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Re: Magnum heads on 360 LA
[Re: Mapandjlp]
#682177
04/27/10 11:19 PM
04/27/10 11:19 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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my unmilled mags were 63 cc's
live every 24 hour block of time like it's your last day on earth
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Re: Magnum heads on 360 LA
[Re: Kern Dog]
#682183
04/28/10 06:23 AM
04/28/10 06:23 AM
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Joined: Jun 2008
Posts: 10,847
Oakdale CT
gdonovan
I Live Here
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I Live Here
Joined: Jun 2008
Posts: 10,847
Oakdale CT
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Quote:
Regarding the "Large Paperweights" cracked heads....What caused you to remove them? Did you blow a head gasket or get leaks into the cooling system? I passed on several junkyard heads when I saw that they were cracked. My machinist said that in most cases, the cracks would pose no problem. I didn't want to risk it. 
As a retired Chrysler line tech I can't recall a single magnum 5.2 or 5.9 that was in the shop for a problem caused by cracked heads.
Intakes plates sucking oil yes, cracks in the head causing a problem no.
Like anything in life I'm sure it caused someone a problem but working on thousands of Dodge rams at Linder Dodge we never ran across it.
IMHO
Gary
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Re: Magnum heads on 360 LA
[Re: Mapandjlp]
#682184
04/28/10 07:00 AM
04/28/10 07:00 AM
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Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
patrick
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
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Quote:
I've been trying to figure out the best way to build the 360 for my Challenger. I'm considering magnum heads but have a couple of questions.
First - are the holes for mounting the PS pump, A/C, and Alternator bracketry the same as the LA heads?
Second - any thoughts on what effect they'll have on compression ratio on my '75 360 if I stick with the stock pistons?
Thanks, Guys! If anyone can help, I know you all can.
with stock pistons and if you can find the thin (.028") head gaskets, you'll be about 8.75:1 with magnum heads. the hughes ones for $699/pr is the best deal around, as they have springs that'll handle a nice hydraulic roller or solid flat tappet up to about .540" lift.
the accessory holes are in the same location as the LA heads, but they are all on the same plane, wheras the LA's lower hole is rearward by like 3/4" or 1". I had to modify my alternator bracket to fit. also, the front shape of the head is slightly different, and interfered with the back of the alternator, and I had to space all my accessories out about 1/8".
1976 Spinnaker White Plymouth Duster, /6 A833OD
1986 Silver/Twilight Blue Chrysler 5th Ave HotRod **SOLD!***
2011 Toxic Orange Dodge Charger R/T
2017 Grand Cherokee Overland
2014 Jeep Cherokee Latitude (holy crap, my daughter is driving)
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Re: Magnum heads on 360 LA
[Re: dmerc]
#682186
04/28/10 04:41 PM
04/28/10 04:41 PM
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Joined: Jan 2010
Posts: 509
Middle River, MD
Mapandjlp
OP
mopar
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OP
mopar
Joined: Jan 2010
Posts: 509
Middle River, MD
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Quote:
I used Magnum heads, Weisco dished pistons to get tight quench and a 4 inch crank. I'm very happy with the results 
Did you have to do any other work to the block to use the 4" crank? No clearancing? What rods did you use?
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Re: Magnum heads on 360 LA
[Re: Mapandjlp]
#682188
04/28/10 08:39 PM
04/28/10 08:39 PM
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Joined: Dec 2004
Posts: 1,061
New Mexico
dmerc
super stock
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super stock
Joined: Dec 2004
Posts: 1,061
New Mexico
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Quote:
Quote:
I used Magnum heads, Weisco dished pistons to get tight quench and a 4 inch crank. I'm very happy with the results
Did you have to do any other work to the block to use the 4" crank? No clearancing? What rods did you use?
Nope, no grinding on anything. I too used the SIR rods and as a bonus I was able to neutral balance the crank without using any mallory metal.
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Re: Magnum heads on 360 LA
[Re: Kern Dog]
#682191
04/29/10 12:58 AM
04/29/10 12:58 AM
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Joined: Mar 2007
Posts: 110
Concord California
Evil_Ways
member
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member
Joined: Mar 2007
Posts: 110
Concord California
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Quote:
Regarding the "Large Paperweights" cracked heads....What caused you to remove them? Did you blow a head gasket or get leaks into the cooling system? I passed on several junkyard heads when I saw that they were cracked. My machinist said that in most cases, the cracks would pose no problem. I didn't want to risk it.
Actually I never even installed them. I bought them from someone who had them on a freshly rebuilt motor (maybe 1500 - 2000 miles on them) and then decided to go with some edelbrocks and a bigger motor. After reading about so many people getting magnum heads and then finding out they were cracked. I took mine to my usual machine shop just for some piece of mind.
They called me back and said they were BOTH cracked right between the intake and exhaust valves. They said they see alot of the magnum heads come in and that's the spot they always crack. Something about a thin spot in the castings.
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Re: Magnum heads on 360 LA
[Re: RapidRobert]
#682192
04/30/10 06:26 AM
04/30/10 06:26 AM
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Joined: Dec 2004
Posts: 1,061
New Mexico
dmerc
super stock
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super stock
Joined: Dec 2004
Posts: 1,061
New Mexico
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Quote:
Quote:
Nope, no grinding on anything. I too used the SIR rods and as a bonus I was able to neutral balance the crank without using any mallory metal.
Which 4" crank and do you remember the bobweight?
Pretty sure it was an Eagle cast crank and the bob weight total was 1760 grams.
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Re: Magnum heads on 360 LA
[Re: dmerc]
#682193
04/30/10 09:44 AM
04/30/10 09:44 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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Quote:
Pretty sure it was an Eagle cast crank and the bob weight total was 1760 grams.
thank you Dmerc and I have an Eagle cast 4" crank.
Last edited by RapidRobert; 04/30/10 09:45 AM.
live every 24 hour block of time like it's your last day on earth
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Re: Magnum heads on 360 LA
[Re: HotRodDave]
#682196
05/01/10 08:39 PM
05/01/10 08:39 PM
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Joined: Dec 2004
Posts: 1,061
New Mexico
dmerc
super stock
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super stock
Joined: Dec 2004
Posts: 1,061
New Mexico
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Quote:
the eagle cast cranks balance very easily because they leave out critical weight in important places on the rod journal side of the crank, particularly the front journal overlap area, seen quite a few break in extremely mild engines 
I noticed this very thing when I had my machinist balanced my crank. He didn't seem concerned though... But they are scary thin in spots. Hope mine doesnt grenade soon So far so good though  I wonder what happens when a crank breaks like that. Maybe it's not as bad as a thrown rod 
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When I called them they said no problems they are aware of. I said thats funny the local rebuilder says most sets they see are all cracked between the valves. The truck now has about 86000 miles so far so good. The reman heads I put on were repaired in this same area.
. thanks Dave for the heads up I will keep it mild (sort of) 
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