in alot of cases. I have my first OE set from a 5.2 & the spring pockets need to be opened up to 1.5" to use common springs but I am gonna dig into em with an open mind.
live every 24 hour block of time like it's your last day on earth
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Re: 03 5.9 magnum heads
[Re: Sherwood Rogers]
#2391635
10/23/17 08:37 AM
10/23/17 08:37 AM
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Joined: Jan 2003
Posts: 3,920 n.e. pa.
65rbdodge
master
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master
Joined: Jan 2003
Posts: 3,920
n.e. pa.
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Yes they crack but I haven’t heard of it causing any problems but I’m sure there are exceptions. I have junkyard magnum heads on my 318. I lapped the valves and noticed they were cracked but put them on my motor anyway. I have had no problems. If I were to replace them I would go with engine quest heads from hughes engines. They say the flow as much as eddy heads for less money.
Last edited by 65rbdodge; 10/23/17 08:41 AM.
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Re: 03 5.9 magnum heads
[Re: Sherwood Rogers]
#2391725
10/23/17 12:15 PM
10/23/17 12:15 PM
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Joined: Aug 2005
Posts: 5,993 Salem
Grizzly
Moparts Proctologist
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Moparts Proctologist
Joined: Aug 2005
Posts: 5,993
Salem
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I think it is the catalytic converters, 360view.
One of my Clients was telling me he cracked 2 heads on his 5.7 hemi. He told the dealership to cut the converters out and he said the problem was solved.
Mo' Farts
Moderated by "tbagger".
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Re: 03 5.9 magnum heads
[Re: Grizzly]
#2391732
10/23/17 12:28 PM
10/23/17 12:28 PM
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Joined: Nov 2003
Posts: 36,040 Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
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^^^ interesting! that sounds like it could be the source of that very common problem
live every 24 hour block of time like it's your last day on earth
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Re: 03 5.9 magnum heads
[Re: Sherwood Rogers]
#2391745
10/23/17 12:48 PM
10/23/17 12:48 PM
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Joined: Aug 2005
Posts: 5,993 Salem
Grizzly
Moparts Proctologist
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Moparts Proctologist
Joined: Aug 2005
Posts: 5,993
Salem
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I thought so too, Robert.
You think of all that heat getting built up between the exhaust port and that blob of mesh you can't even see a flashlight through in the converter, add a 195 thermostat to it.........crack.
I cut them out of everything, big difference.
Mo' Farts
Moderated by "tbagger".
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Re: 03 5.9 magnum heads
[Re: Sherwood Rogers]
#2392025
10/23/17 09:05 PM
10/23/17 09:05 PM
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Joined: May 2006
Posts: 1,260 New Mexico
Adobedude
pro stock
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pro stock
Joined: May 2006
Posts: 1,260
New Mexico
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Unless you're shooting for the best time slip, go for the Engine Quest Heads.
Just make sure you get anything you buy checked out, don't just bolt em on out of the box...Eddy Head valve guides are too tight, etc....
2001 Dodge Dakota 408 All Motor 11.27 @ 117.83 mph 2017 NM Mopar Challenge Series Champion.
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Re: 03 5.9 magnum heads
[Re: Sherwood Rogers]
#2392075
10/23/17 10:32 PM
10/23/17 10:32 PM
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Joined: Jan 2006
Posts: 8,162 USA
360view
Moparts resident spammer
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Moparts resident spammer
Joined: Jan 2006
Posts: 8,162
USA
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Sample quote Cast iron cylinder heads had machined top surfaces to provide smooth, uniform sealing surfaces for the cylinder head covers. For durability in heavy-duty service, the heads had high-nickel chromium exhaust valve seat inserts. End quote From https://www.allpar.com/mopar/V10.html
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Re: 03 5.9 magnum heads
[Re: Sherwood Rogers]
#2392940
10/25/17 03:52 PM
10/25/17 03:52 PM
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Joined: Jan 2005
Posts: 12,406 Kalispell Mt.
HotRodDave
I Live Here
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I Live Here
Joined: Jan 2005
Posts: 12,406
Kalispell Mt.
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It was the heat treat process itself that cracked the heads, I bought a brand new pair from mopar not re-man and they were cracked, I got my money back and have been running cracked magnum heads ever since.
The only un-cracked ones I found were on 5.2s, someone said they were actually made in a different factory so may have been treated a little better.
Some things may make them worse during use like
1. EGR slowing down the burn speed so the mix is still burning as the valve is opened instead of burning faster in the chamber where it should be before the valve opens.
2. Overheating because of many things common to these engine including thermostat housing leak, timing cover leak, radiator leak and water pump leak. Even so I have never seen coolant use as a result of cracked magnum heads, it always turns out to be something else.
3. Another possible difference in the 5.2 and 5.9 is the 5.2 has more cylinder pressure than a 5.9 because of a higher compresison ratio and a better cam profile, that makes the mix burn in the combustion chamber instead of on its way out the ex valve.
A better reason to me to run a head like an EQ with hard ex seat is because the factory heads get severly receded ex seats after 150,000 or so miles. I would run the EQ as a first choice in a truck over the eddy because it's iron and flows better. If it's a hot rod and not a truck then sure go with the eddy.
I probably went through 200 heads to find an uncracked pair on my last hot rod build, the only reason I bothered is because I was putting in bigger valves.
I am not causing global warming, I am just trying to hold off a impending Ice Age!
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Re: 03 5.9 magnum heads
[Re: HotRodDave]
#2393080
10/25/17 09:24 PM
10/25/17 09:24 PM
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Joined: Nov 2003
Posts: 36,040 Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
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Oh OK, maybe my 5.2 mags will turn out OK. Good info Dave, thank you!
live every 24 hour block of time like it's your last day on earth
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