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#2391481 - 10/22/17 08:23 PM 03 5.9 magnum heads
Sherwood Rogers Offline
member

Registered: 10/19/17
Posts: 1
Loc: South Carolina
Anyone replaced there factory heads with the Edelbrock heads? I’m thinking about it. Any suggestions or input on my idea? I could go back with factory but I’m worried that those will eventually rack between the valves like all the other Chrysler heads do. My set was cracked up real bad when I got the truck apparently the previous owner drove it after it ran not. So yeah I’m a little weary on oem heads . I found 2- used sets and those was cracked as well.

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#2391559 - 10/22/17 10:37 PM Re: 03 5.9 magnum heads [Re: Sherwood Rogers]
RapidRobert Offline
Circle Track

Registered: 11/20/03
Posts: 32703
Loc: Lincoln Nebraska
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.
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#2391635 - 10/23/17 06:37 AM Re: 03 5.9 magnum heads [Re: Sherwood Rogers]
65rbdodge Offline


Registered: 01/19/03
Posts: 3870
Loc: n.e. pa.
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.


Edited by 65rbdodge (10/23/17 06:41 AM)

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#2391653 - 10/23/17 08:13 AM Re: 03 5.9 magnum heads [Re: Sherwood Rogers]
360view Offline
master

Registered: 01/18/06
Posts: 4123
Loc: USA
Is there any evidence that 1992-1995 Magnum heads do not crack,
but 1996-2003 Magnum heads do?

EGR keeps peak exhaust temperatures lower. On the 1992-1995 EGR turns on at 60% and off near full throttle. I am wondering if this reduced cracking?

Lots of Dodge Ram OEM catalytic converters developed high backpressure. I wonder if this promoted cracking?

I wonder what Chrysler engineers knew when they designed the very similar 8L V10 cylinder heads around year 1991 with knowledge that these would see a lot of towing duty at higher sustained loads. My fuzzy memory is that they have different exhaust valve seat design with inserts?

There has been discussion here on Moparts of later year non Magnum cylinder head hardened inserts falling out, so Chrysler had design troubles there too.

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#2391725 - 10/23/17 10:15 AM Re: 03 5.9 magnum heads [Re: Sherwood Rogers]
Grizzly Offline
master

Registered: 08/24/05
Posts: 4654
Loc: at work
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.

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#2391732 - 10/23/17 10:28 AM Re: 03 5.9 magnum heads [Re: Grizzly]
RapidRobert Offline
Circle Track

Registered: 11/20/03
Posts: 32703
Loc: Lincoln Nebraska
^^^ interesting! that sounds like it could be the source of that very common problem
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#2391745 - 10/23/17 10:48 AM Re: 03 5.9 magnum heads [Re: Sherwood Rogers]
Grizzly Offline
master

Registered: 08/24/05
Posts: 4654
Loc: at work
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.

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#2391977 - 10/23/17 04:57 PM Re: 03 5.9 magnum heads [Re: 360view]
dogdays Offline
I Live Here

Registered: 01/20/03
Posts: 15791
Well no passenger car Mopar engine since the early '60s had valve seat inserts in a cast iron head. I doubt that the V10 Ram truck had them either.

Over the years there has been no particular year or years of the Mag heads that were more prone to cracking, and no difference between US and Mexican Mag heads in that respect, either.

To the OP: If you can afford to use a set of Edelbrock Mag heads, go for it. As far as I am concerned, there is no downside to this unless it makes you have to eat ramen.

The Enginequest iron heads are in the middle as far as performance and price.

Get real world prices for the three options before you jump.

R.

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#2392025 - 10/23/17 07:05 PM Re: 03 5.9 magnum heads [Re: Sherwood Rogers]
Adobedude Offline
super stock

Registered: 05/07/06
Posts: 1144
Loc: New Mexico
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....
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#2392040 - 10/23/17 07:30 PM Re: 03 5.9 magnum heads [Re: Sherwood Rogers]
EV2Bird Offline
On Vacation

Registered: 06/23/14
Posts: 2816
Loc: Kansas Roads Between 0 and 140...
Well no passenger car Mopar engine since the early '60s had valve seat inserts in a cast iron head.

Hugh?

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#2392075 - 10/23/17 08:32 PM Re: 03 5.9 magnum heads [Re: Sherwood Rogers]
360view Offline
master

Registered: 01/18/06
Posts: 4123
Loc: USA
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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#2392940 - 10/25/17 01:52 PM Re: 03 5.9 magnum heads [Re: Sherwood Rogers]
HotRodDave Offline
master

Registered: 01/29/05
Posts: 9447
Loc: Kalispell Mt.
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.
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68 cuda 360 notchback SOLD

1996 Ram 2500 5.9 eddy intake EQ heads, mild cam upgrade great tow rig!


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#2393080 - 10/25/17 07:24 PM Re: 03 5.9 magnum heads [Re: HotRodDave]
RapidRobert Offline
Circle Track

Registered: 11/20/03
Posts: 32703
Loc: Lincoln Nebraska
Oh OK, maybe my 5.2 mags will turn out OK. Good info Dave, thank you!
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