Magnum Heads onto LA block

Bruceynz

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Hi Guys,

I thought I saw a sticky for this somewhere, a search didn't turn up anything, so if there is a post can someone point me in the right direction.

I am not happy with the performance of my 360 LA engine, it goes ok! But it should go better! I suffer from all the same problems, low comp, open chamber heads, poor flow. I have been exploring all kinds of options (5.7 hemi, 408 crate engine, alloy heads) but I think what I want to do is put magnum heads onto my LA block.

So I am going to need

Heads - What are good bang for buck magnum heads? (I see recondition ones on ebay for the $200 mark) does anyone have any good heads? Can anyone recommend any that might be a bit better than stock?

Push rods - What length can anyone recommend some? (I need some with holes up the middle)

Rockers, where do I get all the rocker gear I need?

Valve covers, should be able to find them on ebay, need low profile ones to clear my brake booster.

And I will need an intake, but thats not to bad to sort, edelbrock will have that covered.

Thanks
Bruce
 

brotherGood

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kkritsilas

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Bruceynz:

Start here:

magnumswap.com

For a good background on the Magnum/LA differences.

A lot of background material is in this article (based on the 318, but covers a lot that applies to the 360):

318 Engine Build - A Parts Book 400HP 318 - Mopar Muscle Magazine

Some ideas are here:

350-400hp budget build 360 ideas???

If you are going to d a full build up, I would skip the shaving of the decks, just go with the EngineQuest or Magnum heads, and the KB pistons and thin head gaskets that increase compression. Compression is nice, but it has to run on regular gas, which around here mean 89 octane. I know you will be giving up some horsepower, but I don't think it is worth chasing every last horse available if it means that you need to run mid grade or premium gas. If you have the money and do want it, go for it, but know what you are getting into.

Also, the Magnum heads have a known tendency to crack between the valves. Have any Magnum heads that you want to use thoroughly checked out. Part of the reason that the EngineQuest heads exist is because of this problem (they are also avallable with LA pattern intake maniforld bolts, so your current intake will bolt up).
 

Greg55_99

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I've heard the same about Magnum heads tendency to crack. Kinda puts a damper on boneyard parts.
 

kkritsilas

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The only real bad point of the Magnum head is the cracking. In almost all other ways, it is a really good factory head by any measure. Ma Mopar did a great job of correcting a lot of the flow restrictions in the LA heads, decreased the combustion chamber volume, and upped the valve size. Seems like they designed the area between the valves a little too thin.

I have seen one set of cracked Magnum heads. Had to look real close to see it (it had to be pointed out to me). Some are saying that some cracks are not fatal, but all Magnum heads need to be checked to find out if they are leaking coolant in my mind, just to avoid having to tear down an engine a second time. The EngineQuest heads are specifically designed to avoid this type of cracking. In addition, they actually flow better than the Magnum heads do. Not a night and day difference, but the improvement is there. With the other advantages brought by the EngineQuest heads (crack elimination, ability to order them with LA intake manifold bolt pattern), they are an option that should be considered seriously.
 

hemijoe

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stay away from magnum parts they are prone to cracing use an early set of 318 heads to get compression up to 11 to 1
 

brotherGood

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My magnum parts are fine...I can get another set that have been checked for cracks and are good to go for 150 right now. the exhaust seats are vulnerable, but that's usually related to overheating from what I've heard. once you find a good set, they're well worth it
 

bzzzz

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brotherGood

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Yeah, I can't remember where I sourced them though.

This reminds me, I need to quit dragging my feet and build my 5.9..but I don't have a car for it.
 

bzzzz

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Sorry for the long break ! I meant to ask you how good it run? I imagine pretty strong?
 

brotherGood

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If you're referring to the 318 with mag heads, ran (and still runs) great. The 5.9, I sold before ever doing anything with.

The 318 (and car) are currently up for sale because Dad has lost interest in the car, and I am busy with a 442. If I had room, I'd get it back because I'm fairly certain that 318 would smoke the 442 when it's done.
 

LSM360

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I don't know if the heads on the old MP Magnum 360/300hp crate engines were same heads you are referring to as prone to cracking, but I owned two of those engines and they had no issues for over 50k each. Smooth idling and torque monsters. Really a great build. I don't have the part number for the heads but those swirl port combustion chamber iron magnum heads, stock bore 360, stainless 1.925 intake, 1.625 exhaust valves, mopar .250/.264 dur .385"/.401" lift hyd roller cam and HD valve springs and dual plane M1 intake was a GREAT engine! I'd probably only change one thing and that's the intake; edelbrock air gap instead (yes it'll fit under hood - I have one on my Diplomat now) or Performer. You can use the cast aluminum Mopar Magnum valve covers if you want they will fit no problem with booster. In my Diplomat this combo with 3.21 sure grip year.....what a tire shredding sleeper! I'd love to have another of this engine!
 

kkritsilas

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The factory Magnum heads are prone to cracking between the intake and exhaust valves. Not all will crack, and the cracks are not necessarily fatal flaws. However, if you are going to the trouble of locating Magnum heads, then having them checked for cracks (and possibly repaired), consider getting the Engine Quest heads, which are NOT prone to cracking (the thickness of the Engine Quest heads is thicker in the area that contacts the block, and between the valves) and flow even better than the Magnum heads. They are also available in bolt patterns that will take either an LA type intake and a Magnum intake (one or the other).
 
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